Multisystem Inflammatory Syndrome in an Adolescent Following SARS-CoV-2 Exposure Despite Three Doses of a COVID-19 Vaccine.

The multisystem inflammatory syndrome in children (MIS-C) is a known complication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in the pediatric population. Recent studies have demonstrated high efficacy of a two-dose vaccine series in preventing MIS-C among adolescents. To date, such studies have only included children exposed to SARS-CoV-2 prior to the emergence of the Omicron variant (B.1.1.529). We report a case of an adolescent who received three doses of a vaccine yet developed MIS-C following known exposure to SARS-CoV-2. Given the uncertainty in whether current vaccines offer as much protection against MIS-C due to the Omicron variant or any potential new variants as they have for older variants, pediatric providers should maintain a high index of suspicion for MIS-C regardless of vaccination status.