ABSTRACT
Background and Objectives Evidence to date indicates that children, like adults, can present post-COVID syndrome. However, data on paediatric post-COVID syndrome re-mains unclear. In this study we present preliminary results regarding the duration and characteristics of paediatric persistent symptoms, stratifying by serological status, confirmed infection and age groups. Methods Children aged 6 months to 17 years of adults participating in a Geneva population-based cohort (Specchio-COVID19) and from a random sample drawn from state registries were invited to participate in the SEROCoV-KIDS longitudinal study, from December 1st 2021 to February 18th 2022. Children were tested for anti-SARS-CoV-2 antibodies targeting the nucle-ocapsid (N) protein which is only detected after SARS-CoV-2 infection. Parents filled-in a questionnaire on persistent symptoms (lasting over 12 weeks), compatible with post-COVID syndrome. We estimated sex-and age-adjusted prevalence using marginal prediction after logistic regres-sion. Findings Of 1015 children from 602 households, 555 (54.6%) were seropositive and 247 (24%) had a confirmed SARS-CoV-2 infection. Overall, 78 (7.7%) chil-dren had experienced persistent symptoms lasting over 12 weeks. The most frequent persistent symptoms declared among seropositives were fatigue, lower mood, insomnia and loss of smell. The adjusted prevalence of persistent symptoms among seropositive chil-dren was 9.0% (95%CI: 6.7-11.6) and of 5.0% (95%CI: 3.1-7.2) among ser-onegatives with an adjusted prevalence difference (ΔaPrev) of 4.0% (95%CI: 1.0-7.3). Stratifying by age group, we observed that the preva-lence of post-COVID was higher among adolescents (ΔaPrev = 8.3%;95%CI: 3.6-13.5) than among younger children (ΔaPrev = 2.1% (95%CI: -4.0-3.6) among 6-11 years old and ΔaPrev = 5.1% (95%CI:-2.4-12.8) among 0-5 years old). Interpretation A significant proportion of children, especially adolescents, experience symptoms lasting over 12 weeks after a SARS-CoV-2 infection. However, many parents declared persistent symptoms compatible with post-COVID in seronegative children, which highlights the complexity of identifying post-COVID, clinically and methodologically. We need further investiga-tion on timing of seroconversion and persistent symptoms, and potential other diagnoses. Nevertheless, the growing evidence of paediatric post-COVID indicates that more awareness in early detection and care man-agement are needed.