Multisystem inflammatory syndrome in children rose and fell with the first wave of the COVID‐19 pandemic in France

Carbajal, Ricardo; Lorrot, Mathie; Levy, Yael; Grimprel, Emmanuel; Lecarpentier, Thibault; Heritier, Sebastien; Faivre, Judith; Schnuriger, Aurélie; Parisot, Pauline; Blondiaux, Eléonore; Loschi, Solene; Rivière, Simon; Guilbert, Julia; Romain, Anne‐Sophie; Leger, Pierre‐Louis; Guedj, Romain

AIM: This study determined the influence of the COVID‐19 pandemic on the occurrence of multisystem inflammatory syndrome in children (MIS‐C) and compared the main characteristics of MIS‐C and Kawasaki disease (KD). METHODS: We included patients aged up to 18 years of age who were diagnosed with MIS‐C or KD in a paediatric university hospital in Paris from 1 January 2018 to 15 July 2020. Clinical, laboratory and imaging characteristics were compared, and new French COVID‐19 cases were correlated with MIS‐C cases in our hospital. RESULTS: There were seven children with MIS‐C, from 6 months to 12 years of age, who were all positive for the virus that causes COVID‐19, and 40 virus‐negative children with KD. Their respective characteristics were as follows: under 5 years of age (14.3% vs. 85.0%), paediatric intensive care unit admission (100% vs. 10.0%), abdominal pain (71.4% vs. 12.5%), myocardial dysfunction (85.7% vs. 5.0%), shock syndrome (85.7% vs. 2.5%) and mean and standard deviation C‐reactive protein (339 ± 131 vs. 153 ± 87). There was a strong lagged correlation between the rise and fall in MIS‐C patients and COVID‐19 cases. CONCLUSION: The rise and fall of COVID‐19 first wave mirrored the MIS‐C cases. There were important differences between MIS‐C and KD.