Epidemiology and role of SARS-CoV-2 Linkage in Paediatric Inflammatory Multisystem Syndrome (PIMS): A Canadian Paediatric Surveillance Program National Prospective Study

BackgroundPaediatric inflammatory multisystem syndrome (PIMS) is a rare but serious condition temporally associated with SARS-CoV-2 infection. Using the Canadian Paediatric Surveillance Program (CPSP), a national surveillance system, we aimed to 1) study the impact of SARS-CoV-2 linkage on clinical and laboratory characteristics, and outcomes in hospitalized children with PIMS across Canada 2) identify risk factors for ICU admission, and 3) establish the minimum national incidence of hospitalizations due to PIMS and compare it to acute COVID-19. MethodsWeekly online case reporting was distributed to the CPSP network of more than 2800 pediatricians, from March 2020 to May 2021. Comparisons were made between cases with respect to SARS-CoV-2 linkage. Multivariable modified Poisson regression was used to identify risk factors for ICU admission and Minimum incidence proportions were calculated. FindingsIn total, 406 PIMS cases were analyzed, of whom 202 (49{middle dot} 8%) had a positive SARS-CoV-2 linkage, 106 (26{middle dot} 1%) had a negative linkage, and 98 (24{middle dot} 1%) had an unknown linkage. The median age was 5{middle dot} 4 years (IQR 2{middle dot} 5-9{middle dot} 8), 60% were male, and 83% had no identified comorbidities. Compared to cases with a negative SARS-CoV-2 linkage, children with a positive SARS-CoV-2 linkage were older (8{middle dot} 1 years [IQR 4{middle dot} 2-11{middle dot} 9] vs. 4{middle dot} 1 years [IQR 1{middle dot} 7-7{middle dot} 7]; p<0{middle dot} 001), had more cardiac involvement (58{middle dot} 8% vs. 37{middle dot} 4%; p<0{middle dot} 001), gastrointestinal symptoms (88{middle dot} 6% vs. 63{middle dot} 2%; p<0{middle dot} 001), and shock (60{middle dot} 9% vs. 16{middle dot} 0%; p<0{middle dot} 001). At-risk groups for ICU admission include children [&ge;] 6 years and those with a positive SARS-CoV-2 linkage. No deaths were reported. The minimum incidence of PIMS hospitalizations during the study period was 5{middle dot} 6 hospitalizations per 100,000 population <18 years. InterpretationWhile PIMS is rare, almost 1 in 3 hospitalized children required ICU admission and respiratory/hemodynamic support, particularly those [&ge;] 6 years and with a positive SARS-CoV-2 linkage. FundingFinancial support for the CPSP was received from the Public Health Agency of Canada.