Another FDA Blunder: How the Food and Drug Administration botched the vaccine-approval process for young children

A vaccine advisory meeting was scheduled for February 15, and many waited eagerly for dissemination of trial data, which were slated to be made public the Friday beforehand (February 11). On February 10, however, more leaked data emerged. The New York Times reported the sample size of the study, and that there were just 50 total infections, with a 57 percent reduction in cases. These data were sufficient for statisticians to estimate roughly the confidence interval, which was going to be very wide (anywhere from 25 percent to 75 percent), prompting more debate about whether it was prudent for the FDA to approve the shot.

Then, in a stunning about-face, Pfizer announced on February 11 that it was pulling its EUA from consideration. Gottlieb told reporters that there were too few cases, and too few symptomatic cases, in the trial. The numbers were unreliable, and the FDA and Pfizer would wait for the third-dose results to come in. Some observers were upset and argued that the vaccine should be made available, or that at least all data be made public—the latter an entirely reasonable request.

Few have grappled with the implications for this series of events, which represents an unforced error in vaccine regulation. First, the FDA vaccine division is operating at diminished capacity. Marion Gruber and Philip Krause, the director and deputy director of that division, famously resigned in the fall of 2021 after decade-long careers in response to pressure from the White House to approve boosters for all adults. As such, trust is already low in some quarters. Second, vaccine regulation is a reputational field. To an outside observer, it looks as if the agency does not know what it is doing. The agency has asked Pfizer to show that antibody levels are non-inferior—does it want this information or not? If the agency is happy with a reduction in Covid cases, it could have explicitly asked Pfizer to make this the primary endpoint of the study.

But it is unscientific to run a trial and then accept any endpoint that looks favorable. Scientists call it the Texas Sharpshooter fallacy: someone fires indiscriminately at the side of a barn and then paints a bullseye where several bullets happened to bunch together. The FDA appeared to be inviting such gaming.

Worse, just two weeks later, important data emerged suggesting that the vaccine was much less effective at blocking infection in the older, five- to 11-year-old age group. Investigators speculate that one potential reason was the lower dose. But if the dose is responsible for the inferior performance in five- to 11-year-olds, what would have happened had authorities authorized an even lower dose in those aged six months to four years?