In less than two weeks, you could walk out of a pharmacy with a next-generation COVID booster in your arm. Just a few days ago, the Biden administration indicated that the first updated COVID-19 vaccines would be available shortly after Labor Day to Americans 12 and older who have already had their primary series. Unlike the shots the U.S. has now, the new doses from Pfizer and Moderna will be bivalent, which means they’ll contain genetic material based both on the ancestral strain of the coronavirus and on two newer Omicron subvariants that are circulating in the U.S.
These shots’ new formulation promises some level of protection that simply hasn’t been possible with the original vaccines. “A bivalent vaccine will have some benefit for almost everybody who gets it,” Rishi Goel, an immunologist at the University of Pennsylvania, told me. “How much benefit that is, we’re still not exactly sure.” People who aren’t at high risk could end up only marginally more protected against severe outcomes, and no one thinks the shots will banish COVID infections for good. There is, however, a simple rule of thumb that nearly everyone can follow to maximize the uncertain gains from a shot: Wait three to six months from your last COVID infection or vaccination.
Put that rule into action, and it plays out a little differently, depending on your circumstances.
If you haven’t had an Omicron infection:
If you haven’t had COVID since about November 2021, the advantage of a bivalent booster over the original formula is obvious, and as long as you haven’t gotten boosted recently, there’s every reason to get the new one right away. (If you have been boosted in the past few months, your antibody levels are probably still too high for a new shot to do much for you.) Marion Pepper, an immunologist at the University of Washington, told me that Americans who have already gotten three or more doses “have probably maxed out the protective capacity” of the original shots. By contrast, the bivalent vaccines offer something new to those who have so far escaped Omicron: a lesson on the spike proteins of the BA.4 and BA.5 subvariants, which will help the immune system fight the real thing should it get into your body. “I’m just super excited to get the bivalent vaccine,” says Jenna Guthmiller, an immunologist at the University of Colorado who has not yet had COVID. “I think it’ll be really nice and ease my mind a little bit.”
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If you have had an Omicron infection:
Veterans of Omicron infections might still have something to gain from seeing the BA.4 and BA.5 spike proteins—especially if your goal is to avoid getting sick with COVID at all. Past a certain number of shots, boosters’ impact on your long-term protection against severe disease is unclear, Goel told me. Paul Offit, the director of the Vaccine Education Center at Children’s Hospital of Philadelphia, told me he doesn’t plan on getting a booster at all this fall because, after three vaccine doses and an infection, “I think I’m protected against serious illness.” But if you want to stave off infection, Goel said, “the bivalent vaccines, or really any variant-containing vaccines, have real value.” That’s because formulas based on a given variant have been shown to temporarily increase your stock of antibodies that target that variant.
How long that extra-protective state lasts, or whether it’s sufficient to prevent any infection whatsoever, is still a scientific puzzle. The original boosters were shown to increase antibody levels to a peak about two weeks after the shot, then decay steadily over the following three months. We don’t know yet whether a bivalent formula will change that timeline, Goel said.
But you can still use it to estimate approximately when your protection will be at its highest. You might, for example, choose to err on the early side of that three-to-six-month timeline if you have a particularly high-risk event coming up in the next few weeks. “If all we had was the original booster and I was going to an indoor wedding or something, I think it would be reasonable to get that booster,” Pepper said.
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If you had an Omicron infection this summer:
“You’re still riding the wave of antibodies that you generated as a result of that infection,” Guthmiller told me, so a shot won’t do much for you yet. That’s true regardless of which Omicron subvariant you might have been infected with, she said, because BA.2 infections have been shown to protect fairly well against today’s dominant strains, BA.4 and BA.5. (BA.2 became dominant in the United States back in March.) The severity of your illness doesn’t really matter either, Goel said. A higher fever and more intense cough might indicate that your immune system got extra revved up, he said, but they could just as easily mean that your body needs more help responding to the coronavirus. In either case, once a little more time has passed, getting the bivalent vaccine could help extend your body’s memory of its last COVID encounter, and keep infection at bay.
If you’re at high risk:
Certain groups of people should get any booster as soon as it’s available to them, the experts I spoke with emphasized to me: immunocompromised people, people over the age of 50 or so, and people with medical conditions that put them at high risk of severe disease. If you fall in one of these categories and haven’t received all the boosters you’re eligible for, “I wouldn’t wait for the bivalent,” Offit said. For people in these high-risk categories who have already gotten the recommended number of boosters, you should get the new one as soon as it’s available to you. (The FDA and CDC have not yet indicated whether they will recommend a waiting period between your most recent shot and the bivalent booster.) Goel recommended waiting at least a month after your most recent infection or shot, but if you’re very worried about your risk, you don’t need to stretch the delay to three months. Your body might still have extra antibodies floating around, but with no practical way to check at scale, “I’m honestly in favor of recommending boosting as a way to maximize individual benefit,” he said.
[Read: America’s fall booster plan has a fatal paradox]
If you want to wait and see:
Waiting is always an option if you want to know more about how the bivalent vaccines perform. The FDA and CDC are set to green-light the shots based on human data from the existing boosters and other experimental bivalent boosters that didn’t make it to market in the U.S.—plus trials on the new formula in mice. Pfizer and Moderna simply haven’t progressed very far in their human trials. While there’s no reason to suspect that the new shots won’t be safe, Offit recommended opting for the original boosters until more safety and efficacy data are available, which could be as soon as a couple of months after the rollout—as long as the vaccine makers or the government collects that information and makes it public. But Guthmiller and Goel said they weren’t concerned about the lack of human data, and the bivalent shot is almost certainly the better bet.
There is one significant reason to avoid waiting too long for the bivalent shot: It offers the greatest protection against infection from the subvariants it’s actually designed around. BA.4 and BA.5 might be with us through the fall and winter—or they might give way to a different branch of Omicron, or even a variant that’s entirely unlike Omicron. You’d certainly be better off against this new variant with a bivalent booster than no booster at all. But if you want to maximize your anti-infection shield while you have it, consider putting it up against the enemy you know.