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

Abstract

Multisystem inflammatory syndrome in children (MIS-C) is a complication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection; in the United States, reporting of MIS-C after coronavirus disease 2019 (COVID-19) vaccination is required for vaccine safety monitoring. Pfizer-BioNTech COVID-19 vaccine was authorized for children aged 5-11 years on 29 October 2021. Covering a period when approximately 7 million children received vaccine, surveillance for MIS-C ≤ 90 days postvaccination using passive systems identified 58 children with MIS-C and laboratory evidence of past/recent SARS-CoV-2 infection, and 4 without evidence. During a period with extensive SARS-CoV-2 circulation, MIS-C illness in children after COVID-19 vaccination who lacked evidence of SARS-CoV-2 infection was rare (<1 per million vaccinated children).

Keywords: COVID-19; COVID-19 vaccine; MIS-C; SARS-CoV-2; multisystem inflammatory syndrome in children.

Figure 1.

Investigation of potential MIS-C in children who had received COVID-19 vaccine. Abbreviations: CDC, US Centers for Disease Control and Prevention; CISA, Clinical Immunization Safety Assessment Project; IVIG, intravenous immunoglobulin; MIS-C, multisystem inflammatory syndrome in children; NAAT/Ag, SARS-CoV-2 nucleic acid amplification test or antigen test; VAERS, Vaccine Adverse Event Reporting System. ^aVAERS report indicated the child was not hospitalized and there was no clinical suspicion of possible MIS-C. ^bIn 2 instances, the VAERS report was incomplete and patient information needed to request medical records was not provided; there was no information on SARS-CoV-2 testing. In 7 instances, a report was made to CDC’s MIS-C surveillance unit but not to VAERS and medical records were not available. Four of 7 were described to be NAAT/Ag positive in the past or during MIS-C evaluation, the 3 others were described to be NAAT negative/serology positive with no further details on testing. ^cAlternative diagnoses: adenovirus infection (n = 2), murine typhus (n = 2), and 1 each of monoarticular arthritis, pericarditis, adrenal insufficiency. ^dOne child who tested NAAT positive at admission died; the cause of death as assessed by the state medical examiner was MIS-C associated with COVID-19. This child was included as meeting clinical and inflammatory criteria and without alternative diagnosis based on that information. ^eWe used only positive serology results from specimens collected before any IVIG receipt (positive serology results from only post-IVIG specimens are considered as “test not performed”). ^fHistory of positive NAAT/Ag test in the past, or positive NAAT/Ag test during the MIS-C illness evaluation, or positive anti-nucleocapsid antibody test during the evaluation. ^gNo history of positive NAAT/Ag test in the past, negative NAAT/Ag test during the MIS-C illness evaluation, and negative anti-nucleocapsid antibody test during the evaluation. ^hNo history of positive NAAT/Ag test in the past, negative NAAT/Ag test during the MIS-C illness evaluation, and anti-nucleocapsid antibody test not performed. ^jAn anti-spike antibody test was obtained in only 1 of the 4 children in the box above, and the result was positive.