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.

Our data suggest that Khine's formula for predicting the appropriate tracheal tube size underestimates optimal size by 0.5 mm. We therefore recommend the use of the following formula: internal diameter of the CET = [age/4 + 3.5] in children >1 year of age which may be applied without increased risk of complications. The rate of tracheal reintubation as well as the detected leaks supports these recommendations.

During the initial postoperative course after bariatric surgery, physical examination of the abdomen is unreliable to identify surgical complications. The presence of respiratory signs should prompt abdominal investigations before the onset of organ failure. An urgent laparoscopy, as soon as abnormal clinical events are detected, is a valuable tool for early diagnosis and could shorten the delay in treatment.