Multisystem inflammatory syndrome in children during the first two years of the COVID-19 pandemic in Luxembourg

Abstract

ObjectiveEstimate the incidence of multisystem inflammatory syndrome (MIS-C) in children (0–15 years), the role of SARS-CoV-2 variants during the first two years of COVID-19 pandemic in Luxembourg; and describe the demographic, biological and clinical characteristics of the patients.MethodObservational retrospective cohort study. Cases between March 2020 and February 2022 were ascertained from the national registry of MIS-C cases by a retrospective review of medical records. Reported SARS-CoV-2 infections were obtained from the national COVID-19 surveillance system. We calculated monthly MIS-C incidence, the ratio between MIS-C and SARS-CoV-2 infections and associated rate ratios by the periods corresponding to the circulation of different variants.Results18 children were diagnosed with MIS-C among 35,200 reported infections. The incidence rate of MIS-C was 7.2 [95% confidence interval (CI) 4.5–11.4] per 1,000,000 person-months. A higher incidence of MIS-C was observed between September and December 2021, corresponding to the circulation of the Delta variant than during the first year of the pandemic (RR 3.6, 95% CI, 1.1–12.3). The lowest rate of MIS-C per infection was observed during the Omicron (RR 0.17, 95% CI, 0.03–0.82). Median age at diagnosis was 6.5 years. Previously healthy children made up 88% of MIS-C cases, none were vaccinated against SARS-CoV-2. 33% required intensive care. All patients recovered fully.ConclusionsMIS-C incidence and MIS-C risk per infection changed significantly over time during the first two years of COVID-19 pandemic. Monitoring of MIS-C incidence in future SARS-CoV-2 waves will be essential to guide public health interventions and vaccination policies for children.

Epidemiology, clinical characteristics and outcomes of multisystem inflammatory syndrome in children

“…We describe the epidemiology, clinical characteristics and outcomes of children with MIS‐C in Negeri Sembilan, Malaysia over a 30‐month period. The MIS‐C incidence was approximately 5.9 cases per 1,000,000 person‐months, which was comparable to other studies 16,17 . Despite reports of a decline in MIS‐C incidence during the Omicron wave, 18–20 we observed an increase in MIS‐C cases during this period.…”

“…The MIS-C incidence was approximately 5.9 cases per 1,000,000 person-months, which was comparable to other studies. 16,17 Despite reports of a decline in MIS-C incidence during the Omicron wave, [18][19][20] we observed an increase in MIS-C cases during this period. This discrepancy could be attributed to unique local epidemiological circumstances.…”

Contribution of SARS-CoV-2 infection preceding COVID-19 mRNA vaccination to generation of cellular and humoral immune responses in children

“…SARS-CoV-2 infection in healthy children is often asymptomatic or only accompanied by mild symptoms such as coughing or fever ( 1 ). However, SARS-CoV-2 infection in children can result in severe respiratory disease and other life-threatening diseases ( 2 ), such as multisystem inflammatory syndrome (MIS-C) ( 3 , 4 ). mRNA vaccines are widely used to prevent COVID-19 and were among the first highly successful vaccines during the rise of the COVID-19 pandemic ( 5 ).…”