Don’t panic about unvaccinated kids It's time to get back to normal

Yet so far, Pfizer has failed to clear even this very low bar. Two doses of three micrograms of the Pfizer vaccine (1/10th the adult dose) fell short in December of 2020, to the disappointment of many. The FDA allowed the company to take another shot at it, literally, by adding a third dose. In late January of this year, there was buzz that the FDA would take the unprecedented step of authorising the vaccine despite the failed trial because it looked like it might reduce infections, but just a week later, Pfizer announced they would wait for the results of the 3rd dose before seeking approval. The flip-flop generated national news and outrage from some parents and doctors.

Then, on March 23, 2022, Moderna announced that its children’s vaccine — two doses of 25 micrograms, or 1/4 the adult dose — did generate sufficient antibody levels, again raising hopes that FDA approval would be forthcoming. But only limited results have been released so far. We don’t know the full spectrum of adverse effects, nor the impact on the outcomes we really care about: cases, severe disease, hospitalisations, MISC-C, and deaths. These outcomes are especially important for conducting a cost-benefit analysis for Moderna, which has clearly been linked to higher rates of myocarditis in young men than has the Pfizer vaccine.

As the clinical trials have dragged on, moreover, the landscape of kids and Covid has changed. Children have always been at relatively low risk, but newer variants appear to be even less risky for them. A recent preprint from the UK suggests that children infected with Omicron were less likely to be hospitalised with severe disease than children infected with the alpha or delta variants. We have also learned that MIS-C is less common often with the newer variants. Delta was less likely to trigger the condition than alpha, and CDC data suggests that omicron was less likely to trigger it than delta.

More generally, it makes no sense to be overly cautious about low-risk children at a time when the United States is dropping most restrictions for adults. The risk to an unvaccinated healthy child under five is often lower than the risk to their vaccinated or even boosted parent. Natural immunity is also powerful and prevalent. It protects strongly against reinfection and even hospitalisation after reinfection. Not that the data here is from adults — naturally immune children are so rarely hospitalised that it is difficult to conduct studies on them.

Most kids have already had Covid, even if they and their parents don’t know it. Prior to the omicron wave, up to half of American children had been infected, and the virologist Trevor Bedford estimates that omicron might have since infected 40% of Americans. Although there is surely some overlap between the two numbers, most kids have probably already had Covid at least once, and it would be difficult for a vaccine to offer them any significant further protection. Finally, we have learned that vaccination has rapidly waning protection against symptomatic infection. Some studies report that vaccine effectiveness in those aged 5-11 for symptomatic Covid is less than 20%.

If you put all this together, the story becomes clear. The vaccine trials have been inconclusive. Most children have had Covid already, and the ability for a vaccine to further improve their health is limited. Finally, they are at extremely low risk to begin with. Parents may encourage their offspring to get vaccinated if and when vaccines become available, but they should not be consumed with fear pending FDA approval. Nor should they prevent their children from living a normal life.

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Vinay Prasad is Associate Professor of Epidemiology and Biostatistics at the University of California, San Francisco. He is a practising hematologist and oncologist, and author of more than 300 peer-reviewed publications.

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