Multisystem Inflammatory Syndrome in Children in Western Countries? Decreasing Incidence as the Pandemic Progresses?: An Observational Multicenter International Cross-sectional Study.

BACKGROUND: SARS-CoV-2 variations as well as immune protection after previous infections and/or vaccination may have altered the incidence of multisystemic inflammatory syndrome in children (MIS-C). We aimed to report an international time-series analysis of the incidence of MIS-C to determine if there was a shift in the regions or countries included into the study. METHODS: This is a multicenter, international, cross-sectional study. We collected the MIS-C incidence from the participant regions and countries for the period July 2020 to November 2021. We assessed the ratio between MIS-C cases and COVID-19 pediatric cases in children <18 years diagnosed 4 weeks earlier (average time for the temporal association observed in this disease) for the study period. We performed a binomial regression analysis for 8 participating sites [Bogotá (Colombia), Chile, Costa Rica, Lazio (Italy), Mexico DF, Panama, The Netherlands and Catalonia (Spain)]. RESULTS: We included 904 cases of MIS-C, among a reference population of 17,906,432 children. We estimated a global significant decrease trend ratio in MIS-C cases/COVID-19 diagnosed cases in the previous month ( P < 0.001). When analyzing separately each of the sites, Chile and The Netherlands maintained a significant decrease trend ( P < 0.001), but this ratio was not statistically significant for the rest of sites. CONCLUSIONS: To our knowledge, this is the first international study describing a global reduction in the trend of the MIS-C incidence during the pandemic. COVID-19 vaccination and other factors possibly linked to the virus itself and/or community transmission may have played a role in preventing new MIS-C cases.

Admissions to a large tertiary care hospital and Omicron BA.1 and BA.2 SARS-CoV-2 polymerase chain reaction positivity: primary, contributing, or incidental COVID-19.

OBJECTIVES: SARS-CoV-2 Omicron variants BA.1 and BA.2 seem to show reduced clinical severity compared with earlier variants. Therefore, we aimed to assess and classify the cause of hospitalization for patients with COVID-19 identified with these Omicron variants in our hospital. METHODS: A retrospective analysis was performed on all patients identified with the SARS-CoV-2 Omicron variant between December 23, 2021, and February 27, 2022. Patients with a positive SARS-CoV-2 polymerase chain reaction (PCR) upon clinical admission or during clinical admission were classified into four categories: (1) primary COVID-19, (2) admission-contributing COVID-19, (3) incidental COVID-19, and (4) undetermined COVID-19. RESULTS: We classified 172 COVID-19 Omicron patient admissions, including 151 adult and 21 pediatric patients. Of the adult patients, 45% were primary COVID-19 cases, 21% were admission-contributing, 31% were incidental, and 3% were undetermined. Of the pediatric patients, 19% were primary COVID-19 cases, 29% were admission-contributing, 38% were incidental, and 14% were undetermined. CONCLUSION: In the evolving landscape of COVID-19, the number of hospitalized patients with COVID-19 should be interpreted with caution. The different patient categories should be considered in public health policy decision-making and when informing the general public.