A population-based serological study of post-COVID syndrome prevalence and risk factors in children and adolescents. 11/29/22. Dumont R. Nat Commun.

This report is from a Swiss population study of 1,034 children, aged 6 months to 17 years, who were tested for anti-SARS-CoV-2 N antibodies December 2021-February 2022. Pediatric vaccinations were not available to participants until early January 2022. Their parents filled in a questionnaire on symptoms compatible with post-COVID syndrome lasting over 12 weeks. Of the 1,034 children tested, 570 (55.1%) were seropositive. Overall, 24% has a prior test confirming SARS-CoV-2 infection, and 19% had had clinical symptoms consistent with COVID-19. Both were far more prevalent in the seropositive cohort, (by a factor of ~8x). The sex- and age-adjusted prevalence of children with persistent symptoms was 9.1% among seropositive children and 5.0% among seronegative children, with an adjusted prevalence difference (ΔaPrev) = 4.1%. Stratifying by age group, only those 12-17 years of age displayed a substantial risk of having post-COVID symptoms (ΔaPrev = 8.3%). Identified risk factors for post-COVID syndrome were older age, lower socioeconomic status and chronic health conditions, especially asthma.

SAB Comment: This study is useful in estimating the population’s prevalence of long COVID in young children (0%) and in adolescents (8.3%) of all those with positive serologies but does not estimate a symptomatic COVID-infected adolescent’s risk of long COVID (which may be significantly higher). Because pediatric vaccinations began in Switzerland in January 2022, the study could not assess the effect of prior vaccination on persistent symptoms, as not enough participants were vaccinated.

https://www.nature.com/articles/s41467-022-34616-8