BACKGROUND: Much remains unknown regarding the evolution of SARS-CoV-2 seroprevalence and variability in seropositive children in districts, schools and classes as only a few school-based cohort studies exist. Vaccination of children, initiated at different times for different age groups, adds additional complexity to the understanding of how seroprevalence developed in the school aged population. AIM: We investigated the evolution of SARS-CoV-2 seroprevalence in children and its variability in districts, schools and classes in Switzerland from June/July 2020 to November/December 2021. METHODS: In this school-based cohort study, SARS-CoV-2 antibodies were measured in primary and secondary school children from randomly selected schools in the canton of Zurich in October/November 2020, March/April 2021 and November/December 2021. Seroprevalence was estimated using Bayesian logistic regression to adjust for test sensitivity and specificity. Variability of seroprevalence between school classes was expressed as maximum minus minimum seroprevalence in a class and summarised as median (interquartile range). RESULTS: 1875 children from 287 classes in 43 schools were tested, with median age 12 years (range 6–17), 51% 12+ vaccinated. Seroprevalence increased from 5.6% (95% credible interval [CrI] 3.5–7.6%) to 31.1% (95% CrI 27.0–36.1%) in unvaccinated children, and 46.4% (95% CrI 42.6–50.9%) in all children (including vaccinated). Earlier in the pandemic, seropositivity rates in primary schools were similar to or slightly higher (<5%) than those in secondary schools, but by late 2021, primary schools had 12.3% (44.3%) lower seroprevalence for unvaccinated (all) subjects. Variability in seroprevalence among districts and schools increased more than two-fold over time, and in classes from 11% (95% CrI 7–17%) to 40% (95% CrI 22–49%). CONCLUSION: Seroprevalence in children increased greatly, especially in 2021 following introduction of vaccines. Variability in seroprevalence was high and increased substantially over time, suggesting complex transmission chains. Trial Registration: ClinicalTrials.gov NCT04448717

Background Long-term health consequences following acute SARS-CoV-2 infection, referred to as post-COVID-19 condition or Long COVID, are increasing, with population-based prevalence estimates for adults at around 20%. Persons affected by Long COVID report various health problems, yet evidence to guide clinical decision making remains scarce. Objective The present study aimed to identify Long COVID research priorities using a citizen science approach and solely considering the needs of those affected. Methods This citizen science study followed an iterative process of patient needs identification, evaluation and prioritisation. A Long COVID Citizen Science Board (21 persons with Long COVID, and seven with myalgic encephalomyelitis/chronic fatigue syndrome) and a Long COVID Working Group (25 persons with Long COVID, four patients with myalgic encephalomyelitis/chronic fatigue syndrome and one relative) were formed. The study included four activities: three remote meetings and one online survey. First, Board members identified the needs and research questions. Second, Working Group members and persons affected by Long COVID (241 respondents, 85.5% with Long COVID, 14.5% with myalgic encephalomyelitis/chronic fatigue syndrome and 7.1% relatives) evaluated the research questions on a 1–5 Likert scale using an online survey. Then the Board gave feedback on this evaluation. Finally, Board members set the priorities for research through voting and discussion. Results Sixty-eight research questions were generated by the Board and categorised into four research domains (medicine, healthcare services, socioeconomics and burden of disease) and 14 subcategories. Their average importance ratings were moderate to high and varied from 3.41 (standard deviation = 1.16) for sex-specific diagnostics to 4.86 (standard deviation = 0.41) for medical questions on treatment. Five topics were prioritised: “treatment, rehabilitation and chronic care management”, “availability of interfaces for treatment continuity”, “availability of healthcare structures”, “awareness and knowledge among professionals” and “prevalence of Long COVID in children and adolescents”. Conclusions To our knowledge, this is the first study developing a citizen-driven, explicitly patient-centred research agenda with persons affected by Long COVID, setting it apart from existing multi-stakeholder efforts. The identified priorities could guide future research and funding allocation. Our methodology establishes a framework for citizen-driven research agendas, suitable for transfer to other diseases. Supplementary Information The online version contains supplementary material available at 10.1007/s40271-022-00579-7.

Objectives: We investigated changes in adherence to physical activity (PA) and screen time (ST) recommendations of children and adolescents throughout the pandemic, and their association with health-related quality of life (HRQOL).Methods: 1,769 primary (PS, grades 1–6) and secondary (SS, 7–9) school children from Ciao Corona, a school-based cohort study in Zurich, Switzerland, with five questionnaires 2020–2022. HRQOL was assessed using the KINDL questionnaire. PA (≥60 min/day moderate-to-vigorous PA) and ST (≤2 h/day ST) recommendations followed WHO guidelines.Results: Adherence to PA recommendations dropped in 2020 (83%–59% PS, 77%–52% SS), but returned to pre-pandemic levels by 2022 (79%, 66%). Fewer children met ST recommendations in 2020 (74% PS, 29% SS) and 2021 (82%, 37%) than pre-pandemic (95%, 68%). HRQOL decreased 3 points between 2020 and 2022, and was 9.7 points higher (95% CI 3.0–16.3) in March 2021 in children who met both versus no recommendations.Conclusion: Adherence to WHO guidelines on PA and ST during the pandemic had a consistent association with HRQOL despite longitudinal changes in behavior.

Background Much remains unknown regarding the evolution of SARS-CoV-2 seroprevalence and variability in clustering of seropositive children in districts, schools, and classes as only a few school-based cohort studies exist. Vaccination of children, initiated at different times for different age groups, adds additional complexity to understand how seroprevalence developed in the school aged population. Aim We investigated the evolution of SARS-CoV-2 seroprevalence in children and clustering in districts, schools, and classes in Switzerland from June/July 2020 to Nov/Dec 2021. Methods SARS-CoV-2 antibodies were measured in primary and secondary school children from randomly selected schools in the canton of Zurich in Oct/Nov 2020, Mar/April, and Nov/Dec 2021. Variability of clustering in schools was expressed as maximum minus minimum seroprevalence in a class and summarized as median (interquartile range). Results 1854 children from 288 classes in 43 schools were tested, with median age 12 (range 6-17), 49% 12+ vaccinated. Seroprevalence increased from 5.6% (95% CrI: 3.5-7.6%) to 31.1% (27.0-36.1%) in unvaccinated children, and 46.4% (42.6-50.9%) in all children (including vaccinated). Earlier in the pandemic, seropositivity rates in primary schools were similar to those in secondary schools, but by late 2021, primary schools had 12.3% (44.3%) lower seroprevalence for unvaccinated (all) subjects. Variability in seroprevalence among districts and schools increased more than twofold over time, and in classes from 11% (7-17%) to 40% (22-49%). Conclusion Seroprevalence in children increased greatly, especially in 2021 following introduction of vaccines. Variability in seroprevalence was high and increased substantially over time, suggesting complex transmission chains.