Surveillance for Multisystem Inflammatory Syndrome in US Children Aged 5–11 Years Who Received Pfizer-BioNTech COVID-19 Vaccine, November 2021 through March 2022.

This article focuses on surveillance of multisystem inflammatory syndrome in children (MIS-C), a serious hyperinflammatory condition associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, occurring after Pfizer-BioNTech COVID-19 vaccination in U.S. children aged 5–11 years. Among approximately 7.3 million vaccinated children during November 2021 to March 2022, 69 cases met clinical and inflammatory criteria for MIS-C without alternative diagnoses; 58 had laboratory evidence of past or recent SARS-CoV-2 infection, while 4 had no such evidence. The findings indicate that MIS-C without evidence of SARS-CoV-2 infection following vaccination was rare, with a reporting rate of less than one case per million vaccinated children, though the study could not determine causality between vaccination and MIS-C. Surveillance relied on passive reporting systems and included cases overlapping with Kawasaki disease due to diagnostic challenges, during a period of widespread SARS-CoV-2 circulation.