MIS-C incidence decreased throughout COVID-19 pandemic

Multisystem inflammatory syndrome in children (MIS-C) incidence decreased throughout the COVID-19 pandemic, according to a recent study.

MIS-C is an often serious condition that could require treatment in a pediatric intensive care unit. Challenges remain in diagnostic approach and treatment strategies despite growing awareness, and there is little information on the factors which lead to MIS-C pathogenesis.

As there is a lack of studies on how variants of COVID-19 trigger MIS-C, investigators conducted a study comparing the effects different variants had on MIS-C incidence, along with epidemiologic and clinical characteristics present in children hospitalized with MIS-C.

Children and young people aged under 18 years were evaluated for MIS-C incidence, clinical characteristics, and outcomes throughout 3 waves of the COVID-19 pandemic. Data was provided by the National Public Health Organization.

The predominant variant was recorded for each wave, making up 80% or more of the strains sequenced. The first wave was recorded from August 1, 2020, to January 31, 2021, the second from February 1, 2021, to July 31, 2021, and the third from August 1, 2021, to December 31, 2021.

Patient, demographic, clinical, and laboratory data was collected from 10 participating reference tertiary care centers. Reverse transcription polymerase chain reaction and serology of participants were also available. The rate of MIS-C incidence was calculated as the denominator of total pediatric COVID-19 cases.

There were 119 patients included in the study, 109 of which met criteria from the World Health Organization for MIS-C diagnosis. During the first wave, 26.9% of children diagnosed with MIS-C were hospitalized, 39.5% during the second, and 33.6% during the third.

In a 4-to-6-week period after the peak of COVID-19 infections, a peak of MIS-C cases was observed. Similar peak MIS-C cases followed peak COVID-19 cases by 4 to 6 weeks. 

The first wave of COVID-19 had an MIS-C incidence of 3.4 per 1000, the second 1.1 per 1000, and the third 0.25 per 1000. This showed a decrease throughout the 3 waves. While admissions to intensive care units were highest during the second wave, no significant differences in clinical findings or outcomes were found across the 3 waves.

Reference

Eleftheriou I, Maritsi D, Lampidi S, Charisi K, Vantsi P, Skourti K, et al. Decreasing incidence of the multisystem inflammatory syndrome in children over 3 pandemic waves. The Pediatric Infectious Disease Journal. 2022;42(2):122-124. doi:10.1097/INF.0000000000003766