You’re Boosted! Now What?

No one knows exactly what the rules are for post-booster behavior.

masked people in a bus terminal
Mario Tama / Getty

Back in the winter, when the COVID-19 vaccines were fresh and his immune system was unenlightened, Mike Ford knew his marching orders: Don’t gather in crowds, or socialize unmasked; do stay at home, and get the jab when asked. Then came the end of March, and the first of his two Pfizer shots. Once vaccinated, Ford, a Ph.D. student studying historical musicology at Columbia University, began to ease up on masking, as the CDC told him he could; he started to hang out much more with others indoors, as the CDC told him he could. “I even took a short trip,” he told me. After a year or so of cloistering himself, he said, the changes felt bizarre, even “drastic.” But at least the rules were clear.

Now Ford, like so many others, has nabbed a booster, and he says the shot will, like his first two, “open up possibilities for me that I didn’t even consider before.” He’ll have his wedding, then a honeymoon, his post-nuptial schedule packed with travel and indoor socializing. He won’t worry about infecting his mom, who’s flying in from South Africa for the big day—a trip that, pre-booster, would have been “out of the question.” The shot’s still the catalyst for change, but this time Ford is the one making up the postinjection rules. In deciding what’s next, “I haven’t even thought about CDC guidance,” he said.

That’s not surprising, considering that specific guidance doesn’t exist. For months, the CDC has been updating its hefty page on what people can do once they’re fully vaccinated (which, by the way, is still defined as two weeks after the second Pfizer or Moderna dose, or two weeks after the one-and-done Johnson & Johnson). But no such instruction manual exists for the pre-to-post-boost transition, which some 120 million Americans will be eligible to make in the next few months. I asked the CDC if those recommendations might appear soon. “Not at this time,” Kristen Nordlund, an agency spokesperson, told me in an email. For now, “people who have received a booster should continue to follow CDC’s fully vaccinated guidance.” (Nordlund did clarify that people shouldn’t consider themselves boosted until two weeks post-jab. They just aren’t being told to, you know, behave any differently at that point.)

On a strictly scientific level, that conservative approach seems to check out with what a lot of experts are saying: “We’re still learning about what boosters mean, and what they can do,” Saskia Popescu, an infection-prevention expert at George Mason University, in Virginia, told me. She’s gotten a booster, she said, and hasn’t changed her behavior. But on another level—one that’s more emotional, more intuitive, and, let’s face it, more appealing—a different strain of booster logic holds: If two shots gave us so much freedom, shouldn’t a third do the same? Truly, no one knows. “Honestly, I’m confused on this myself,” Whitney Robinson, an epidemiologist at the University of North Carolina at Chapel Hill, told me.

Ford and others are now charting their own post-booster paths, freelancing in the advisory vacuum the government has left behind. Gerald Pao, a biologist, told me that nabbing a booster emboldened him to visit his elderly aunt in Vancouver. Dianne Jennings, in Boston, says that her booster has made her feel ready to take a delayed vacation to see family members in the Midwest, including an unvaccinated cousin. Ace Robinson, an infectious-disease expert in California, boosted his way into a trip to Egypt and a belated birthday party for his 95-year-old grandmother (also boosted). My own mother, who’s 71, told me that she feels like her Moderna booster is her ticket to traveling overseas; she’s also eager to dine indoors and spend more time with her unvaccinated great-nephew, who’s 8. She feels cooped up, she said over the phone: “It’s been too long.”

These booster mavericks aren’t acting unreasonably. (Nothing but respect, Mom.) In those with less robust immunity, additional shots do seem to make a difference, at least for a time: Once boosted, people seem better protected against infection and symptomatic cases of COVID-19, and they might be less likely to pass on the coronavirus. And while many people are eager to push their newly boosted boundaries, none of the dozen or so individuals I spoke with said they were abandoning other measures, including wearing masks. What they’re pursuing is well within the bounds for people whose bodies have been repeatedly taught to recognize the virus and have a great chance at fending it off. The whole pattern fits with a more general attitude toward behavioral taxes: taking precautions “so we can engage in something fun or rewarding,” like when we slather on sunscreen in advance of a beach party, says Gretchen Chapman, a behavioral scientist at Carnegie Mellon University who studies how people approach vaccines. That same calculus is part of what made the first vaccine rollout so appealing.

The benefits of vaccination, though, always work best on a community level—not as a personal super-shield. Popescu said she’s worried that some people will significantly overestimate the benefits of boosting; she’s already heard from at least one person who’s getting the shot so they can go back to clubbing. Frequent, heavy exposure to the virus can still overwhelm vaccines’ best defenses—no number of doses will ever rocket anyone up to “bulletproof protection.” But people might be more likely to behaviorally overshoot post-boost when they’re forced to intuit which activities are probably, likely safe, and shirk the ones that aren’t.

The last time we were at such a juncture, making the transition from unvaccinated to fully vaccinated, the calculations were simpler: We were all ending up in pretty similar, COVID-safe spots. Privileges were spelled out in intense detail on the CDC’s website; folks were told, point-blank, that they could “resume activities that you did prior to the pandemic.” This time around, though, the thinking’s much less binary—in part because boosters are being asked to play such different roles, depending on who’s getting them and when, Robinson pointed out.

For the immunocompromised, for instance, whose bodies have a tougher time responding to vaccines, additional doses are meant to generate protection that might have been mostly absent before; the CDC doesn’t even call these jabs “boosters” at all. The booster-made gains in protection can also be big for the oldest among us. This group started out at higher risk of getting severe COVID-19, and for them, post-vaccination protection against infection of all flavors seems to be on a bit of a decline. More shots can shore up those defenses—that’s what I’m hoping a booster will do for my mother, whose age and health conditions put her at high risk.

The younger, healthier contingent of the booster-eligible still seems pretty well guarded against COVID-19, but people in this group might work or live in places that up their chances of catching and transmitting the virus. Many experts think that members of this group really might not need additional shots at all, at least not yet: The benefits seem a bit unclear—like topping off a tank that’s already near-overflowing—and could be totally transient. For them, the boost is more like a hedge against the risks they’re already taking; it’s not intended to be an incentive to take on new ones.

The matrix that covers all of these scenarios is head-spinning, and no universal rule book can accommodate all of them. People’s risk budgets have also been different: Many never took advantage of all that being “fully vaccinated” allowed, and are finally starting to; others engaged in those behaviors, then dropped them during the summer of Delta, and now want to reclaim them. That’s a thorny landscape for any CDC guidance to wade into, especially when green-lighting activities for people who are boosted would also mean excluding many who are not and yet who remain, officially, fully vaccinated.

In one sense, boosters could be seen as helping level the playing field, adding protection where it was incomplete. Immune protection, once built, isn’t static; time and viral mutations do tend to erode it away. More shots for individuals can shuttle people back up the spectrum of defense. But that’s still just among the already vaccinated. The power of a booster still pales in comparison with that of a first shot. “It’s almost like we’re increasing the inequality in immunity,” Jennifer Dowd, an epidemiologist at Oxford University, told me. “Some now have supercharged immunity, some have none, and everywhere in between.” A best-case scenario is one in which more people are vaccinated, the virus doesn’t run as rampant, and we end up needing the shots less, not more.

In recent weeks, though, Americans have followed a nonideal pattern: Those seeking boosters have far oustripped those getting first shots—evidence of the persistent obsession over who needs more protection, rather than who has not yet gotten any at all. But even infinite boosters for the individual cannot compensate for a lack of vaccines for the community. “Our fates are inextricably linked,” Neil Lewis Jr., a behavioral scientist at Cornell University, told me. “It’s not just about how many doses I have in my body. It’s about how many doses the people around me have in their bodies.” The CDC likes to say that our health is up to each of us. But protection works best when we achieve it together.