As news of Moderna’s new wonder vaccine to prevent COVID-19 in young children flashes across the media today, a vital piece of information is missing in the Cambridge, Massachusetts pharmaceutical company’s media release. Moderna’s interim analysis of vaccine efficacy, the relative risk reduction (RRR) in the Phase 3 KidCOVE study of its COVID-19 vaccine for children six months to two years, and two years to six years is 43.7% and 37.5%, respectively. Moderna Announces its COVID-19 Vaccine Phase 2/3 Study in Children. Not surprisingly, Moderna’s report doesn’t mention the more clinically meaningful absolute risk reduction (ARR) of the vaccine, which is the mathematical difference between the infection rates in the vaccine and placebo groups of the clinical trial.

Usually, the absolute risk reduction is easily calculated from reported clinical trial data. But Moderna appears to have carefully omitted reporting any of the clinical trial data in its interim analysis that would enable one to calculate the absolute risk reduction. That is, Moderna’s report doesn’t list the specific number of children who were infected in the vaccine and placebo groups—the percentage of infected children per group.

Subtracting the percentage of infected children in the vaccine group from the percentage of infected children in the placebo group equals the absolute risk reduction. But without disclosing the baseline risk (the risk in the placebo group), it’s impossible to calculate the absolute risk reduction and the number needed to vaccinate to prevent one infection.

Why is Reporting the ARR Important?

Moderna has a history of reporting a vaccine efficacy of approximately 95% for its mRNA COVID-19 vaccine for adults, when the reality is that the vaccine’s absolute risk reduction is only 1.1%. Outcome Reporting Bias in COVID-19 mRNA Vaccine Clinical Trials. This should warn parents and guardians to expect that the ARR could be much lower than the reported RRR in Moderna’s latest version of the vaccine for young children.

Moderna’s report concludes, “We believe these latest results from the KidCOVE study are good news for parents of children under 6 years of age.”

In my opinion, no parent or guardian of young children should trust Moderna’s interim report on its vaccine for young kids!