New Guidance on Booster Shots Gets Ahead of the Science

There’s finally a decision on which Americans should get booster shots against Covid-19. Unfortunately, some of the new federal recommendations go well beyond the data and foist the decision of appropriateness onto individuals and their doctors. And by expanding booster eligibility to a huge swath of the population, the Biden administration risks undermining confidence in vaccines.

The reality is that available vaccines continue to protect almost everyone against severe illness. That means there’s still time to gather more data on the benefit of boosters for people who are not high-risk and, in the meantime, focus on decreasing the number of unvaccinated Americans, where a crisis remains.

On Friday, the Centers for Disease Control and Prevention recommended that among people who received two Pfizer-BioNTech vaccine shots over six months ago, two groups should get boosters: All people 65 or older and people 50 to 64 with underlying medical conditions. But the C.D.C. also said two additional groups “may” get boosters “based on their individual benefits and risks”: people 18 to 49 with underlying medical conditions and people 18 to 64 who are at a high risk of coronavirus exposure at work.

The second set of recommendations is premature and too vague. Here’s why.

Data from Israel, Britain and the United States show that the available Covid-19 vaccines continue to provide excellent protection against hospitalization and death for almost everyone. Exceptions include the immune-compromised (who were already authorized to get a third dose) and people age 65 and older. These two groups are at the highest risk of serious illness from infection, even if they are vaccinated.

But there is inadequate evidence to support boosters for the general, younger population, including most people with underlying medical conditions. The C.D.C.’s list of conditions that make someone eligible for a booster is remarkably long, and few if any of these conditions have been shown to carry any additional risk of severe breakthrough illness. Boosters might help some people on the list, but the overall impact is likely to be small. Many thousands of young people would need to get additional shots to prevent a single hospitalization.

There’s also inadequate data on the safety of third doses. The C.D.C. was honest about that. The advisory committee for the agency said it was unsure how many cases of the heart-inflammation condition myocarditis — the most common serious adverse event in young adults — a third dose might cause. Although the number is unlikely to be high, it’s not clear whether the number of young people who might be helped by a booster is greater than the number who might be hurt. The C.D.C.’s committee presented data on this that was inconclusive, and ran models that were openly based on guesses. We appreciated their transparency on that.

But the second set of recommendations ignore that uncertainty in favor of high-stakes epidemiologic gambling. If more people may be harmed than helped by boosters, that’s a nonstarter for any health intervention. In addition, people still on the fence over getting vaccinated at all may be discouraged by the notion of needing a third dose (data show that around one-third of Covid-vaccine-hesitant people say they would be dissuaded).

People getting a booster now may also risk the possibility of forfeiting something better tomorrow. Coming just around the corner are data on half-dose Moderna boosters, for example. We anticipate new data on the benefits of “mix and match” boosters, in which someone who received one kind of vaccine receives a different type as a booster. Preliminary data from Britain suggest that this strategy may prove to be the most powerful type of booster. If the United States rushes today, the country might find itself with fewer options later.

Many people will reach out to their doctors for guidance on whether they should get a booster. We believe in the value of the physician-patient relationship. The concept of “shared decision-making” between doctor and patients has been a wonderful innovation in the last decade or more. But the C.D.C. guidance does little more than transfer uncertainty from public health experts to an overburdened health care work force.

This puts providers in an unusual situation. How can physicians like us advise patients when we don’t know the answers to crucial questions like: Is a booster safe for me? Will it help me? As emergency physicians and public health professionals, we are frequently asked, “What would you do?” In the case of boosters, neither of us feels there’s sufficient information to make informed choices for ourselvesor our families, let alone for everyone else.

Leaving booster decisions in the hands of individuals and their doctors will also worsen existing vaccine inequities. Low-income and minority populations — which have had the most trouble getting first doses — are also the least likely to have a primary care doctor. Additionally, substantially increasing boosters for Americans will strain attempts to increase vaccine access across the globe.

The most important thing the United States can do to avoid severe disease, hospitalization, death and long Covid is to reduce the spread of the coronavirus. By far the most effective way to do that is not through boosters for people who may not benefit, but by getting unvaccinated people vaccinated.

As President Biden said Friday, millions of eligible Americans remain unvaccinated. The nation’s resources should focus on first shots, rather than on dubiously effective boosters. That effort should supersede all else.

Megan L. Ranney (@meganranney) is an emergency physician and associate dean at the School of Public Health at Brown University. Jeremy Samuel Faust (@jeremyfaust) is an attending physician at Brigham and Women’s Hospital Department of Emergency Medicine in Boston and an instructor at Harvard Medical School.

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