SARS-CoV-2 variants and the risk of Pediatric Inflammatory Multisystem Syndrome temporally associated with SARS-CoV-2 in children in Germany

Abstract Purpose: To investigate the risk of Pediatric Inflammatory Multisystem Syndrome temporally associated with SARS-CoV-2 (PIMS-TS) in children depending on periods with different dominant variants of concern (VOC) of SARS-CoV-2.Methods: The risk of developing PIMS-TS in three phases of the pandemic with different VOC (Alpha, Delta, and Omicron) was calculated using data of rtPCR confirmed SARS-CoV-2 infections extracted from the German statutory notification system and reports of cases with PIMS-TS captured by a national, prospective registry. Overall and age group-specific rate ratios of PIMS-TS rates in the different observation periods, using the Alpha period as the baseline, were calculated.Results: The rate of PIMS-TS changed significantly over time. During April-August 2021, with dominant VOC Alpha_B.1.1.7, the PIMS-TS rate was 6.19 (95% confidence intervals (95% CI) 5.17, 7.20), decreased to 1.68 (95% CI 1.49, 1.87) in August 2021 to January 2022 with Delta_AY and to 0.89 (95% CI 0.79, 1.00) in January-April 2022 with Omicron_BA as dominant VOC. This corresponds to a decrease in PIMS-TS rate of 73% (rate ratio 0.271, 95% CI 0.222; 0.332) and 86% (rate ratio 0.048, 95% CI 0.037; 0.062), respectively, compared to the Alpha period. Rate ratios were almost identical for all age groups.Conclusion: The data strongly suggest a relation of the risk for PIMS-TS to the prevailing VOC with the highest risk related to Alpha_B.1.1.7 and the lowest with Omicron_BA. Uniformity of the decrease across age groups does not suggest a major role for vaccination on the risk of PIMS-TS in infected children.