New Pfizer Study the Media is Not Covering: 3-Doses of Covid Vax for Kids Under 5 Had No Significant Benefit

Unfavorable results from a new Pfizer study have been ignored by the media, and cleverly spun as a positive by study authors.

A few days ago I published a critical piece about the US’s blanket recommendation for everyone aged 6 months and up to get the new Covid vaccine. The policy was met with swift backlash from a number of public health professionals, and it differs greatly from the tailored vaccine policies in many other countries. The study that I discuss below, which was published right after the CDC’s recommendation, makes for a fitting sequel.

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On Friday September 15, the Journal of the American Medical Association published a study that calls into the question the CDC’s vaccine policy for children under aged 5. The study analyzed the effectiveness of the Pfizer vaccine on preventing Covid-related medical visits for children aged 6 months through 4 years old.

Its findings are particularly noteworthy because the study was conducted by Pfizer itself, along with researchers at Kaiser Permanente. And because, despite the vaccine already being approved and recommended for babies and toddlers, until the study’s publication there were no analyses on the vaccine’s effectiveness for preventing outcomes that led to medical attention for this age group.

The vaccine for this age group was designed to be given as a three-dose primary series, which is the schedule that the FDA authorized and that the CDC recommended. While the study showed a benefit of two doses at reducing the likelihood of Covid-related emergency department, urgent care or outpatient visits, it found no statistically significant benefit for children who received the recommended three doses versus unvaccinated children. In other words, the vaccine taken as directed did not reduce the incidence of emergency room or medical office visits related to Covid for this age group.

Image from the Pfizer study in JAMA.

In the Figure above note that the “3-dose” bars, those with the blue dots in the center, extend above the dotted horizontal line at 1.0. This means that the range of estimates for expected outcomes—what’s known as the confidence interval—includes three doses being worse than no vaccination at all.

The authors theorize that the reduction in effectiveness of 3 doses “is likely due to more immune-evasive Omicron sublineages becoming dominant by the time young children received their third dose and longer median time since dose 3 compared with dose 2.” This very well may be true—we don’t know. Or the reduction in protection with the third dose could be due to immune imprinting, or, as an infectious diseases physician I spoke with suggested, it could due to confounding (uncontrolled variables), such as kids who get three doses might in some ways differ from kids who don’t get vaccinated. Maybe the type of children who got three doses test more often or are more likely to seek care. Whatever the explanation, it’s conjecture. The point is, regardless of the reason, Pfizer’s own study shows that if children received the vaccine as directed it did not yield a conclusive benefit against preventing illness that led to medical care.

One might think this finding would make for important news. The approval of the vaccine for this youngest age group, in June 2022, was trumpeted with much fanfare. And beyond being the official recommendation from the CDC, a long list of influential private medical organizations, like the American Academy of Pediatrics, applauded the approval.

Yet close to zero major media outlets have covered these findings. Of the few outlets that did cover the study, they instead reported that the results show the vaccine was a big success. A Yahoo! News headline, for example, declared, “New study confirms effectiveness of COVID vaccines for kids under age 5: 'It helps keep children out of the emergency room.’”

Yahoo! News, and the doctors quoted in its article, made this claim because that is how the authors framed the results.

Even though the vaccine was designed to be given as a three-dose primary series, and that is how is was approved and recommended, the authors created a category of merged results from children who had two doses or three doses. The combined category squeaks by to show a benefit.

Among other limitations, because this is an observational study, there is the possibility of confounding, making its results—good, bad, or otherwise—potentially unreliable. But taken at face value, and considering there are no other data, and that this study is from Pfizer, the findings are newsworthy and noteworthy.

Given the US’s outlier status on its new recommendation for everyone—including healthy children all the way down to six months old—to get the latest Covid shot, and the lack of evidence for its benefit for all groups to prevent severe disease, the results from this study on the primary series are worth keeping in mind when considering the wisdom behind the CDC’s new recommendation.

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