key: cord-0793255-if186qgh authors: Ulyte, A.; Radtke, T.; Abela, I.; Haile, S. H.; Braun, J.; Jung, R.; Berger, C.; Trkola, A.; Fehr, J.; Puhan, M. A.; Kriemler, S. title: Seroprevalence and immunity of SARS-CoV-2 infection in children and adolescents in schools in Switzerland: design for a longitudinal, school-based prospective cohort study date: 2020-09-02 journal: nan DOI: 10.1101/2020.08.30.20184671 sha: 3e428e568fe64887dd711b353c9360153bb8b081 doc_id: 793255 cord_uid: if186qgh Introduction Seroprevalence and transmission routes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in children and adolescents, especially in school setting, are not clear. Resulting uncertainty is reflected in very different decisions on school closures and reopenings across countries. The aim of this longitudinal cohort study is to assess the extent and patterns of seroprevalence of SARS-CoV-2 antibodies in school-attending children repeatedly. It will examine risk factors for infection, relationship between seropositivity and symptoms, and temporal persistence of antibodies. Additionally, it will include testing of school personnel and parents. Methods and analysis The study (Ciao Corona) will enroll a regionally representative, random sample of schools in the canton of Zurich, where 18% of the Swiss population live. Children aged 5 to 16 years, attending classes in primary and secondary schools are invited. Venous blood and saliva samples are collected for SARS-CoV-2 serological testing after the first wave of infections (June/July 2020), in fall (October/November 2020), and after winter (March/April 2021). Venous blood is also collected for serological testing of parents and school personnel. Bi-monthly questionnaires to children, parents and school personnel cover SARS-CoV-2 symptoms and tests, health, preventive behavior, lifestyle and quality of life information. Total seroprevalence and cumulative incidence will be calculated. Hierarchical Bayesian logistic regression models will account for sensitivity and specificity of the serological test in the analyses and for the complex sampling structure, i.e., clustering within classes and schools. Ethics and dissemination The study was approved by the Ethics Committee of the Canton of Zurich, Switzerland (2020-01336). The results of this study will be published in peer-reviewed journals and will be made available to study participants and participating schools, the Federal Office of Public Health, and the Educational Department of the canton of Zurich. Trial registration number NCT04448717. Introduction Seroprevalence and transmission routes of severe acute respiratory syndrome 23 coronavirus 2 (SARS-CoV-2) infection in children and adolescents, especially in school 24 setting, are not clear. Resulting uncertainty is reflected in very different decisions on school 25 closures and reopenings across countries. The aim of this longitudinal cohort study is to 26 assess the extent and patterns of seroprevalence of SARS-CoV-2 antibodies in school-27 attending children repeatedly. It will examine risk factors for infection, relationship between 28 seropositivity and symptoms, and temporal persistence of antibodies. Additionally, it will 29 include testing of school personnel and parents. 30 The study (Ciao Corona) will enroll a regionally representative, 31 random sample of schools in the canton of Zurich, where 18% of the Swiss population live. 32 Children aged 5 to 16 years, attending classes in primary and secondary schools are invited. 33 Venous blood and saliva samples are collected for SARS-CoV-2 serological testing after the 34 first wave of infections (June/July 2020), in fall (October/November 2020), and after winter 35 (March/April 2021). Venous blood is also collected for serological testing of parents and 36 school personnel. Bi-monthly questionnaires to children, parents and school personnel cover 37 SARS-CoV-2 symptoms and tests, health, preventive behavior, lifestyle and quality of life 38 information. Total seroprevalence and cumulative incidence will be calculated. Hierarchical 39 Bayesian logistic regression models will account for sensitivity and specificity of the 40 serological test in the analyses and for the complex sampling structure, i.e., clustering within 41 classes and schools. 42 Ethics and dissemination The study was approved by the Ethics Committee of the Canton 43 of Zurich, Switzerland (2020-01336). The results of this study will be published in peer-44 reviewed journals and will be made available to study participants and participating schools, is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 2, 2020. . https://doi.org/10.1101/2020.08.30.20184671 doi: medRxiv preprint Introduction 62 63 Decisions on school opening or closing during the severe acute respiratory syndrome 64 coronavirus 2 (SARS-CoV-2) pandemic vary greatly across and even within countries. While 65 some countries kept schools mostly open (e.g., Sweden, Australia) or reopened early (e.g., 66 Denmark), others opted for prolonged closing with decision on reopening in late summer 67 2020 pending (e.g., the US, Italy, Ireland). Early school closure in response to pandemic was 68 partly guided by analogy of transmission of other viruses, such as influenza [1, 2] is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 2, 2020. . https://doi.org/10.1101/2020.08.30.20184671 doi: medRxiv preprint schooling), then partly reopened until June 7 th (e.g., teaching in half-classes, restricting larger 89 group activities, reducing school care groups), when regular teaching resumed again [15] . is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 2, 2020. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 2, 2020. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 2, 2020. . https://doi.org/10.1101/2020.08.30.20184671 doi: medRxiv preprint is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 2, 2020. . https://doi.org/10.1101/2020.08.30.20184671 doi: medRxiv preprint attending the selected classes are invited, except in mixed-age classes (only students from the 172 eligible grades invited). 173 Primary schools are selected randomly, and the closest secondary school 174 geographically is matched. The targeted number of schools to enroll per district ranges from 175 2 to 10 depending on the district size. After initial invitation round, school participation rate 176 is assessed and additional schools are selected within required districts, until the aimed 177 number is reached, or further recruitment would not be feasible. Population sizes and targeted 178 number of enrolled schools within districts is depicted in Figure 1 . 179 The overall targeted number of schools is 58 (29 primary and 29 secondary schools). is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 2, 2020. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 2, 2020. . https://doi.org/10.1101/2020.08.30.20184671 doi: medRxiv preprint precautions. First, information is provided, child's identity and consent confirmed, and saliva 218 collected. Venous blood samples will be collected at supine position with the help of 219 anesthetic patches, applied 45-60 min prior to venipuncture. Participating children receive a 220 small age-appropriate gift (worth 5-20$) at the end of each testing. 221 Adults will be invited for testing in schools or at a testing center. Personal support to 222 fill in the online questionnaire will be offered during testing. Venous blood will be collected. 223 Collected samples are stored, cooled and transported to the laboratory daily after the testing is 224 finished. 225 226 Summary information of specimen and questionnaires collected is provided in Table 1 . is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 2, 2020. . https://doi.org/10.1101/2020.08.30.20184671 doi: medRxiv preprint For each child and adult participant, one sample (9 mL for children and 4.9 mL for 238 adults) of venous blood will be collected for the assessment of SARS-CoV-2 antibodies. 239 Plasma will be separated, aliquoted into 1mL tubes and biobanked at -20⁰C until testing. 240 Saliva samples are collected in clean tubes and enriched with virus transport medium. 241 Saliva will first be validated for serological testing. If serological testing in saliva is deemed 242 sufficiently accurate, venous blood sampling might not be necessary in further testing phases. 243 Conversely, if serological testing in saliva is deemed not accurate enough, saliva sample 244 collection will not be continued. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 2, 2020. Descriptive analysis of participant sociodemographic, lifestyle, and behavior information will 283 be performed. Total seroprevalence and cumulative incidence will be calculated, as well as 284 age-, time-and region-specific estimates. In order to also include the sensitivity and 285 specificity of the serological test in the analyses and account for the complex sampling 286 structure (clustering within classes and schools), hierarchical Bayesian logistic regression 287 models will be used. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 2, 2020. . https://doi.org/10.1101/2020.08.30.20184671 doi: medRxiv preprint Associations with health and quality of life outcomes will be assessed with multiple 291 regression models. Other planned estimates include proportion of seropositive individuals 292 who have been asymptomatic, risk factors for infection at individual and school level. 293 Associations of levels of IgG, IgM and IgA antibodies with symptoms and risk factors will be 294 assessed. 295 296 The study was initiated together with the Educational Department of the canton of Zurich. 298 Several school principals were consulted during the development of the protocol to ensure 299 feasibility of the planned study procedures. Early feedback was collected from children and 300 parents invited to participate, in order to adapt the communication strategies and channels. 301 Further feedback was collected from enrolled children and school principals during the first 302 testing phase, in order to adapt subsequent testing phases and adult testing. Numerous online 303 informational sessions, encouraging open exchange and feedback, were organized for school 304 principals, personnel and parents of the children. Results of individual tests will be 305 communicated to the participants, and overall study results disseminated to participating 306 schools. Findings will be disseminated in lay language in the national and local press, to the 307 national and regional educational and public health departments and to the website of the 308 study. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 2, 2020. . https://doi.org/10.1101/2020.08.30.20184671 doi: medRxiv preprint explain the role of schools in order to define the necessary and sufficient preventive measures 317 to balance infection control and impact of school closure. 318 Currently available population-based seroprevalence studies, which have included 319 children, were mostly conducted in household setting. In May 2020, only 0.8% of children 320 aged 5-9 years were seropositive for SARS-Cov-2 in Geneva, Switzerland, in contrast to 321 9.6% of children and adolescents aged 10-19 years and 9.9% of adults aged 20-49 years [4] . 322 In April and May 2020, 3.8% of children and adolescents aged 0-19 years were seropositive 323 in Spain, compared to 4.5% to 5.0% in older age groups [5] . In contrast, the current study 324 will primarily consider schools. By analyzing seroprevalence on individual, class and school 325 level, as well as in parents and school personnel, we will be able to identify clusters within 326 these structures. Such knowledge could help to decide if individual classes or whole schools 327 need to be closed to prevent SARS-CoV-2 infection spread. In addition, by testing the entire 328 school personnel, it will inform which employees at schools are the most susceptible to 329 infection. 330 Only few related planned or ongoing studies have been reported worldwide. In the 331 UK, a study run by Public Health England aims to test seroprevalence in child care facilities 332 and schools in England in May/June, July, and end of autumn 2020 [17] . However, it is not 333 clear if the sampling of schools will be random or stratified by regions or if the structure 334 within schools (classes) will be considered. A smaller study in Berlin, Germany, aims to test 335 24 randomly selected schools, including 20-40 children and adolescents (500-1000 in total) 336 and 5-10 staff members at each school [18] . 337 The results of this study will likely be generalizable to other cantons in Switzerland 338 and also worldwide, particularly to high-and middle-income countries. The canton of Zurich 339 includes both urban and rural settings, as well as an ethnically and linguistically diverse 340 population. Although the rates of seroprevalence are always location-and time-specific, we 341 believe that the longitudinal design will allow us to investigate many stages of the pandemic. 342 . CC-BY-ND 4.0 International license It is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 2, 2020. . https://doi.org/10.1101/2020.08.30.20184671 doi: medRxiv preprint Due to urgency to launch the study, it faces a few challenges. First, high participation 343 rate of schools and children is required for sufficient power to analyze different regions and 344 clusters within classes and schools. We believe that the high public interest will lead to 345 increased participation, which could otherwise be rather limited in a study collecting venous 346 blood samples in children. In fact, in the initial testing phase in June/July 2020, 55 schools 347 and more than 2500 children were successfully enrolled. Second, the protocol of the 348 longitudinal study will have to be flexible as the pandemic and serological testing methods 349 develop. For this reason, the specific time points of serological testing cannot be fixed in 350 advance (e.g., in case of school closure during the course of the study). Similarly, in further 351 testing phases, it might be sufficient to do the serological testing in saliva or blood, 352 depending on the outcome of the validation of serological testing in saliva. Finally, in order 353 to recruit a sufficient number of schools still before school summer holidays, three rounds of 354 invitations were needed, leading to potential over-or under-sampling of schools in certain 355 districts. However, the sampling discrepancies can be adjusted with weighing of results. 356 357 This population-based cohort study with randomly selected schools and classes across the age 359 range for mandatory school time offers a unique opportunity to observe the longitudinal 360 spread of SARS-CoV-2 infection in children in schools, as well as in their parents and school 361 personnel, thus studying the whole school community. It will report SARS-CoV-2 362 seroprevalence in children by age groups and regions, provide essential information on 363 possible transmission routes and immunity over time, and assess individual and school-level 364 risk factors for infection. The longitudinal design will allow describing temporal trends of 365 immunity to SARS-CoV-2 and evaluating effects of school structure and preventive 366 measures. It will inform goal-oriented policy decisions in school management during 367 subsequent outbreaks. 368 . CC-BY-ND 4.0 International license It is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 2, 2020. . https://doi.org/10.1101/2020.08.30.20184671 doi: medRxiv preprint Ethics and dissemination 370 The study was approved by the Ethics Committee of the Canton of Zurich, Switzerland 371 (2020-01336). The results of this study will be published in peer-reviewed journals and will 372 be made available to study participants and participating schools, the Federal Office of Public 373 Health of Switzerland, and the Educational Department of the canton of Zurich. 374 375 . CC-BY-ND 4.0 International license It is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 2, 2020. . https://doi.org/10.1101/2020.08.30.20184671 doi: medRxiv preprint Reactive school closure weakens the network 376 of social interactions and reduces the spread of influenza Closure of schools during an influenza 379 pandemic School closure and management practices 381 during coronavirus outbreaks including COVID-19: a rapid systematic review Seroprevalence of anti-SARS-CoV-2 IgG 384 antibodies in Geneva, Switzerland (SEROCoV-POP): a population-based study Prevalence of SARS-CoV-2 in 387 ENE-COVID): a nationwide, population-based seroepidemiological study Spread of SARS-CoV-2 in the 390 Icelandic Population Transmission and Children: The Child is Not to 392 Blame Social Contacts and Mixing Patterns Relevant to the 394 Spread of Infectious Diseases National Centre for Immunisation Research and Surveillance (NCIRS). COVID-19 in Acknowledgements We greatly appreciate the uncomplicated and supportive collaboration 427