The CDC’s guidance is confusing, but the best rationale for boosters for healthy younger workers is that the shots will help prevent viral spread. Such workers are unlikely to get seriously ill.

Steven Senne / AP, File

As an infectious-disease doctor in my 30s treating immunocompromised patients, I recently decided to get the booster dose of the Pfizer-BioNTech coronavirus vaccine. I did so knowing that research shows my first two doses are still working exceptionally well to protect me from severe disease. Still, some of the patients I am caring for cannot mount an immune response even to the first two doses of the vaccines. That puts them at higher risk of contracting and possibly even dying from the virus, and I will do everything in my power not to infect these vulnerable patients.

It was controversial when the director of the Centers for Disease Control and Prevention, Rochelle Walensky, overruled a recommendation by an advisory panel last month on who should receive booster doses of the Pfizer vaccine. The panel had recommended boosters for people 65 and older and for younger people with certain underlying conditions. Walensky went further and concluded that workers with high risk of occupational exposure may be vaccinated on request with a booster dose – including teachers, health-care workers, grocery clerks, food and agricultural laborers, public transit workers and day-care workers. (Similar recommendations about booster shots appear to be on the way for the other vaccines – although everyone who got a Johnson & Johnson shot may be eligible. And the Food and Drug Administration is moving toward letting Americans switch vaccines when they get a booster.)

A case can be made that booster shots are warranted for people in the occupational-risk categories, but it is not because these workers are at a particularly high risk of getting very sick. It is because they are at higher risk of spreading the virus to those who cannot protect themselves. That category includes immunocompromised people (like my patients), kids who are not yet eligible for their first doses, very elderly patients with multiple medical conditions and even, to a lesser degree, people who have chosen to not get vaccinated. (I say “lesser degree” because there is obviously a more effective and direct way those people can protect themselves: They can get the jab.) The defensible case for boosters for young, healthy workers such as myself has almost entirely to do with preventing us from becoming intermediate hosts of the virus – even if that’s not how the decision has been presented.

Our data shows that coronavirus vaccines (particularly the mRNA-based vaccines) offer ongoing robust protection against severe disease or hospitalization, even months after the primary series of doses. However, we have consistently seen that vaccine effectiveness is waning against infections in all age groups; that means more vaccinated people are contracting the SARS-CoV-2 virus than before, even if they aren’t developing covid-19.

Data from Israel has played an important role in persuading people, including government regulators, that boosters help. Initial data from that country suggested that boosters prevented both infections and severe disease, to a meaningful degree, among those 60 or older. More recent data from Israel also shows slightly less incidence of severe covid-19 in 40- to 59-year-olds, after they got booster shots – but the risk goes from tiny to minuscule. In those under age 40, there were too few cases of severe disease to meaningfully compare the booster and non-booster groups.

On its website, the CDC doesn’t distinguish between giving boosters to protect the health of front-line workers versus giving them boosters to protect people they may come in contact with. In fact, the CDC suggests front-line workers may want boosters for the same reason the elderly will get them: “Emerging evidence . . . shows that among healthcare and other frontline workers, vaccine effectiveness against COVID-19 infections is decreasing over time.” But infections and clinical disease are different in important ways: Infection will continue, given that the coronavirus will not be completely eradicated; we can and must control serious disease.

The CDC’s failure to make that crucial distinction has potential social, political and ethical costs. First, anti-vaccine groups may argue that boosters for the healthy are an indication that vaccines don’t work. The CDC already rebuts this point on its website. But if the CDC were to explain that we want to protect people who aren’t at risk of serious disease from becoming carriers, the true meaning of “fading efficacy” for younger people would be clearer.

Second, we know that vaccines, while exceptionally safe, do have risks, particularly in certain groups. For J&J doses, the risks include increased brain clots in women under age 50. And mRNA vaccines have been linked to myocarditis (heart inflammation) in younger men. Young, healthy workers should have the chance to weigh risks and benefits in the proper context. They should be told that boosters, as of now, will provide a secondary benefit (to other people) more than a primary one (for them). People may well still decide to get the dose, as I did, but they will have the right facts at hand.

The CDC’s lack of clarity on this question can also erode trust in the agency: Imagine that someone suffers a rare vaccine side effect and concludes, upon examining the evidence, that they were exposed to this risk not to help themselves but to protect other people. They may feel misled.

In the end, boosters – though important in some work settings, like hospital wards – are not an especially efficient way to stop the spread of the virus in the general public. It’s far more effective, given a choice, to vaccinate people who have never been vaccinated in the first place – a group that still constitutes about a fifth of American adults. But the rate of unvaccinated people seeking vaccination has slowed to a crawl, whereas many vaccinated people are eager for boosters. Preventing spread via boosters is therefore a worthwhile, achievable goal. (The logic of using boosters to prevent spread could also be invoked by parents of unvaccinated children and people with immunocompromised family members – so we can expect the calls for broader booster authorization to continue.) It is especially particularly important to reduce spread now because we have new antiviral therapeutics and long-acting monoclonal antibody prophylactics on the horizon that could help our most vulnerable patients.

The decision to let high-exposure workers get boosters may assuage some workers’ anxiety about perceived risk and could help prevent workers from testing positive and missing workdays – but our vaccines were already achieving the goal they were designed for: turning SARS-CoV-2 into a far less deadly virus for the general population. While that may not hold true indefinitely, it does right now.

If you’re a front-line worker, should you get a booster shot to reduce the risk of people you may come in contact with? Different people, in different workplaces, will come to different conclusions. But at least that’s the right question.

Abraar Karan is an infectious disease physician at Stanford University. He previously worked on the Massachusetts state covid-19 response as a medical fellow to the state public health commissioner, and on the World Health Organization’s Independent Panel on Pandemic Preparedness and Response.

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