Medical News

Updated at 3:38 p.m. ET on May 31, 2025

Solving HIV vaccination—a puzzle that scientists have been tackling for decades without success—could be like cracking the code to a safe. The key, they now think, may be delivering a series of different shots in a specific sequence, iteratively training the body to produce a strong, broad immune response that will endure against the fast-mutating virus, ideally for a lifetime.

Figuring out which ingredients to include in those shots, and in which order, is one of the trickiest immunological conundrums that researchers have ever faced. But mRNA, the fast, flexible technology that delivered two of the world’s first COVID-19 vaccines in record time, is ideal for that kind of brute-force tinkering, and may be the most important tool for getting an effective HIV vaccine, Julie McElrath, the head of the Vaccine and Infectious Disease Division at Fred Hutchinson Cancer Center, in Seattle, told me. Multiple mRNA-based HIV vaccines are now in clinical trials, and early data suggest that they’re prompting the type of immune responses that researchers think are essential to keeping HIV at bay—and that other vaccine candidates have struggled to elicit at all.

But recently, several promising mRNA HIV-vaccine candidates have slammed up against a technical roadblock. In two small clinical trials, 7 to 18 percent of participants developed rashes and other skin reactions after getting the shots—including multiple cases of chronic hives that troubled volunteers for months after they were immunized. All of the vaccines were manufactured by Moderna.

The rashes aren’t life-threatening; they’re also readily treatable. Still, they can be debilitating and distressing. “I’ve had patients who literally can’t go to work,” Kimberly Blumenthal, an allergist and immunologist at Massachusetts General Hospital, who has treated people with chronic hives, told me. The rate at which they’re occurring in the trials is also out of the norm, and no one has an explanation yet for the root cause. To prioritize patient safety, mRNA HIV-vaccine research in people has slowed as researchers try to suss out the cause of the hives, William Schief, the Scripps Research Institute biophysicist who helped design the vaccines, told me. (Schief also holds titles at Moderna and at IAVI, the nonprofit that sponsored some of the HIV-vaccine work.)

At any time, a side effect this uncomfortable and prolonged would give researchers pause. But in 2025, a setback for a high-profile mRNA vaccine trial—focused on HIV, no less—could more fundamentally upend potentially lifesaving research.

Secretary of Health and Human Services Robert F. Kennedy Jr., a longtime and prominent anti-vaccine activist, has repeatedly questioned the safety of mRNA COVID vaccines. He and agency leaders are already recommending that fewer Americans take vaccines and creating new hurdles to vaccine approval. Since January, the National Institutes of Health, under HHS’s direction, has also terminated funding for hundreds of research projects related to HIV and vaccines. This week, the department canceled Moderna’s nearly $600 million contract to develop mRNA-based flu vaccines.

The HIV-vaccine studies that detected the skin reactions were also supported by NIH funding, and the researchers involved collaborated directly with NIH scientists. But those partnerships have since been terminated, and the NIH is now telling several agency-supported researchers working on HIV vaccines that the government is not planning to continue funding their work, according to several researchers I talked with.

When reached for comment, Emily Hilliard, HHS’s press secretary, wrote in an email, “The reality is that mRNA technology remains under-tested, and we are not going to spend taxpayer dollars repeating the mistakes of the last administration, which concealed legitimate safety concerns from the public”—referencing the mRNA-based COVID-19 vaccines, which were rigorously tested in clinical trials, and billions of doses of which have been safely administered people around the world.

Under normal circumstances, detecting rashes in a small vaccine-safety study would represent a routine scientific setback, and prove that the trials served their intended purpose. But the administration’s anti-vaccine stances have created a culture of fear among scientists: Several of the researchers I contacted for this story declined to comment, for fear of publicly tying their name or institution to reporting on mRNA vaccines and losing funding for their research. Science requires resources and open discussion—in torpedoing both, the Trump administration is rapidly undoing decades of progress toward ending the HIV pandemic.

Researchers running the mRNA HIV-vaccine trials first took note of the rashes in 2022, shortly after studies began. But as they started to publicly discuss the side effect, and media reports of them began to emerge, many scientists in the field weren’t quite sure what to make of the initial findings. The trial in which it had been reported had enrolled only 60 people, and it wasn’t set up to rigorously look at a mysterious side effect. “The sort of feeling was, Yeah, that’s a bit weird, God knows what happened,” John Moore, an HIV researcher and vaccinologist at Cornell, told me. This April and May, though, researchers independently published two papers describing the rashes, for four separate vaccines, in two separate trials: one for the IAVI-backed vaccine and another run by the HIV Vaccine Trials Network. Now, the side effect is “real, confirmed, generalizable,” Moore said. “And we don’t know why it’s happening.”

The vaccines in question target slightly different parts of the virus. But all of them rely on a Moderna-manufactured mRNA backbone, and all of them triggered, in up to about 10 percent of participants, chronic hives that emerged a few days or weeks after vaccination and in many cases lasted for months. That’s a long time to be battling itching and discomfort—and it threatens to be a major deterrent to completing the series of vaccines, or potentially starting at all, Genevieve Fouda, an immunologist and HIV researcher at Cornell, told me.

Delayed, chronic hives have long been known as a rare side effect of vaccines, including mRNA-based COVID vaccines. But the rates are generally very low—usually well under 1 percent, and often detectable only in massive studies of thousands of people. To see these rashes crop up in two small safety studies—one of 60 people, the other of 108—is a significant departure from precedent, scientists told me. And working out why they’re appearing at such high rates will take time. Although researchers understand that the reactions are a kind of autoimmunity—in which the body inadvertently learns to attack itself—they don’t know exactly why rashes occur after certain immunizations or infections, Blumenthal told me.

In this case, the data so far do point to the specific combination of mRNA and HIV as a root cause. Other mRNA vaccines, including Moderna’s, haven’t had this issue to anywhere near this degree; neither have other HIV vaccines that have made it into people. And several researchers pointed out to me that, so far, the only trials that they’re aware of in which these hives have turned up at this frequency have involved a Moderna-manufactured product. None of the other vaccines being tested by the HIV Vaccine Trials Network, for instance, has seen rashes at that rate—including other, non-Moderna mRNA HIV vaccines, Jim Kublin, the director of HVTN, told me. (Barton Haynes, the Duke immunologist leading work on one of the non-Moderna vaccines, told me he and his colleagues have not encountered the same skin-reaction problem.) Hives also appear to have been a more common side effect of the Moderna COVID vaccines than of the Pfizer ones, though still overall rare. “This is truly an outlier in terms of what we’ve seen,” Robert Paris, a vice president at Moderna, told me.

A persistent mRNA problem would be a major blow to HIV-vaccine development. When the technology emerged, it sped progress like nothing else: “Things that originally took us about three years, we could do them in maybe three and a half months or so,” Mark Feinberg, the head of IAVI, told me. The early results for these vaccines have also been very promising, and before the hives were detected, researchers were well on their way to testing even more iterations of mRNA-based HIV vaccines, to crack the final immunization code. But for the moment, “there’s no appetite to say, ‘Let’s try all these different immunogens and see what happens,’” Schief, the Scripps researcher who helped design the vaccines, told me.

Still, most of the researchers I spoke with insisted that they’ll find a solution soon. The mRNA vaccines for HIV “are not at all dead in the water,” Kublin told me. If needed, scientists could tweak the vaccine recipe, or combine the mRNA approach with another technology. The fix may be as simple as lowering the vaccine dose, a strategy that Schief and Feinberg are working to test in a new trial based in South Africa. (Moderna’s COVID vaccine also contained more than three times as much mRNA as Pfizer’s—and one study found that lowering the Moderna dose seemed to reduce the rate of certain skin reactions.)

Successful HIV vaccination may require a balancing act—minimizing hives, while still delivering enough mRNA to rile up the immune system. But researchers may not be able to drive the rates of skin reactions down to zero: HIV is especially adept at cloaking itself from the immune system, and there may be few ways to force the body to attack the virus without producing collateral damage. And Schief and others couldn’t say what rate of hives would be acceptably low. The virus is so infectious and deadly that some minor side effects may be worth the risk, if the vaccine is effective at generating the right immune response. But even a perfect, immunity-inducing shot won’t do the world any good if people are afraid to take it.

Still, if a rash can dissuade someone from vaccination, so, too, can misinformation, or an official’s decision to stop recommending a shot. No vaccine progress will be made if the federal government doesn’t want it to happen: Paris, of Moderna, told me that earlier this spring, the NIH terminated its partnership with the researchers developing these mRNA HIV vaccines, forcing the scientists to seek alternate sources of support. And yesterday, Schief and Haynes were told that their groups at Scripps and Duke would not have the opportunity to renew funding for the two HIV-vaccine-focused research consortia that their institutions lead—millions of dollars that the researchers had been told to expect they would receive, and that have been powering the development of their mRNA shots. The rationale, Haynes told me, as it was described to him, was “due to the desire to go with currently available approaches to eliminate HIV.” Currently available approaches include community education and preventive drugs, but notably, no vaccine. (HHS did not respond to questions about these funding shifts.)

“Unless we can find a substitute source of support, this work won’t go forward,” Haynes told me. If the project of HIV vaccination looks less promising right now than it has in years, that’s not about science or technology, or about any single side effect: It’s about politics.

In contrast to his aging predecessor, President Trump appears robust and energetic. Yet, like Joe Biden, Donald Trump is an elderly man, and he will become the oldest sitting president in U.S. history by the end of his second term. In light of recent revelations about Biden’s declining health, as a doctor and an expert in aging, I have been thinking about the responsibilities of Trump’s doctors to him and to the American public. If the way we care for elderly people is distinct because their bodies and risks are distinct, perhaps the care of an elderly president should be, too.

Presidents are getting older—which is to be expected, given the doubling of the average human lifespan across the 20th century. As we age, the likelihood of disease goes up significantly each decade (which makes sense because human mortality is holding steady at 100 percent). An elevated risk of disease shouldn’t exclude a person from any job—even one as important as the U.S. presidency—but in elderhood, certain diseases become more prevalent, such as heart disease and cancer, the leading causes of death for adults. After age 70, a person is also at increased risk for one or more health conditions in a category unique to old age, the so-called geriatric syndromes, which include cognitive impairment, functional decline, falls, and frailty.

On the surface, Trump seems stronger and less vulnerable than Biden did. Yet looks do not necessarily reflect risk for illness and disability. A hallmark of advanced age is its variability: One person may be physically powerful but have dementia; another might have hearing loss but no cognitive changes; a third could have heart disease, diabetes, high blood pressure, and high cholesterol—physiologic time bombs that increase a person’s risk of major events such as heart attacks, strokes, and death.

And Donald Trump has lived in a way that raises his risk for heart and other serious diseases as he ages. For years, he has been overweight or obese, as measured by his BMI—which doesn’t distinguish between lean, muscular weight, and fat, meaning he is likely even less healthy than his abnormal BMI suggests. His gait, though better than Biden’s, demonstrates the same weakness of many lower extremity muscle groups, and his history of eschewing formal, particularly muscle-building, exercise means that his risk for falls and frailty is increasing more quickly than they would with resistance and balance training—recent signs that he might be adopting healthier habits notwithstanding. Equally important, fat on a body indicates fat in and around the body’s critical organs and blood vessels, including the brain and heart.

To truly understand our current president’s health, as a doctor I would want to know and follow not just his BMI but also his percentages of fat and muscle, and to track his strength, hand grip, and walking speed. His doctors should be discussing those predictive measures with him, as well as the negative effects his lifestyle might have on his heart health and cancer risk.

That would be true for any older patient, but the president’s crucial role may well change which additional tests his doctors should consider. For example, routine screening for prostate cancer—which Biden reportedly did not undergo—is not recommended for men over age 70 because most, even if they develop prostate cancer, will die of something else. But these tests might make sense for a president over age 70 because the risks of a serious form of the cancer would affect not just the man but the country and the wider world. Other tests that fall into this category might include functional heart and brain scans, additional cancer screenings beyond usual age cutoffs, and certain biomarkers.

More aggressive screening would still have trade-offs for both the president and the nation. It could subject the president to unnecessary procedures and psychological stress. Opponents might use even a clinically insignificant diagnosis to their advantage. But more aggressive screening might also enable earlier diagnosis or, if a potentially disabling or lethal condition is found, succession planning.

Because the risk of adverse health events increases throughout the last third of life, we geriatricians recommend discussing what’s known as “goals of care” with each patient—to get a sense of their values and their fears. We ask about what matters most to them in their life, which situations seem worth some suffering and which do not, and how they have handled and experienced past health events. Programs proven to help people clarify their priorities and plan ahead can help patients, families, and doctors choose a course most consistent with their values and goals.

For a president, such conversations are even more essential. First, they could help the president, as an individual, think through how to separate political pressures from personal needs and family responsibilities. Second, having a plan that protects the country should be a core responsibility for anyone in high office, and an elderly president in particular should think ahead of time about how to best serve the United States in the event of a majorly debilitating health event or general decline.

Goals-of-care conversations are difficult for some people—and some doctors. If Trump’s doctors are not skilled at this sort of conversation, they should engage a consultant who is able to push him to reflect on how his answers to these questions would affect his ability to do his job, or the functioning of the country. Just as it’s the president’s responsibility to answer these difficult questions, so too is it his doctors’ responsibility to pose them.

When asked to comment, the White House did not address questions about Trump’s risk, mitigation strategies, or contingency planning, but Liz Huston, a spokesperson, said over email that Trump “receives the highest-quality medical care” from his doctors and “is in great health as evidenced by the results of his comprehensive annual physical exam.” (Huston also said the White House was not going to accept the unsolicited advice of “an activist Democrat doctor,” referencing a 2023 article on aging politicians in which I wrote, based on what reporters had told me, that journalists decades younger than Nancy Pelosi had trouble keeping up with her.)

Trump’s physicians face another challenge that most clinicians do not: Which information about their patient’s health should they share with the public? In both Trump terms, many physicians have struggled to believe the information provided by the president’s medical team and have suspected that his risks are being substantially downplayed. And now we know the problem exists in both major political parties. Biden’s team seemingly withheld information that would have made clear that he did not have the physical or cognitive ability to govern for a second term. Surely, with such high stakes, the president’s health is an exception to the usual rules of patient privacy. When a person signs up for “public office,” by definition they forfeit some of the privacy protections the rest of us are entitled to by law. Their health and ability to do their job affect hundreds of millions of lives.

The U.S. could consider imposing a maximum age limit on the presidency. But that one-size-fits-all approach risks eliminating potentially fit and favored candidates. In its absence, the person leading the country should receive station-specific, evidence-based, and person-centered care—that attends to their role, medical conditions, functional abilities, and preferences. And the American public deserves transparency about the president’s health.

In contrast to his aging predecessor, President Trump appears robust and energetic. Yet, like Joe Biden, Donald Trump is an elderly man, and he will become the oldest sitting president in U.S. history by the end of his second term. In light of recent revelations about Biden’s declining health, as a doctor and an expert in aging, I have been thinking about the responsibilities of Trump’s doctors to him and to the American public. If the way we care for elderly people is distinct because their bodies and risks are distinct, perhaps the care of an elderly president should be, too.

Presidents are getting older—which is to be expected, given the doubling of the average human lifespan across the 20th century. As we age, the likelihood of disease goes up significantly each decade (which makes sense because human mortality is holding steady at 100 percent). An elevated risk of disease shouldn’t exclude a person from any job—even one as important as the U.S. presidency—but in elderhood, certain diseases become more prevalent, such as heart disease and cancer, the leading causes of death for adults. After age 70, a person is also at increased risk for one or more health conditions in a category unique to old age, the so-called geriatric syndromes, which include cognitive impairment, functional decline, falls, and frailty.

On the surface, Trump seems stronger and less vulnerable than Biden did. Yet looks do not necessarily reflect risk for illness and disability. A hallmark of advanced age is its variability: One person may be physically powerful but have dementia; another might have hearing loss but no cognitive changes; a third could have heart disease, diabetes, high blood pressure, and high cholesterol—physiologic time bombs that increase a person’s risk of major events such as heart attacks, strokes, and death.

And Donald Trump has lived in a way that raises his risk for heart and other serious diseases as he ages. For years, he has been overweight or obese, as measured by his BMI—which doesn’t distinguish between lean, muscular weight, and fat, meaning he is likely even less healthy than his abnormal BMI suggests. His gait, though better than Biden’s, demonstrates the same weakness of many lower extremity muscle groups, and his history of eschewing formal, particularly muscle-building, exercise means that his risk for falls and frailty is increasing more quickly than they would with resistance and balance training—recent signs that he might be adopting healthier habits notwithstanding. Equally important, fat on a body indicates fat in and around the body’s critical organs and blood vessels, including the brain and heart.

To truly understand our current president’s health, as a doctor I would want to know and follow not just his BMI but also his percentages of fat and muscle, and to track his strength, hand grip, and walking speed. His doctors should be discussing those predictive measures with him, as well as the negative effects his lifestyle might have on his heart health and cancer risk.

That would be true for any older patient, but the president’s crucial role may well change which additional tests his doctors should consider. For example, routine screening for prostate cancer—which Biden reportedly did not undergo—is not recommended for men over age 70 because most, even if they develop prostate cancer, will die of something else. But these tests might make sense for a president over age 70 because the risks of a serious form of the cancer would affect not just the man but the country and the wider world. Other tests that fall into this category might include functional heart and brain scans, additional cancer screenings beyond usual age cutoffs, and certain biomarkers.

More aggressive screening would still have trade-offs for both the president and the nation. It could subject the president to unnecessary procedures and psychological stress. Opponents might use even a clinically insignificant diagnosis to their advantage. But more aggressive screening might also enable earlier diagnosis or, if a potentially disabling or lethal condition is found, succession planning.

Because the risk of adverse health events increases throughout the last third of life, we geriatricians recommend discussing what’s known as “goals of care” with each patient—to get a sense of their values and their fears. We ask about what matters most to them in their life, which situations seem worth some suffering and which do not, and how they have handled and experienced past health events. Programs proven to help people clarify their priorities and plan ahead can help patients, families, and doctors choose a course most consistent with their values and goals.

For a president, such conversations are even more essential. First, they could help the president, as an individual, think through how to separate political pressures from personal needs and family responsibilities. Second, having a plan that protects the country should be a core responsibility for anyone in high office, and an elderly president in particular should think ahead of time about how to best serve the United States in the event of a majorly debilitating health event or general decline.

Goals-of-care conversations are difficult for some people—and some doctors. If Trump’s doctors are not skilled at this sort of conversation, they should engage a consultant who is able to push him to reflect on how his answers to these questions would affect his ability to do his job, or the functioning of the country. Just as it’s the president’s responsibility to answer these difficult questions, so too is it his doctors’ responsibility to pose them.

When asked to comment, the White House did not address questions about Trump’s risk, mitigation strategies, or contingency planning, but Liz Huston, a spokesperson, said over email that Trump “receives the highest-quality medical care” from his doctors and “is in great health as evidenced by the results of his comprehensive annual physical exam.” (Huston also said the White House was not going to accept the unsolicited advice of “an activist Democrat doctor,” referencing a 2023 article on aging politicians in which I wrote, based on what reporters had told me, that journalists decades younger than Nancy Pelosi had trouble keeping up with her.)

Trump’s physicians face another challenge that most clinicians do not: Which information about their patient’s health should they share with the public? In both Trump terms, many physicians have struggled to believe the information provided by the president’s medical team and have suspected that his risks are being substantially downplayed. And now we know the problem exists in both major political parties. Biden’s team seemingly withheld information that would have made clear that he did not have the physical or cognitive ability to govern for a second term. Surely, with such high stakes, the president’s health is an exception to the usual rules of patient privacy. When a person signs up for “public office,” by definition they forfeit some of the privacy protections the rest of us are entitled to by law. Their health and ability to do their job affect hundreds of millions of lives.

The U.S. could consider imposing a maximum age limit on the presidency. But that one-size-fits-all approach risks eliminating potentially fit and favored candidates. In its absence, the person leading the country should receive station-specific, evidence-based, and person-centered care—that attends to their role, medical conditions, functional abilities, and preferences. And the American public deserves transparency about the president’s health.

In contrast to his aging predecessor, President Trump appears robust and energetic. Yet, like Joe Biden, Donald Trump is an elderly man, and he will become the oldest sitting president in U.S. history by the end of his second term. In light of recent revelations about Biden’s declining health, as a doctor and an expert in aging, I have been thinking about the responsibilities of Trump’s doctors to him and to the American public. If the way we care for elderly people is distinct because their bodies and risks are distinct, perhaps the care of an elderly president should be, too.

Presidents are getting older—which is to be expected, given the doubling of the average human lifespan across the 20th century. As we age, the likelihood of disease goes up significantly each decade (which makes sense because human mortality is holding steady at 100 percent). An elevated risk of disease shouldn’t exclude a person from any job—even one as important as the U.S. presidency—but in elderhood, certain diseases become more prevalent, such as heart disease and cancer, the leading causes of death for adults. After age 70, a person is also at increased risk for one or more health conditions in a category unique to old age, the so-called geriatric syndromes, which include cognitive impairment, functional decline, falls, and frailty.

On the surface, Trump seems stronger and less vulnerable than Biden did. Yet looks do not necessarily reflect risk for illness and disability. A hallmark of advanced age is its variability: One person may be physically powerful but have dementia; another might have hearing loss but no cognitive changes; a third could have heart disease, diabetes, high blood pressure, and high cholesterol—physiologic time bombs that increase a person’s risk of major events such as heart attacks, strokes, and death.

And Donald Trump has lived in a way that raises his risk for heart and other serious diseases as he ages. For years, he has been overweight or obese, as measured by his BMI—which doesn’t distinguish between lean, muscular weight, and fat, meaning he is likely even less healthy than his abnormal BMI suggests. His gait, though better than Biden’s, demonstrates the same weakness of many lower extremity muscle groups, and his history of eschewing formal, particularly muscle-building, exercise means that his risk for falls and frailty is increasing more quickly than they would with resistance and balance training—recent signs that he might be adopting healthier habits notwithstanding. Equally important, fat on a body indicates fat in and around the body’s critical organs and blood vessels, including the brain and heart.

To truly understand our current president’s health, as a doctor I would want to know and follow not just his BMI but also his percentages of fat and muscle, and to track his strength, hand grip, and walking speed. His doctors should be discussing those predictive measures with him, as well as the negative effects his lifestyle might have on his heart health and cancer risk.

That would be true for any older patient, but the president’s crucial role may well change which additional tests his doctors should consider. For example, routine screening for prostate cancer—which Biden reportedly did not undergo—is not recommended for men over age 70 because most, even if they develop prostate cancer, will die of something else. But these tests might make sense for a president over age 70 because the risks of a serious form of the cancer would affect not just the man but the country and the wider world. Other tests that fall into this category might include functional heart and brain scans, additional cancer screenings beyond usual age cutoffs, and certain biomarkers.

More aggressive screening would still have trade-offs for both the president and the nation. It could subject the president to unnecessary procedures and psychological stress. Opponents might use even a clinically insignificant diagnosis to their advantage. But more aggressive screening might also enable earlier diagnosis or, if a potentially disabling or lethal condition is found, succession planning.

Because the risk of adverse health events increases throughout the last third of life, we geriatricians recommend discussing what’s known as “goals of care” with each patient—to get a sense of their values and their fears. We ask about what matters most to them in their life, which situations seem worth some suffering and which do not, and how they have handled and experienced past health events. Programs proven to help people clarify their priorities and plan ahead can help patients, families, and doctors choose a course most consistent with their values and goals.

For a president, such conversations are even more essential. First, they could help the president, as an individual, think through how to separate political pressures from personal needs and family responsibilities. Second, having a plan that protects the country should be a core responsibility for anyone in high office, and an elderly president in particular should think ahead of time about how to best serve the United States in the event of a majorly debilitating health event or general decline.

Goals-of-care conversations are difficult for some people—and some doctors. If Trump’s doctors are not skilled at this sort of conversation, they should engage a consultant who is able to push him to reflect on how his answers to these questions would affect his ability to do his job, or the functioning of the country. Just as it’s the president’s responsibility to answer these difficult questions, so too is it his doctors’ responsibility to pose them.

When asked to comment, the White House did not address questions about Trump’s risk, mitigation strategies, or contingency planning, but Liz Huston, a spokesperson, said over email that Trump “receives the highest-quality medical care” from his doctors and “is in great health as evidenced by the results of his comprehensive annual physical exam.” (Huston also said the White House was not going to accept the unsolicited advice of “an activist Democrat doctor,” referencing a 2023 article on aging politicians in which I wrote, based on what reporters had told me, that journalists decades younger than Nancy Pelosi had trouble keeping up with her.)

Trump’s physicians face another challenge that most clinicians do not: Which information about their patient’s health should they share with the public? In both Trump terms, many physicians have struggled to believe the information provided by the president’s medical team and have suspected that his risks are being substantially downplayed. And now we know the problem exists in both major political parties. Biden’s team seemingly withheld information that would have made clear that he did not have the physical or cognitive ability to govern for a second term. Surely, with such high stakes, the president’s health is an exception to the usual rules of patient privacy. When a person signs up for “public office,” by definition they forfeit some of the privacy protections the rest of us are entitled to by law. Their health and ability to do their job affect hundreds of millions of lives.

The U.S. could consider imposing a maximum age limit on the presidency. But that one-size-fits-all approach risks eliminating potentially fit and favored candidates. In its absence, the person leading the country should receive station-specific, evidence-based, and person-centered care—that attends to their role, medical conditions, functional abilities, and preferences. And the American public deserves transparency about the president’s health.

The United States has, for 70 years, been fighting a continuous aerial war against the New World screwworm, a parasite that eats animals alive: cow, pig, deer, dog, even human. (Its scientific name, C. hominivorax, translates to “man-eater.”) Larvae of the parasitic fly chew through flesh, transforming small nicks into big, gruesome wounds. But in the 1950s, the U.S. Department of Agriculture laid the groundwork for a continent-wide assault. Workers raised screwworms in factories, blasted them with radiation until they were sterile, and dropped the sterile adult screwworms by the millions—even hundreds of millions—weekly over the U.S., then farther south in Mexico, and eventually in the rest of North America.

The sterile flies proceeded to, well, screw the continent’s wild populations into oblivion, and in 2006, an invisible barrier was established at the Darién Gap, the jungle that straddles the Panama-Colombia border, to cordon the screwworm-free north off from the south. The barrier, as I observed when I reported from Panama several years ago, consisted of planes releasing millions of sterile screwworms to rain down over the Darién Gap every week. This never-ending battle kept the threat of screwworms far from America.

But in 2022, the barrier was breached. Cases in Panama—mostly in cattle—skyrocketed from dozens a year to 1,000, despite ongoing drops of sterile flies. The parasite then began moving northward, at first slowly and then rapidly by 2024, which is when I began getting alarmed emails from those following the situation in Central America. As of this month, the parasite has advanced 1,600 miles through eight countries to reach Oaxaca and Veracruz in Mexico, with 700 miles left to go until the Texas border. The U.S. subsequently suspended live-cattle imports from Mexico.

After this latest news broke, I spoke with Wayne Cockrell, a Texas rancher who fears the screwworm’s return to Texas is now a matter of when, not if. The anti-screwworm program cannot produce enough sterile flies to stop the parasite’s advance, much less beat it back down to Panama, Cockrell explained. He has followed the outbreak closely as the chair of the cattle-health committee for the Texas and Southwestern Cattle Raisers Association, even visiting the sterile-fly factory recently. “There’s a sense of dread on my part now,” he told me.

At 60, he is too young to remember screwworms himself, but he’s heard the horror stories. Every cut, every scratch, every navel of a newborn calf threatened to turn fatal in the pre-eradication era. If the parasite does take hold in the U.S. again, it could take decades to push screwworms back down to Panama. That is, after all, how long it took the first time. Decades of screwworm vigilance have been undone in just two years.

You only have to glance at a map to understand why the screwworm outbreak is now at an alarming inflection point.

Central America is shaped like a funnel with a long, bumpy tail that reaches its skinniest point in Panama. Back in the day, the USDA helped pay for screwworm eradication down to Panama out of not pure altruism but economic pragmatism: Establishing a 100-mile screwworm barrier there is cheaper than creating one at the 2,000-mile U.S.-Mexico border. Even after screwworms began creeping up the tail of the funnel recently, the anti-screwworm campaign had one last good chance of stopping them at a narrow isthmus in southern Mexico—after which the funnel grows dramatically wider. It failed. The latest screwworm detections in Oaxaca and Veracruz are just beyond the isthmus.

The wider the new front of the screwworm war grows, the more sterile screwworms are needed to stop the parasite’s advance. But the supply is already overstretched. The fly factory in Panama has increased production from its usual 20 million flies a week to its maximum of 100 million, which are now all being dispersed over Mexico. But planes used to drop 150 million flies a week over the isthmus in Mexico during the first eradication campaign in the 1980s. And when the front was even farther north in Mexico, a factory there churned out as many as 550 million flies weekly to cover the huge area. That factory, as well as one in Texas, has long since shut down.

The Texas and Southwestern Cattle Raisers Association is asking the USDA to build a new sterile-fly plant in the U.S., one big enough to produce the hundreds of millions that may soon be necessary. “We are working closely with Mexico to reestablish a biological barrier and prevent further geographic spread,” a USDA spokesperson wrote in response to questions about the adequacy of sterile-fly production. “If the fly spreads further geographically, we will need to reevaluate production capacity.” Several Texas lawmakers recently introduced the STOP Screwworms Act, which directs the USDA to open a new factory, but the whole process could still take years. “The facility needs to start tomorrow,” Cockrell said.

The U.S. cattle industry is unprepared for the screwworm’s return, he said, rattling off more reasons: Certain drugs to treat screwworm infection are not licensed in the U.S., having been unnecessary for half a century. Ranches used to employ 50 cowboys who regularly inspected cattle, and now they might have only five. And routine industry practices such as branding and ear tagging leave the animals vulnerable to screwworm infection. To face the screwworm, the cattle industry will have to adapt quickly to a new normal. The parasite could propel beef prices, which are already sky-high due to drought, even higher.

How screwworms managed to jump the barrier in 2022 is not fully clear. But in the years immediately before, the coronavirus pandemic reportedly created supply-chain snarls at the fly factory in Panama and disrupted regular cattle inspections that might have set off the alarm bells earlier. And the border between Panama and Colombia got a lot busier; the Darién Gap, once a notoriously impenetrable jungle, became a popular route for migrants.

Still, the screwworm advanced relatively slowly through Panama and Costa Rica for the first couple of years. Then it hit Nicaragua, and over just 10 weeks in 2024, it shot from the country’s northern border through Honduras and Guatemala to reach Mexico. This rapid advance was because of the illegal cattle trade, Jeremy Radachowsky, the director for Mesoamerican and the Western Caribbean at the Wildlife Conservation Society, told me. His organization has tracked the practice in Central America, where 800,000 cattle a year are raised illegally in nature reserves and then smuggled by boat and truck up to Mexico. This allowed the screwworm to spread much faster than it can fly. The line of new screwworm cases followed known smuggling routes, Radachowsky said. The constant northward movement of infected cattle could now make re-eradication more difficult. It’s like trying to empty a pool when “the spigot’s still open,” he said.

Decades of screwworm-free existence meant that even ranchers, whose livelihoods are directly affected, were slow to recognize the growing emergency. “We were so successful that literally people forgot,” a U.S. official in Central America familiar with the situation (speaking anonymously due to the delicate politics involved) told me. Inspections, timely reports of infection, and restrictions on cattle movement are important pieces of eradication, in addition to the release of sterile flies.

Over the years, scientists have also proposed more advanced ways of controlling the screwworm through genetics, though none is yet ready for prime time. The USDA supported research by Max Scott, an entomologist at North Carolina State University, to create a male-only strain that could reduce the number of flies needed for dispersal, but funding ended last summer. He has also proposed using gene drives, a still-controversial technique that could rapidly “drive” genetic material that makes females sterile into the wild population. The USDA wasn’t interested, he told me. (A spokesperson says the USDA “continues to research and investigate new tools,” including genetically engineered male-only screwworms.) But he did strike up a collaboration several years ago with scientists in Uruguay studying a gene drive for sterile screwworms.

Uruguay is interested because it never got to benefit from screwworm eradication; the country is located about halfway down South America, deep in screwworm territory. A retired USDA scientist, Steven Skoda, told me that he and his colleagues used to dream of “a world totally free of screwworm.” But eradication never reached South America, and now even the barrier protecting North America is no longer intact. The campaign to push screwworms from the south of Mexico—roughly where the parasite is right now—to the southern edge of Panama took 21 years. The way things are going, Cockrell said, some of his longtime colleagues in Panama might not see screwworms eradicated again in their country in their lifetime.

Robert F. Kennedy Jr. has had a long love affair with junk science, and as secretary of Health and Human Services, he has embraced it once more, most brazenly to justify his false claims that vaccines cause autism. Last week, he brought yet another shoddily designed study to a different fight. In a Senate Committee hearing, he cited a report that few scientists would recognize as science in order to justify an FDA safety review of the drug mifepristone, which is used in the majority of abortions in the United States.

President Donald Trump had previously asked HHS to study the drug’s safety, and Kennedy emphasized at the hearing that a review of the drug would be a top FDA priority. The unusually high rate of adverse events identified in the report, he noted, “indicates that at very least, the label should be changed.” In other words, the top U.S. health official is prepared to rework—based at least in part on a poorly designed report that has not undergone scientific review—the government’s official guidance on a widely used drug.

The report that Kennedy cited was posted late last month to the website of the Ethics and Public Policy Center, a Washington, D.C.–based think tank focused on “pushing back against the extreme progressive agenda while building a consensus for conservatives,” according to its website. The study’s authors, Jamie Bryan Hall, EPPC’s director of data analysis, and Ryan Anderson, the organization’s president, are not health experts, and neither seems to have a record of publishing scientific research through peer review. Their methods deviated wildly from what is standard in the world of health research, and so, predictably, did their conclusions: In sharp contrast to dozens of trials conducted around the globe over decades, the EPPC report determined that mifepristone is a danger to women.

The EPPC has written that its report “presents a careful and conservative assessment of abortion pill safety.” However, the study lacks basic transparency about how that assessment was made. The authors relied on data from an insurance database that, according to the report, included more than 800,000 mifepristone abortions from 2017 to 2023. But the authors don’t actually say which database they used, so “there’s no way for anybody to try to re-create their analysis to see if they receive the same results,” Sara Redd, of the Center for Reproductive Health Research in the Southeast at Emory University’s Rollins School of Public Health, told me. (In an email, Hunter Estes, EPPC’s communications director, told me that the center’s contract with their data vendor prevents EPPC from sharing the name of the database or even of the vendor. But, he added, “this insurance data is available from approximately a dozen data brokers and is widely used by researchers and health professionals.”)

[Read: The other abortion pill]

The report also took some peculiar methodological steps to arrive at its conclusions. One of its key findings is that more than 10 percent of people who take mifepristone experience what the study refers to as “serious adverse events.” (A variety of studies put the rate of significant adverse events from medical abortions involving mifepristone at less than 0.3 percent, which makes the drug safer than Tylenol and Viagra.) But the EPPC study’s unusually wide-ranging criteria for defining those events raise a lot of questions. The researchers counted ectopic pregnancy as an adverse event, arguing that doctors should have ruled it out before prescribing mifepristone. (The American College of Obstetricians and Gynecologists acknowledges that mifepristone can be dangerous in cases of ectopic pregnancy but says that ruling out the rare condition—a process that involves an ultrasound—is unnecessary for most women taking the drug.) The authors counted episodes in which a surgical procedure was required to complete the abortion after mifepristone—patients require additional treatment in about one in 20 cases, so the FDA considers this a recognized outcome rather than an adverse effect. They counted “other life-threatening adverse events,” including heart problems and mental-health concerns, that women in the study experienced in the weeks after the abortion—which may have had nothing to do with mifepristone.

They also counted “serious” events documented during emergency-room visits made within 45 days of a patient taking mifepristone. However, the report doesn’t fully explain how they knew that those events were connected with mifepristone, and to judge which ones counted as “serious,” they used a scale designed for cancer research, which has not been validated for use in studies of abortion care. Loosely counting emergency-room visits could artificially inflate the estimate of risk associated with getting an abortion, Ushma Upadhyay, an epidemiologist and a reproductive-health researcher at UC San Francisco, told me: In a study she led of abortion-related emergency-room visits from 2009 to 2013, half of patients had such mild symptoms that they did not need any treatment. She also said that the authors did not effectively distinguish between the outcomes of abortions and of miscarriages treated with mifepristone, or between normal amounts of post-abortion bleeding and severe hemorrhage.

In the weeks following the report’s publication, EPPC published two follow-up documents with more details about the study’s methodology, which experts told me are still not convincing. As the documents explained, the authors relied on diagnostic codes to separate miscarriages, which are often also treated with mifepristone, from abortions—a practice that may yield imprecise results. The report included only suicidal and homicidal ideation among mental-health diagnoses categorized as serious adverse events—but that still does not prove that those diagnoses were connected to an abortion, Redd told me. It used “only codes related to hemorrhage or serious bleeding (according to the FDA definition)”—which would still not be enough to distinguish between the normal amount of post-mifepristone bleeding and something more serious, Upadhyay said.

[Read: A possible substitute for mifepristone is already on pharmacy shelves]

According to EPPC, peer review of the report was not possible due to “extensive pro-abortion bias in the peer-review process,” but a group of data scientists, analysts, and engineers “conducted and validated” the project, with assistance from doctors. None of their names appears on the report. When I asked about that decision, the EPPC representative wrote, “It is routine for individuals with controversial opinions to be subjected to a range of personal and professional attacks, including threats of violence in their own homes.”

So far, the most prevalent attacks on the study have been about its substance. Alice Mark, an ob-gyn and the medical director of the National Abortion Federation, told me that “to call it a study dignifies it too much.” Some anti-abortion advocates, too, have cautioned against overstating the study’s rigor: Earlier this month, Politico reported that Christina Francis, the CEO of the American Association of Pro-Life OBGYNs, said on a private Zoom call with anti-abortion leaders that although the report contains credible data and should inspire further research, it is “not a study in the traditional sense” and “not conclusive proof of anything.”

Anti-abortion activists have long seen mifepristone as a problem. In the years since the Supreme Court’s 2022 decision to overturn the national right to abortion, abortions have increased in part due to a 2021 FDA decision that allowed mifepristone and misoprostol (a drug often used in parallel for abortion) to be prescribed via telehealth and mailed. According to reporting by Politico, questioning mifepristone’s safety is part of a larger strategy called “Rolling Thunder” that aims to cut off that access. High-quality data have failed to validate those questions, so second-rate research has often been used to make the case against mifepristone. In 2023, for example, a federal judge ruled that mifepristone should be taken off the market by citing low-quality studies that reported adverse effects from mifepristone. (The Supreme Court later threw out the lawsuit on procedural grounds.) Due to their “lack of scientific rigor,” two of the studies cited were ultimately retracted by the journal that had published them.

[Read: Anti-abortion conservatives’ first target if Trump returns]

When, in the past, the FDA has evaluated mifepristone’s safety—which it’s done several times since mifepristone’s initial approval, in 2000—it has expanded access to mifepristone rather than curtailed it. If the agency evaluates mifepristone again, and its staff are allowed to independently assess the science, the FDA could loosen its rules for mifepristone even more, Elizabeth Raymond, an ob-gyn and a researcher who specializes in mifepristone safety, told me. Plenty of data support using mifepristone later in pregnancy than is currently approved, for instance.

But Upadhyay told me she worries that FDA Chief Marty Makary—who has previously claimed that fetuses can “resist” the tools of abortion by 20 weeks of gestation—or Kennedy could put their thumb on the scale to restrict mifepristone access, regardless of what FDA staff recommend. “I don’t want them to do a review, because I don’t trust them to base any decisions they make on science,” Upadhyay said. (HHS and the FDA did not answer my questions about the FDA’s plans to review mifepristone safety on the basis of the EPPC report. In an email, an HHS spokesperson told me of the FDA, “The agency rigorously evaluates the latest scientific data, leveraging gold standard science to make informed decisions.”)

Although Kennedy has said that he reads scientific papers critically for a living, his approach to the medical literature most resembles “an extreme version of what lawyers do to defend a client: create a narrative and then find supporting evidence,” Robert Califf, who led the FDA under Presidents Joe Biden and Barack Obama, told me an email. The scientific method involves the opposite: constructing a hypothesis and trying to disprove it with an open mind. When different people conducting the same experiment come to the same conclusion, it’s not a sign of a shared ideology; it’s a sign of a shared reality.

Photographs by Evan Jenkins

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A Wednesday morning in May is a strange time to be trick-or-treating—especially if you’re an adult wearing business casual. The Indiana Convention Center had just opened to visitors for the second day of Sweets & Snacks, the largest gathering of the candy and snack industry in North America. Along with nearly 15,000 other attendees, I went from booth to booth trying samples. By 10:40, I was sipping a complimentary blue-raspberry-watermelon Icee while a woman to my right took a selfie with Mr. Jelly Belly. At the Slim Jim booth a few feet away, a bunch of people in blazers gathered around a smorgasbord of meat sticks. The only thing that could get between attendees and their snacks was the occasional free beer or run-in with a mascot. At one point, the Jack Link’s Sasquatch attempted to steal my Entenmann’s mini muffins.

I had come to Sweets & Snacks to taste the future of junk food. The annual conference is the industry’s most prominent venue to show off its new products. Judging by my three days in Indianapolis, the hot new trends are freeze-dried candy and anything that tastes vaguely East Asian: think “matcha latte” popcorn. But right now, that future looks shaky, particularly for confections. Candy embodies everything that Health and Human Services Secretary Robert F. Kennedy Jr. believes is wrong with the American diet. It’s mainly sugar (which Kennedy has called “poison”), counts as an ultra-processed food (which Kennedy has called “poison”), and is often colored with synthetic food dyes (which Kennedy has called “poison”). Last month, RFK Jr. announced a goal of eliminating synthetic food dyes by the end of 2026, a major threat to an industry predicated on making bright, eye-catching treats. In an email, an HHS spokesperson said that “Secretary Kennedy has been clear: we must build a healthier future by making smarter choices about what goes into our food.” The spokesperson added that “the secretary is committed to working with industry to prioritize public health.”

At Sweets & Snacks, I did not encounter an industry that was gearing up for change. Instead, it was RFK Jr.’s worst nightmare: an unabashed celebration of all things sugary, artificial, and indulgent. On the convention floor, it was hard to find a single product—beyond the litany of meat sticks and the occasional mixed nut—that would get RFK Jr.’s stamp of approval. Even a finalist for the convention’s annual salty-snack award, Vlasic Pickle Balls, contained tartrazine, a synthetic yellow dye that Kennedy has specifically bashed. As I stuffed my face with sugary treats, I began to wonder: Was the industry delusional about Kennedy, or the other way around?

RFK Jr.’s presence was conspicuously absent from the moment I arrived in Candy Land. “Anywhere over here is fine,” I told my Lyft driver as we pulled up to a hulking red M&M. Candy companies have already been investing in healthier options: Mars bought snack-bar maker Kind in 2020 and proudly displayed the bars in a booth alongside their more traditional M&Ms, Skittles, and Starburst. But the only vague mention of the looming RFK Jr. threat on the convention floor was a billboard posted by the conference’s organizers, the National Confectioners Association (NCA). It reiterated the candy lobby’s longstanding message: Candy shouldn’t be lumped together with other ultra-processed foods, because it is an occasional indulgence.

It’s hardly surprising that candy companies aren’t abruptly changing their products in response to pressure, even when it’s coming from the country’s top health regulator. Americans bought $54 billion worth of these treats last year. In April, the health secretary boasted that the U.S. food industry had “voluntarily agreed” to remove synthetic dyes from their products, but judging from the items on display at Sweets & Snacks, the candy industry has little interest in fulfilling that promise anytime soon. When I asked Christopher Gindlesperger, NCA’s senior vice president of public affairs and communication, if the candy industry had an understanding with RFK Jr. to eliminate synthetic dyes voluntarily, his response was simple: “No.”

Some of the discussions around dyes are understandably frustrating for the industry. Federal regulators haven’t done the sort of thorough academic evaluation of these dyes that’s typically expected before trying to push them out of the food supply. (The state of California released its own evaluation in 2021 and found that “synthetic food dyes are associated with adverse neurobehavioral outcomes in some children.”) At the same time, the candy industry isn’t doing much to signal that it recognizes the growing concern over these ingredients. It’s hard to be sympathetic toward companies that purposefully market unhealthy products to children through the use of mascots and funky colors. I was taken aback when I stumbled upon a Despicable Me–branded coloring set that let kids color in a cookie with a marker filled with tartrazine.

The industry’s efforts to uphold the status quo are risky. If Kennedy is intent on enforcing an actual ban on synthetic food coloring, it could have a monumental impact. Making the switch to natural colors is not as simple as FDA Commissioner Marty Makary suggested when he told food makers during a press conference last month to just start coloring their products with fruit and vegetable juices. Natural colors are typically more expensive, and they’re far more finicky than their synthetic alternatives. Moisture, pH, and even light can cause the dyes to degrade. A naturally colored M&M might be red when it leaves the factory, but if it sits in your pantry too long, it could take on a not-so-appetizing color. There’s a question, too, of whether there are even enough fruits and vegetables in the world to supply the food industry with enough natural dye to serve the massive U.S. market. “The amount of crops that go into some of these dyes is just so high that we don’t necessarily have these crops planted,” Renee Leber, a food scientist at the Institute of Food Technologists, told me.

Here’s yet another concern: Natural dyes may alter the taste of certain treats. The company behind Dum-Dums lollipops has suggested that replacing artificial red dye with beet juice could make its red lollipops taste like beets. (That doesn’t mean it can’t be done. Many companies already sell products in Europe without synthetic dyes. And Katjes, a German company sandwiched between Jack Link’s and Harvest Snaps, was giving away its rainbow unicorn gummies, which looked plenty eye-catching to me, despite being colored solely with fruit and vegetable juices.)

Food dyes are only one part of the RFK Jr. threat that the candy industry faces right now. Yesterday, the Trump administration’s “MAHA Commission” released a much-touted report on childhood health, calling out sugar and ultra-processed foods as a major contributor to the youth chronic-disease problem. When I spoke with Gindlesperger, he was quick to point out that candy is far from the biggest cause of America’s sugar problem. (Sweetened drinks are.) “People understand that chocolate and candy are treats, and consumers have carved out a special place for them in their lives,” he said. He cited an NCA-funded analysis of CDC survey data, which showed that people in the United States eat roughly 40 calories a day of candy.

But that analysis doesn’t distinguish between kids and adults. Data are scant on children’s consumption of candy, though if you’ve walked with a kid down a candy aisle, you can probably tell that most haven’t fully grasped that gummy worms are meant to be an occasional indulgence. “It’s really difficult for a child who has access to candy to stop eating it,” Natalie Muth, a pediatrician and dietitian, told me. Candy consumption among kids, she added, is a “big problem.”

In a country where nearly 20 percent of children are obese, more needs to be done to protect people from the candy industry’s worst tendencies. But mandating any such changes will be incredibly difficult for RFK Jr. To ban tartrazine alone, the FDA would need to compile a docket of information demonstrating its harm, issue a draft regulation, take public comments, and then finalize the regulation. Gindlesperger said the candy industry is waiting for the FDA to formally review the safety of the dyes it takes issue with: “We support and would welcome that review.” Even after all those steps, the food industry can—and likely would—sue. There’s even less precedent for cracking down on sugar. Kennedy has acknowledged that a sugar ban is unlikely, and instead has argued for more education about the risks of having a sweet tooth.

If Kennedy succeeds in ushering in actual reform, the “Make America Healthy Again” movement won’t truly revolutionize the American diet until it figures out how to redefine our relationship with certain foods. Whether Kennedy likes it or not, candy is part of our national psyche. He can’t simply wave a wand and ban trick-or-treating or candy canes. Over the course of three days, I saw grown adults fill multiple shopping bags with free treats. Candy companies displayed bags of their products to show retailers what they’d look like in a store, and the bags literally had to be taped down to avoid getting swiped. (Some still were.) I learned that attendees commonly bring a second suitcase just to haul their loot home.

Nothing quite epitomized the affection for treats like the impromptu dance party that broke out near the close of the conference. Chester Cheetah, Ernie the Keebler Elf, the purple Nerd, the Lemonhead, Bazooka Joe, Clark Cheese Head, and Chewbie, the Hi-Chew mascot, all began to sway in unison to a marching band that was hired to entertain guests. Conference attendees clamored to get a video of the spectacle and snap a selfie with their favorite mascot. The moment was absurd, and funny, and more than a little embarrassing. Still, I couldn’t help but pull out my own phone and crack a smile. Perhaps it was nostalgia for bygone Halloween nights, or maybe all the sugar was just getting to my head.

Long before he joined the FDA to run the center that regulates vaccines, Vinay Prasad argued against COVID shots for kids. Among his many criticisms of the United States’ approach to combatting the disease, Prasad has insisted that pediatric vaccines have few benefits for kids—and has maintained that the FDA should never have authorized COVID boosters for them, that the CDC should never have recommended those shots, and that “it is malpractice for a doctor to recommend the booster to children.” And he has advocated for the CDC removing the COVID vaccine from the childhood-immunization schedule.

Just two weeks into his tenure as the FDA’s new vaccine czar, Prasad seems to be taking the first steps toward turning this rhetoric into reality.

Yesterday, he and Marty Makary, the FDA’s new commissioner, announced a new framework for COVID-19 vaccines: The agency will no longer green-light new formulations of COVID shots for healthy people under 65, unless companies submit data from new clinical trials that prove the shots’ worth—an unusual ask, experts told me, for vaccines that have already been through the sorts of rigorous studies that scrutinize their safety and effectiveness, and received the agency’s authorization or approval. When describing this shift in an article published in The New England Journal of Medicine, as well as in a livestreamed FDA press conference, Prasad and Makary—neither of whom has formal training in infectious disease or vaccinology—focused primarily on the implications for COVID boosters for young, healthy adults. But experts outside of the agency told me that the policy could also prevent most American children from accessing their initial series of COVID vaccines—essentially guaranteeing that kids will first encounter the virus without protection.

At the press conference, Prasad once again criticized the CDC’s 2023 decision to add COVID vaccines to the childhood-immunization schedule, which currently recommends the shots as a two- or three-dose series as early as six months of age. He and Makary did not, however, explicitly address whether their new framework will ultimately cut healthy, young kids off from an initial series of COVID vaccines. (In theory, children with certain preexisting conditions should remain eligible.) But several vaccinologists, pediatricians, epidemiologists, and vaccine-policy experts told me that the agency’s stance on the matter appeared to be leaning toward yes, at least without new data from companies that will be extraordinarily challenging to collect, if companies try to collect such data at all.

When I contacted the FDA seeking clarification on whether kids will continue to have access to their first COVID vaccines, I did not receive a response. When reached for comment, Emily G. Hilliard, HHS’s press secretary, did not answer my questions about the primary series for kids, but said via email that “a rubber-stamping approach to approving COVID boosters in perpetuity without updated clinical trial data under the Biden Administration is now over.”

From the earliest days of the pandemic, children have been afflicted by severe COVID at lower rates than adults. “We certainly did not see as much pediatric disease as we saw adult disease,” Buddy Creech, a pediatrician and the director of the Vanderbilt Vaccine Research Program, told me. But kids also were not spared the virus’s worst effects. After the pandemic began, the virus became a top-10 cause of death among American minors, and it has killed more than 1,000 children, many of whom had no preexisting health conditions.

Kids, like adults, are also vulnerable to long COVID, albeit at lower rates. And they have experienced their own unusual, terrifying manifestations of disease, including the inflammatory condition MIS-C. (MIS-C has become much less common in recent years, but is poorly understood and could return with future variants, Creech told me.) Disease that manifests rather mildly now may change as the virus continues to evolve. And generally speaking, among kids, “the younger the child, the higher the risk for severe disease,” Sallie Permar, the chair of pediatrics at Weill Cornell Medicine, told me.

Yesterday, at the press briefing, Prasad noted that COVID hospitalizes children far less often than it does older adults. But diseases also don’t have to be catastrophically deadly to warrant a childhood-vaccination policy, Ofer Levy, the director of the Precision Vaccines Program at Boston Children’s Hospital, told me. The death rate for chicken pox, for instance, is extremely low, but the vaccine is available to, and recommended for, all children—not just those with preexisting conditions. And COVID vaccines for kids, especially in the smaller doses tailored to the youngest age groups, are “among the safest we know of,” Permar told me. Although myocarditis is a rare side effect of COVID vaccines, it is primarily a concern for adolescent boys and young men, rather than very young kids; in general, the shots’ side effects include redness at the injection site, soreness, and fever.

In short, kids are at risk from the virus, and a safe shot can lower that risk. Now, though, per the FDA, apparently “the risk isn’t high enough,” Grace Lee, a pediatrician at Stanford, told me. (During the early years of COVID, Lee chaired the CDC’s advisory committee on immunization practices, or ACIP, which recommended the vaccines for children.)

Prioritizing vaccination for those at highest risk of a particular disease, as the FDA’s new policy would, is sensible. Focused messaging can be an especially powerful way to increase uptake, Creech pointed out. That is sorely needed for people over 65, who are among the groups at greatest risk from the virus and aren’t staying up to date on their shots. Many of the experts I spoke with also said that recommendations that counsel repeat shots for most Americans don’t make as much sense as they used to: Much of the population has immunity from both vaccines and infections, and recent COVID waves have been far more blunted than they were in the past. ACIP was already mulling limiting the recommendations for annual COVID shots to only those at highest risk.

But the question of whether most Americans should be getting COVID shots regularly is fundamentally different from the question of whether healthy kids should be able to get a primary series of shots early in life. Today’s children will likely have to contend with different versions of this virus for the rest of their lives, and to take away to option of gaining protection ahead of disease “is a myopic view of COVID prevention,” Gregory Poland, a vaccinologist and the president of the Atria Research Institute, told me. This country generally does vaccinate against every vaccine-preventable disease that affects children in the U.S., as early as is practical and possible. At the very least, “parents should have an option,” Lee told me.

Without an explicit FDA policy addressing the primary vaccine series for kids, the experts I spoke with said they weren’t sure how quickly access to the shots would dwindle for children. Current COVID vaccines for children could remain available until the next update. But if the CDC alters the recommendations for children, that could tank insurance coverage for the shots, or pediatricians’ willingness to stock them. “I think this next year is going to be full of confusion,” Jason Schwartz, a vaccine-policy expert at Yale, told me. With so much in limbo, manufacturers may not want to keep up production of pediatric shots at all, which are formulated differently and in smaller doses. And pediatric COVID vaccines remain under emergency authorization—which the FDA could still strip entirely.

The FDA has, in theory, laid out a path for future approvals of COVID vaccines, including for healthy young kids—through new clinical trials. But those sorts of studies are expensive and laborious—particularly when they involve children, who get very sick at lower rates than adults and whose parents might not want to enroll them in studies that could offer them only a placebo, Lee told me. The new framework also calls for trials to measure whether vaccines can reduce the risk of symptomatic cases of COVID. But because the shots work best against severe disease, that criterion could set up new shots to fail.

Prasad and Makary stressed that many other countries, including much of Europe, have long since abandoned recommendations that healthy children get COVID shots. But “it’s apples and oranges,” Theresa Chapple, an epidemiologist who is on the board of Vaccinate Your Family, told me. “We don’t have similar health-care systems, and we don’t have similar proportions of healthy people.” At baseline, Americans are at more risk—which warrants more baseline precaution.

In the past, the U.S. government has seen fit to restrict or pull vaccines only under extraordinary circumstances: major new safety concerns, a better immunization option, eradication of disease. And those decisions have generally come only after political leaders consulted multiple scientific experts in the field, which Prasad and Makary chose not to do through their agency’s typical channels. (The FDA’s panel of independent vaccine experts is scheduled to meet tomorrow.) Rather, political appointees with preexisting opinions on COVID vaccines appear to have enacted policy unilaterally. Prasad and Makary publicly went after COVID boosters. But kids’ first defenses against the virus are likely to be that attack’s collateral damage.  

The lab-leak theory of COVID-19’s origins comes in many forms. Here is Donald Trump’s: A scientist in Wuhan walked outside to have lunch, maybe with a girlfriend or something. “That’s how it leaked out in my opinion, and I’ve never changed that opinion,” the president said earlier this month at a press event. Whether something like this really happened was, until this year, a subject of lively debate. These days, it’s being presented as official history. Yes, COVID did come out of a Chinese lab, White House Press Secretary Karoline Leavitt told reporters shortly after Trump’s inauguration. “We now know that to be the confirmable truth.”

Of course, we don’t really know that, and they don’t know it either. Director of National Intelligence Tulsi Gabbard, who has convened yet another lab-leak investigation at Trump’s behest (after many other intelligence assessments led to split results), could only dance around the matter in an interview with Megyn Kelly earlier this month. Has some new and final proof been found? Kelly asked. Gabbard responded: “We are working on that with Jay Bhattacharya,” the director of the National Institutes of Health, “and look forward to being able to share that hopefully very soon.” (Gabbard’s office did not reply to a request for comment.)

Any hedging on the matter of pandemic origins represents a standard view among the experts: We simply aren’t sure. In reporting on this question for the past few years, I’ve spoken with some scientists and pandemic-origins investigators who are confident the coronavirus came out of a Wuhan lab, and with some who say they’re nearly certain that the virus spread to humans from a market stall. I’ve also heard from many others whose appraisals of the odds fall somewhere in between. Their only common ground may be the single plain acknowledgment that the evidence we have is incomplete.

But, despite the well-established data gaps—and in willful disregard of them—the lab-leak theory has become a MAGA theorem. Adherence to it is now a central tenet of the Trump administration: a shibboleth for loyalists, an animating grievance, and, in recent weeks, a stated rationale for punitive reforms. Earlier this month, when the White House proposed an $18 billion cut to the nation’s budget for biomedical research, the lab-leak theory—described as “now confirmed”—was given as a pretext.

There are many reasons to regret this shift toward artificial certainty, starting with the fact that whatever nuance now attached to the topic of pandemic origins has been hard-won. For much of 2020, a different bullheadedness prevailed: Invocations of the lab-leak theory were often tarred as right-wing propaganda, or even racist lies. At the start of Joe Biden’s presidency, “there was a clear and almost overwhelming leaning towards natural origin,” David Relman, a Stanford microbiologist and former member of the National Science Advisory Board for Biosecurity who has long maintained that a laboratory origin is more likely, told me. This bias weakened over time, as the theory came to have more distance from the Trump administration, and more suggestive bits of circumstantial evidence accrued. In the spring of 2023, the COVID-19 Origin Act, which demanded the declassification of all lab-leak-related intelligence, passed without a wisp of opposition, and in 2024, Relman himself was detailed to the White House as a senior adviser working on pandemic preparedness. “There was a palpable shift to the middle,” he said.  

But this equanimity has proved to be short-lived. According to the new administration and its supporters, the laboratory origin is presumptively correct. On covid.gov, which until last month offered only basic patient information (“If you test positive for COVID-19, talk to a doctor as soon as possible”), LAB LEAK now appears in jumbo font across the top—with Trump himself emerging from the gap between the B and L, as if he’d just leaked out himself. “The true origins of COVID-19,” the government website says, beside his foot.

Declaring fealty to this point of view has now become a sacred rite within the GOP, not unlike endorsement of the claim that the 2020 election was a fraud. Plenty of Trump’s most senior appointees have averred that COVID started in a lab. Secretary of Homeland Security Kristi Noem described it as “the truth.” FDA Commissioner Marty Makary has claimed that a laboratory origin is a “no-brainer,” and described it falsely as “now the leading theory among scientists.” Bhattacharya said at an NIH town hall on Monday that he believes the coronavirus was released from a lab, and that it derived from U.S.-funded research. The DHS, FDA, and NIH did not reply to requests for comment.

Health and Human Services Secretary Robert F. Kennedy Jr. has staked out the most extreme position of the bunch, publicly declaring that “SARS CoV-2 is certainly the product of bioweapons research.” As of January, the entire U.S. intelligence community disagreed with this assessment. In an email, an HHS spokesperson told me that Americans “will no longer accept silence, censorship, or scientific groupthink” and “deserve the truth.”

In the background, too, the administration has looked to bring other hard-liners on the lab-leak theory into the fold. Robert Kadlec, for instance, has been nominated for a role at the Department of Defense. A veteran of the first Trump administration who was instrumental in the management of Operation Warp Speed, he is also the author of a report that argues SARS-CoV-2 might have been developed by the Chinese military as a bioweapon that could lower American IQs by fogging up our brains with long COVID. (Kadlec told me that he doesn’t think COVID would be a major part of his portfolio, if he were confirmed—but “it will have relevance with the biosurveillance work that may be done,” he said.)

A former senior scientist at NIH told me about two others whose potential roles in government have not previously been reported. The first is Alina Chan, a molecular biologist at the Broad Institute of MIT and Harvard, the author of Viral: The Search for the Origin of COVID-19, and a dogged advocate for more vigorous investigations of the lab-leak theory and tighter restrictions on virology research. Chan confirmed to me that she is in discussions for a role at the NIH. “I haven’t committed to anything,” she told me, “but I do feel like now that we’ve reached this point, I feel that this is probably the most important thing that I should be doing in my life—doing as much as I can to help the U.S. government prevent future catastrophic lab leaks.”

The former NIH scientist, who requested anonymity in order to preserve professional relationships, also said a contract was under consideration for Bryce Nickels, a Rutgers geneticist and Bhattacharya’s friend and former podcast co-host. Nickels has been notably aggressive on the lab-leak theory, and as an advocate for better oversight of research that could lead to the production of more dangerous pathogens. In his posts on social media, Nickels has called Anthony Fauci a “monster” and maintained that the U.S. is in the business of developing “bioweapon agents.” (Nickels did not reply to questions for this article.)

In principle, the arrival of this lab-leak coterie in Washington could have marked a useful shift in the study of pandemic origins. If the old guard in public health was at times inclined to paper over uncomfortable debates, this new one might be zealously transparent. Chan, for instance, told me that she’d like to see investigators take a closer look at documents and correspondence from EcoHealth Alliance, the NIH-funded nonprofit that was working with the Wuhan Institute of Virology, and spend more effort trying to nail down the very first cases of disease in China. She also thinks the government should release more details of the intelligence community’s assessments, which might explain why different agencies and offices have come to different answers as to what is most likely to have occurred. (The FBI, CIA, and Department of Energy lean toward a laboratory accident of some kind. Five others, including the National Intelligence Council and the Defense Intelligence Agency, are inclined the other way.)

But this administration seems unlikely to make much progress on this front. If anything, its policies and proclamations have only made the subject more intractable. Even before Trump took office, many scientists were reluctant to engage with the topic, for fear of being drawn into what has been a very public and vituperative debate. Now that worry must be multiplied a hundred times. In recent months, the NIH has terminated grants that run afoul of the government’s positions on diversity and gender, and shut off funding to entire research universities. It will soon end the system that U.S. researchers use to share grant funding with foreign collaborators, and has begun suspending collaborations overseas. The risks of stepping out of line have never been so salient.

In the meantime, new government restrictions inspired by the lab-leak theory could serve to make it even harder to fill in the remaining details of what happened in Wuhan. Michael Worobey, an evolutionary biologist at the University of Arizona who has published a string of papers laying out an aggressive case for the market origin, told me that he’d like to see more sampled DNA from wild populations of civets, raccoon dogs, and bamboo rats throughout China. But this sort of work would require close collaboration with Chinese researchers, at just the time when those collaborations are being scrutinized or canceled.

“The administration is developing a very adversarial relationship with the scientific and technical communities,” Filippa Lentzos, a biosecurity researcher and professor at King’s College London, told me. “It’s not a facts-based discussion. There are facts from one side, but not from the other side.” This climate will tend to undermine the work of encouraging more prudence in the labs of those who study risky pathogens, she said. As for the COVID-origins debate itself, she does not expect a satisfying answer. “I think it’s kind of a lost cause.”

Either way, by tying budget cuts and other new restrictions to the lab-leak theory, the administration seems intent on punishing an enormous swath of biomedical researchers for the actions of the tiny handful whose work could even theoretically be tied to the pandemic. “This is the most enormous case of baby and bathwater that I have ever seen,” Relman told me. “The baby is just being shoved down the drain.”

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It took just a few hours for devotees of the “Make America healthy again” movement to question former President Joe Biden’s prostate-cancer diagnosis. Tumors of the prostate are the most common serious malignancy identified in men: Even aggressive ones like Biden’s are diagnosed roughly 25,000 times a year in the United States. Although Biden’s condition is conventional, a certain segment of the public has been beguiled into blaming mainstream medicine for every unexpected death or health-related tragedy it comes across. The anti-vaccine community, including the group formerly led by Health Secretary Robert F. Kennedy Jr., has spent years promoting the idea that mRNA vaccines for COVID regularly push tumors into overdrive. (Rare anecdotes aside, there is no evidence to support this fear.) Now, predictably, the claim is cropping up again on social media. “Prostate cancer takes years to metastasize to bone unless super aggressive or turbo cancer,” the Kennedy-endorsed physician Craig Wax suggested.

That an 82-year-old man who had aged out of prostate-cancer-screening tests has been found to have an advanced malignancy should not be surprising. In my experience as a doctor who diagnoses cancer, many tumors are discovered out of the blue. Prostate cancer in particular may not become apparent until an individual goes to his doctor with a minor complaint—in Biden’s case, urinary symptoms, according to the announcement—only to have further testing discover the worst. (Biden’s cancer isn’t curable; people with Stage 4 disease like his live for about three years on average—although the outlook is worse for men who are more than 80 years old.)

Cancer is an enigmatic disease, one that is simultaneously influenced by genetics, environment, personal habits, the aging process, and—not to be discounted—bad luck. But its muddled nature can be uncomfortable for those who share the view that nearly all sickness is preventable with virtuous behavior and a clean environment. According to Kennedy, the current leader of the U.S. health-care system, tumors are a product of not only the vaccines in our arms, but also the fluoride in our water, the toxins in our school lunches, the signals from our phones, and surely many other ubiquitous aspects of modernity. Indeed, in MAHA land, cancer is not just a misfortune, but a cover-up. Before he became health secretary, Kennedy ominously suggested that doctors might find its cause in the “places they dare not look.”

[Read: The inflated risk of vaccine-induced cardiac arrest]

It’s not just Kennedy. Trump’s health-care team routinely draws from the logic of this wellness-paranoia complex. Last year, Marty Makary, who has since become the FDA commissioner, told a group of MAHA wellness influencers convened by Senator Ron Johnson that cancer is a consequence of “low-grade chronic inflammation” induced by a poisoned food supply. (Years ago, he also speciously declared that undetected medical errors were a leading cause of death.) Casey Means, Trump’s new nominee for surgeon general, has claimed that “the biggest lie in healthcare” is that high blood sugar, malignant tumors, and clogged arteries “are totally different diseases requiring separate doctors and pills for life.” The truth is “simpler than we are told,” she said. (Buy her book to find out what it is.) And Mehmet Oz, the former lifestyle guru and current Medicare administrator, recently informed Americans, “It’s your patriotic duty to be as healthy as you can. It’s our job to help you get there, make it easy to do the right things.” Never mind that you can do everything right and still get sick. (For now, none of the administration’s major health officials has weighed in on Biden’s diagnosis.)

[Read: Did a famous doctor’s COVID shot make his cancer worse?]

Joe Biden is no stranger to tough luck. His son Beau died of a brain tumor at age 46 in 2015, leading to Biden’s participation in a government-funded “cancer moonshot” to combat the condition. The moonshot initiative was an old-fashioned approach to medicine, one that sought to ameliorate illness through advances in science and technology. RFK Jr. and his MAHA acolytes are naturally suspicious of this approach. Now their weird discomfort with disease—and their outré views on cancer in particular—is being refracted through a sea of false, indecent speculations. No, Biden’s cancer was not “courtesy of the mRNA shot.” One can only hope that the government’s bevy of vaccine skeptics will be able to resist the siren’s call to join in saying otherwise.