Key Points

• Between March 2, 2020, and February 20, 2022, 1,022 cases of pediatric multisystem inflammatory syndrome (PIMS or MIS-C) were reported to Santé publique France, including 938 linked to COVID-19. Following the intense circulation of SARS-CoV-2 since late October 2021, with the Delta variant gradually being replaced by the Omicron variant among COVID-19 cases, there has been a very sharp increase in the number of PIMS cases since early December 2021, and this number remains high in early 2022.

• The four- to five-week lag observed during the first waves of the epidemic between the peaks in SARS-CoV-2 infections and those in PIMS cases is no longer evident in recent weeks, suggesting that the Omicron variant may have a different impact compared to previous variants, both in terms of the number of consecutive PIMS cases and the time lag between infection and the onset of these cases. A resurgence in the number of these cases is possible in the coming weeks.

• 400 cases (39%) involved girls. The median age of cases was 7 years (25% of cases were ≤ 4 years old and 75% ≤ 11 years old).

• More than eight out of 10 cases were confirmed by positive RT-PCR and/or serology for SARS-CoV-2 (n=864, 85%). A link to the virus was probable in 34 patients, or 3% of cases (exposure to a positive individual or suggestive CT scan), and considered possible in 40 patients (4%). For the remaining 84 patients (8%), this link could not be established.

• In France, the cumulative incidence of PIMS associated with COVID-19 was estimated at 6.5 cases per 100,000 inhabitants in the population under 18 years of age.