The FDA’s vaccine regulation is sliding further into the abyss. Last week, Pfizer announced that it would seek emergency-use authorization for a fourth dose of its mRNA vaccine, based on the original Wuhan strain of Covid-19, in people over 65. Meantime, Moderna announced that it was seeking an even larger market share: a fourth dose in anyone over 18, based on its original mRNA vaccine. If the FDA moves forward on authorizing either product, it will cement a dangerous precedent: inadequate evidence being used to justify widespread vaccination for years to come.

More than 255 million Americans have received at least one dose of the vaccines, 217 million have completed a full course, and 76 million have been boosted, earning Pfizer and Moderna billions of dollars in the process. At least 140 million Americans have had Covid-19. Many have experienced both vaccination and breakthrough infection. Several sources suggest that vaccination remains highly effective against hospitalization and death, while the ability of several vaccines to prevent mild infections has plummeted. This means that it is highly unlikely that additional boosters would block mild infections beyond a few months, or further lower the risk of severe outcomes in an otherwise healthy person who has received two or three doses and possibly had Covid-19 as well.

Further, the FDA is not operating at full capacity when it comes to vaccine regulation. The agency’s director and deputy director of vaccine products resigned last fall, citing White House pressure to approve third doses for all adults and writing damning op-eds critical of the FDA’s subsequent decision to do so. Notably, one vaccine expert, Paul Offit, has advised his own 20-year-old son not to receive a third dose because he was not convinced that it provides a net benefit at that age. These arguments apply even more forcefully to fourth doses and beyond. Medicine, like many other fields, is subject to the law of diminishing returns. It’s increasingly difficult to reduce the risk of bad outcomes for healthy, boosted 20-year-olds (who may also have been infected with Omicron) because their risk is already so vanishingly low.

If the FDA authorizes a fourth dose, we can expect the vaccine mandates to follow soon thereafter. Several institutions have already mandated third doses even in ultra-low-risk populations. Colleges around the country have instituted booster mandates for students. Princeton has refused to exempt healthy students with two doses and a prior infection from its booster mandate. The University of California’s booster policy also applies to the UCLA laboratory school (a high school), mandating a third dose for students aged 12 and up. There is little reason to doubt that institutions like these would quickly mandate a fourth dose.

The data supporting fourth doses aren’t up to medicine’s gold standard: a randomized trial. Instead, we have two observational studies comparing people who rushed to be boosted with those who didn’t. Of course, these two groups comprise fundamentally different sorts of people, as we can see in one of the studies, which appeared to show a large beneficial effect on the first day after subjects received a fourth dose. It’s impossible for a vaccine to work in a single day, so the difference must be due to bias, thus calling into question later estimates as well. The other study, which looked at health-care workers in Israel and relied on actively testing people with no symptoms, found a reduction in infections (30 percent)—a result that, again, the non-randomized nature of the study calls into question. (As even that study’s authors conceded, “Most infected health care workers reported negligible symptoms.”)

No matter how many doses the FDA approves, vaccination will never halt transmission. We will all eventually get a breakthrough infection. Ideally, we should meet the virus on the best of terms, having addressed underlying health problems and received primary vaccination.

The Biden administration’s vaccine policy has fared poorly in this regard. The U.S. has a lower rate of vaccination than Iran, Cambodia, Colombia, El Salvador, Brazil, Peru, Canada, the European Union, the U.K., Australia, New Zealand, South Korea, and Japan. The FDA unnecessarily got parents excited about vaccinating kids aged six months to four years, based on unreliable data, then pulled the plug on authorization. Now, using more flawed data, it’s poised to cement a regulatory precedent that could lead to annual or biannual boosters. Pfizer and Moderna will get rich, our arms will ache, and no one will know if we made the right decision.

Photo by Pasquale Gargano/Pacific Press/LightRocket via Getty Images


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