Fully Vaccinated Is Suddenly a Much Less Useful Phrase

With tens of millions of Americans eligible for booster shots, the term could start to lose its meaning.

Two multicolored syringes and one white syringe
Shannon Lin / The Atlantic

The definition of full vaccination against COVID-19 has, since the winter, been somewhat difficult to nail down. It takes one dose of Johnson & Johnson, but two doses of an mRNA vaccine. The CDC counts you as fully vaccinated as soon as you get your last shot, but tells you that you won’t be fully vaccinated until two weeks after that. People have a hard time knowing exactly when it might be safe for them to venture into restaurants, wedding venues, or mask-free offices.

Now, in the age of booster shots and breakthrough cases, the phrase has gotten even murkier. Early this morning, the CDC officially backed booster shots for tens of millions of Americans who are six months past their second Pfizer dose: those over 65, those in long-term-care facilities, and all adults who have an underlying medical condition that puts them at high risk of severe COVID-19 or who are at high risk of getting sick from occupational or institutional exposure to the coronavirus.

During a two-day meeting of the CDC’s Advisory Committee on Immunization Practices this week, the CDC’s Sara Oliver advised the committee that the agency’s definition of fully vaccinated would not change—at least for now. That makes it much less useful as a category: Will some fully vaccinated people be more vaccinated than others? And it leaves open the possibility that the definition could change as more information becomes available: If you’re fully vaccinated now, could you become un-fully vaccinated a few months down the line? These questions go beyond semantics. As more and more Americans are mandated to be “fully vaccinated” in order to work—see here, here, and here, for example—continued clarity on what that category means, and who belongs in it, will be crucial.

Fully vaccinated didn’t originate with the coronavirus. The term has been used for other vaccine series that require multiple shots, such as those for measles, hepatitis B, and HPV. Currently, the CDC considers people to have achieved full vaccination against COVID-19 “2 weeks after their second dose in a 2-dose series, such as the Pfizer or Moderna vaccines, or 2 weeks after a single-dose vaccine, such as Johnson & Johnson’s Janssen vaccine.” The agency’s website does include a caveat: For the immunocompromised, being fully vaccinated might not be the same as being fully protected, so a third shot is a good idea.

Part of the problem is that the difference between full vaccination and full protection has been explained less than perfectly to the American public. The truth is, no one is 100 percent protected from the coronavirus after vaccination, regardless of how healthy their immune system is; that’s simply not how vaccines work, especially in the context of a pandemic virus that hasn’t stopped evolving. “You cannot definitively say, until we have finally beat the virus or gotten it to a point where it is no longer killing people, that you are [fully] protected,” says Ruqaiijah Yearby, a health-law expert and co-founder of Saint Louis University’s Institute for Healing Justice and Equity.

Even before booster shots were a mainstream possibility, the concept of full vaccination could lead people to develop what Saskia Popescu, an infectious-disease epidemiologist at George Mason University, calls a “Superman complex.” After getting their J&J shot or their second mRNA dose, some people feel immediately invincible, she told me, as though nothing they do is dangerous to themselves or the people around them. The ongoing discussion about boosters could be an opportunity to undo the Superman complex by adding some nuance, reminding the public that no vaccine is perfect and that we all must work together to get the pandemic under control. Such a rethinking could even go beyond COVID vaccines. “Maybe we need to reimagine how we communicate vaccines in general,” Popescu said.

A sudden injection of nuance could confuse a lot of people, though, and even discourage some from getting their first shot by making the process seem especially convoluted or onerous. For schools, businesses, and other institutions that have implemented vaccine requirements over the past few months, it would likely be a nightmare. If getting two shots doesn’t guarantee that you’re fully vaccinated, then who should be allowed to come to work? Will schools need to interview every teacher who was vaccinated before April about their medical history?

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Now that the CDC has recommended that a select swath of the population gets a third dose to help keep them from getting sick and spreading the virus, institutions that require full vaccination will be faced with some difficult choices. Should they demand that immunocompromised 40-year-olds get a third shot, while asking nothing more of 40-year-olds with healthy immune systems? Should they require proof of booster shots from only those who got the Pfizer vaccine, because they’re the only ones for whom boosters have been authorized so far? Or would it make more sense for companies to stick with the definition of fully vaccinated that they’ve been using to this point?

Seema Mohapatra, a visiting law professor at Southern Methodist University, told me that setting up different rules for different people probably would not create legal liabilities for the mandating party, but it could lead to “practical, administrative problems.” Restaurants and theaters, for example, have no way of verifying their patrons’ health status, so they can’t know who is in a booster-eligible category. HR departments would be hard-pressed to track which vaccine Carol from accounting received, how long it’s been since her last dose, and how that lines up with her 65th birthday.

There are also ethical problems to consider: Even if it’s legal, is it really fair to ask essential workers and immunocompromised people to get more doses than others in order to make a living, or even just to go out to eat? Given that plenty of underserved communities still have trouble accessing the shots, asking even more of the most vulnerable among us—without accompanying policies to bring them shots where they live and work, guarantee them paid time off, and offer them hazard pay—would be hard to justify.

The problem isn’t just with updates that affect different people differently, but also with constant, complicated shifts in policy, according to Jason Schwartz, a vaccine-policy expert at the Yale School of Public Health. If employers and schools update their mandates with every incremental change to the CDC’s recommendations, he told me, their tweaks could backfire and discourage vaccination. It would be better to wait for the CDC to recommend universal boosters, and then update the rules for everyone at the same time.

On the national level, mandates probably won’t change much in the immediate future. Anthony Fauci, the director of the National Institute of Allergy and Infectious Disease and Joe Biden’s chief medical adviser, told The Atlantic this week that for at least the next few weeks, “any vaccine mandates would have to go with the original vaccine regimen.” Paul Offit, who directs the Vaccine Education Center at the Children’s Hospital of Philadelphia and serves on the FDA advisory committee that recommended authorizing third Pfizer doses for a select group last week, told me that as far as a three-dose mandate goes, “I just don’t think it’s right now.”

Continued clarity over who counts as fully vaccinated wouldn’t just help employers set rules. It would also give researchers more precise language with which to investigate breakthrough infections and vaccine efficacy. Popescu pointed out that a reworked definition of fully vaccinated could allow for multiple definitions of partially vaccinated too. Are those who haven’t gotten their second mRNA dose really in the same category as those who got their second shot more than six months ago but haven’t yet gotten a booster? Should a breakthrough infection in the first group be given the same weight as one in the second, for the purposes of assessing how well the shots are working or who can safely be invited to your dinner party?

One common critique of the push for boosters is that it has no limits, that we may end up needing a fourth booster, or a fifth, or a shot every six months for the rest of our lives. “I do think that the endgame in a year or two will likely be a vaccination program that regularly updates the vaccine and is administered on a set schedule for everyone,” Schwartz said. COVID shots might even be combined with annual flu shots.

If that’s what happens, employers and schools will have new choices to make about mandates, such as whether to require shots for their employees every year and whether to provide those shots on-site. The longer we live with endemic COVID, and the more normal and predictable boosters become, the easier these conversations will be.

Katherine J. Wu contributed reporting.