A vaccine dose.

When Pfizer CEO Albert Bourla said on March 13 that all Americans would need a second booster shot, it struck many covid experts as a self-serving remark without scientific merit. It also set off spasms of doubt over the country’s objectives in its fight against the coronavirus.

The decision on how often and widely to vaccinate against covid-19 is part science, part policy, and part politics. Ultimately it depends on the goals of vaccination at a time when it’s becoming clear that neither vaccines nor other measures can entirely stop the viral spread.

On March 15, Pfizer made a more limited request of the FDA, seeking authorization of a second booster only for people 65 and older. Advisers for the FDA and the Centers for Disease Control and Prevention are likely to approve a fourth shot for people in that age group because they’re the group most likely to be hospitalized or die of covid.

The vaccines’ protection against covid infection generally wanes within several months in all age groups. But experts disagree on whether frequent boosters, especially for younger people, can do anything about that.

Throughout the pandemic, repeated public proclamations by pharmaceutical company executives — broadcast widely via the media, often without supporting data — have created pressure for politicians and their scientific advisers to act.

Although FDA and CDC expert panels, and some federal scientists, were hesitant about recommending the first booster for younger populations, the agencies overrode their advice and approved boosters for everyone 12 and older. That continues to be a sore point with many immunologists and infectious disease specialists.

The desire to react to growing signs of infection is understandable but may be futile in the face of a virus that seems to infect even the well-vaccinated. If we keep chasing the virus with boosters, “we’re going to be making the drug companies very happy, since our antibodies will go down every four months,” said Dr. Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia. Offit cautions against leaning too hard on COVID boosters for answers. 

But whether those levels are a good measure of protection — especially against serious disease, and in which populations — is an open question. The answer is important because, like all vaccines, there is a small risk of adverse reactions from each shot.

There is some disagreement among experts on how well covid vaccines to date have prevented serious disease in healthy young people, and whether and how often they should be boosted.

While a recent CDC study showed an increased risk of hospitalization among people ages 18 to 49 several months after second and third vaccine doses, the data categories in the study aren’t fine-grained enough to show whether many of those who suffered severe disease had comorbidities such as chronic disease or obesity, Offit said.

But others argue there’s enough evidence to show that yearly vaccines, perhaps in combination with influenza vaccinations, would be the best solution. 

“Given how safe the vaccines are and how effective they are, I think it probably does make sense for people to get a booster, and the most convenient would be once a year,” said Dr. Otto Yang, an infectious disease specialist at UCLA. If covid turns out to be seasonal, peaking in winter months, vaccination in the fall would provide decent protection, he said.

It’s important for U.S. health officials to have and share with the public some clarity about the goals of the vaccination program, said Dr. Luciana Borio, a senior fellow for global health at the Council on Foreign Relations. 

“We need people to understand that protection against all illness is not long-lasting, instead of thinking the vaccine is not working,” she said.

“The goal is not to stop transmission, it’s mainly to protect the vulnerable at this point,” said Dr. Norman Hearst, a family physician and public health researcher at UC-San Francisco.

How, in the absence of perfect vaccines, we will protect the vulnerable remains a conundrum. Borio argues that we need systems to rapidly test elderly and immunocompromised people for covid and quickly give them treatment if their results are positive.

For the time being, all debate on a second booster is moot, said John Wherry, chair of the Department of Systems Pharmacology and Translational Therapeutics at the University of Pennsylvania. Unless Congress reverses itself and decides to give the administration more money to fight covid, there won’t be any free vaccines — or free covid treatments — available to the public next fall.

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