COVID-19 vaccination reduced the likelihood of MIS-C in children ages 12–18 years by 91%. Data from July to December 2021 show that 95% of children ages 12 through 18 years hospitalized with MIS-C were not vaccinated. CDC is collecting data on how well COVID-19 vaccination works against MIS-C in younger children. As more children under 12 years old get vaccinated, CDC will be able to analyze and share those data.