COVID-19: Longitudinal Study of Seroprevalence of SARS-CoV-2 Antibodies and Development of Immunity in School Children

Study Overview
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Brief Summary
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There is a lack of knowledge about how many children are infected with SARS-CoV-2, how often they are asymptomatic, and how long the immunity persists. The main purpose of this study is to measure antibodies to SARS-CoV-2, symptoms, and risk factors in a representative cohort of children and adolescents in the canton of Zurich, Switzerland, shortly after re-opening of the school system and thereafter. The study also investigates antibodies to SARS-CoV-2 in parents of the children and school personnel.

Detailed Description
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The role of children and adolescents in the transmission of SARS-CoV-2 remains highly unclear and has been a key question since the early days of the pandemic. It has important consequences for policy decisions, especially concerning the opening of the schools, sport facilities and intergenerational contacts. However, the information on true infection rate and seroprevalence of SARS-CoV-2 is not known in children in Switzerland (and globally), as testing was limited to risk groups and those with SARS-CoV-2 coronavirus disease 2019 (COVID-19) related symptoms. In addition, indications for testing were not uniform and handled heterogeneously. Hence, it is not known whether children are less frequently infected or simply less symptomatic. This study builds up a system to monitor the seroprevalence of SARS-CoV-2 in children and adolescents who attend school in the canton of Zürich, Switzerland. The investigators aim to assess children of randomly selected primary and secondary schools during the first weeks of re-entering school from all districts of the canton of Zurich in June and July 2020, after the temporary closure due to COVID-19 pandemic, and again in October/November 2020, February/March 2021, November/December 2021, and again in the second half of 2022. The detailed time plan including possible further assessments will be defined depending on the evolution of the pandemic (e.g., 2023). A follow-up capturing health status, symptoms and behaviors over time is important, since it is currently under investigation whether persons may be at risk for reinfection. Thus, a longitudinal assessment is crucial to determine the extent and duration of immunity. In addition, the seroprevalence of SARS-CoV-2 in the parents of the participating children will be tested in August/September 2020, to examine clusters of infections in households. Seroprevalence of SARS-CoV-2 in school personnel will be tested in August/September 2020 and subsequently in October/November 2020 and February/March 2021, to examine temporal changes in the seroprevalences in the whole school community. Further testing of adults is not planned. In different subpopulations, further in-depth analysis of immunity markers will be performed in the future. This study complements the ongoing coordinated efforts of seroprevalence studies in adults in Switzerland, through the Swiss School of Public Health (SSPH+) coordinated CORONA IMMUNITAS studies.

Official Title
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Seroprevalence of SARS-CoV-2 Antibodies and Development of Immunity in a Public School Population - a Population-based Observational Study to Inform Policy Making

Conditions
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SARS-CoV 2, COVID-19

Intervention / Treatment
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* Diagnostic Test: COVID-19 Antibody testing


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Any school child residing in Switzerland aged 5 years or older and attending a consenting to participate public or private school that hosts classes of interest (grade 1 through 9) in the canton of Zürich. Parents of participating children. Personnel employed in the participating schools. No acute respiratory and SARS-CoV-2 infection: In case of unknown respiratory infection, no presence of symptoms for at least 48 hours. In case of confirmed SARS-CoV-2 infection: inclusion at the earliest 21 days from PCR-positive diagnosis after the onset of potential symptoms and no presence of symptoms for at least 48 hours (according to Standard of Care). Informed consent of parents or legal guardians and children, or the adult participant. Exclusion Criteria: No informed consent by schools or children, or the adult participant. Schools with <40 students in one of the sampled grades (1, 2, 4, 5, 7, or 8). Children of Kindergarten age and younger. Suspicion of acute COVID-19 infection. Special need schools.

Ages Eligible for Study
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Minimum Age: 5 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Children and adolescents<br>Children and adolescents in primary and secondary schools (aimed sample size: 2500) | Diagnostic Test: COVID-19 Antibody testing<br>* COVID-19 Antibody testing in venous blood and/or saliva samples.<br>|
| Parents<br>Parents of participating children (aimed sample size: 3000) | Diagnostic Test: COVID-19 Antibody testing<br>* COVID-19 Antibody testing in venous blood and/or saliva samples.<br>|
| School personnel<br>School personnel (teaching, administrative, maintenance, etc.) (aimed sample size: 2500) | Diagnostic Test: COVID-19 Antibody testing<br>* COVID-19 Antibody testing in venous blood and/or saliva samples.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Seroprevalence of SARS-CoV-2 IgG, IgM and/or IgA antibodies | Seroprevalence of SARS-CoV-2 IgG, IgM and/or IgA antibodies in randomly selected 5- to 16-year-old population of school-children, their parents, and school personnel, after the peak phase of the first major wave shortly after re-opening of schools in the canton of Zürich, Switzerland. | at inclusion | 
| Seroprevalence of SARS-CoV-2 IgG, IgM and/or IgA antibodies | Seroprevalence of SARS-CoV-2 IgG, IgM and/or IgA antibodies in randomly selected 5- to 16-year-old population of school-children and school personnel after 4-5 after recruitement in the canton of Zürich, Switzerland. | Month 4-5 | 
| Seroprevalence of SARS-CoV-2 IgG, IgM and/or IgA antibodies | Seroprevalence of SARS-CoV-2 IgG, IgM and/or IgA antibodies in randomly selected 5- to 16-year-old population of school-children and school personnel after 8-9 months after recruitment in the canton of Zürich, Switzerland. | Month 8-9 | 
| Seroprevalence of SARS-CoV-2 IgG antibodies | Seroprevalence of SARS-CoV-2 IgG antibodies in randomly selected 5- to 16-year-old population of school-children and school personnel after 17-18 months after recruitment in the canton of Zürich, Switzerland. | Month 17-18 | 
| Seroprevalence of SARS-CoV-2 IgG antibodies | Seroprevalence of SARS-CoV-2 IgG antibodies in randomly selected 5- to 16-year-old population of school-children and school personnel after 24-30 months after recruitment in the canton of Zürich, Switzerland. | Month 24-30 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Presence of self-reported symptoms | Presence of symptoms (from January 2020) suggestive of a common cold, influenza and similar upper respiratory tract infections prior to the first study visit. | at inclusion | 
| Proportion of seropositive children reporting COVID-19 related symptoms from January 2020 | Proportion of seropositive children reporting symptoms suggestive of a common cold, influenza and similar upper respiratory tract infections between January 2020 and first study visit. | at inclusion | 
| Presence of self-reported symptoms | Presence of symptoms (from January 2020) suggestive of a common cold, influenza and similar upper respiratory tract infections during the follow-up. | within 36 months of follow-up | 
| Incidence of symptoms in initially seropositive participants | Incidence of self-reported symptoms and SARS-CoV-2 infections after the first study visit in initially seropositive participants. | within 36 months of follow-up | 
| Proportion of participants, seronegative at inclusion, with symptoms in the follow-up | Proportion of seronegative participants of the first investigation wave who will self-report symptoms and infection with SARS-CoV-2. | within 36 months of follow-up | 
| Presence of risk factors for infection at inclusion (assessment via custom questionnaire) | Potential personal (socioeconomic characteristics, health status, presence of infection in family, personal hygiene and social distancing measures) and school-level (implementation of informational, social distancing and hygiene measures at school) risk and preventive factors for SARS-CoV-2 infection prior to the study. Questionnaire includes HBSC and custom questions. | at inclusion | 
| Presence of risk factors for infection during follow-up (assessment via custom questionnaire) | Potential personal (socioeconomic characteristics, health status, presence of infection in family, personal hygiene and social distancing measures) and school-level (implementation of informational, social distancing and hygiene measures at school) risk and preventive factors for SARS-CoV-2 infection during the follow-up. Questionnaire includes HBSC and custom questions. | within 36 months of follow-up | 
| Self-reported lifestyle changes of participants at inclusion | Changes in lifestyle during the lock-down, compared to prior to it: frequency and duration (in hours, daily) of physical activity, duration (in hours, daily) of sleep, duration of screen-based media-use (in hours, daily). This outcome is measured only in the children population. | at inclusion | 
| Self-reported lifestyle changes of participants during follow-up | Changes in lifestyle after the lock-down and school reopening, compared to during lock-down: frequency and duration (in hours, daily) of physical activity, duration (in hours, daily) of sleep, duration of screen-based media-use (in hours, daily). This outcome is measured only in the children population. | within 36 months of follow-up | 
| Self-reported mental well-being (KINDL questionnaire) | Changes over the study time in mental well-being of the participants during and after the lock-down: frequency scale (never/rarely/sometimes/often/always) of self-reported stress, anxiety, self-confidence feelings in the last 7 days. This outcome is measured only in the children population. | within 36 months of follow-up | 
| Self-reported mental well-being (HBSC questionnaire) | Changes over the study time in mental well-being of the participants during and after the lock-down: frequency scale (daily/weekly/monthly/rarer) of self-reported sadness, anxiety and sleeping problems (HBSC questionnaire question on mental well-being). This outcome is measured only in the children population. | within 36 months of follow-up | 
| Self-reported quality of life (KINDL questionnaire) | Changes over the study time in quality-of-life of the participants during and after the lock-down: frequency scale (never/rarely/sometimes/often/always) assessment of self-reported positive and negative social interactions with family, friends and in the school environment in the last 7 days. This outcome is measured only in the children population. | within 36 months of follow-up | 
| Prevalence of seropositive SARS-Cov-2 clusters in schools at inclusion | Prevalence of clusters of seropositive children, adolescents, and school personnel within schools and classes at baseline. | at inclusion | 
| Incidence of seropositive SARS-Cov-2 clusters in schools during the follow-up | Incidence of clusters of seropositive children, adolescents, and school personnel within schools and classes during the follow-up. | within 36 months of follow-up | 
| Change in seropositive participants within school or class, depending on the initial proportion of seropositive participants | Impact of the number of children/adolescents and school personnel at a specific period (baseline, at the second and third testing date) within a school or class to the subsequent seropositivity within the same group. | within 36 months of follow-up | 
| Effect of risk factors and preventive measures on SARS-CoV-2 infection incidence within schools | Incidence of seropositive children and school personnel according to potential risk factors and preventive measures for SARS-CoV-2 infection within schools. | within 36 months of follow-up | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Seroprevalence, Seroepidemiology, School children, Switzerland, Schools, Households, Students