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Original article

Vol. 152 No. 2324 (2022)

SARS-CoV-2 seroprevalence in children, parents and school personnel from June 2020 to April 2021: cohort study of 55 schools in Switzerland

  • Agne Ulyte
  • Sarah R. Haile
  • Jacob Blankenberger
  • Thomas Radtke
  • Milo A. Puhan
  • Susi Kriemler
DOI
https://doi.org/10.4414/SMW.2022.w30193
Cite this as:
Swiss Med Wkly. 2022;152:w30193
Published
13.06.2022

Summary

BACKGROUND: Few studies have directly examined the incidence or seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in children, parents and teachers from the same school communities. This study aimed to describe SARS-CoV-2 seroprevalence within cantonal districts and school communities in children, parents and school personnel in June-September 2020 and March-April 2021 in the canton of Zürich, Switzerland.

METHODS: We invited children from 55 randomly selected primary and secondary schools and 275 classes within them to participate in the Ciao Corona study in June-July 2020. Parents of the participating children and all school personnel were invited in August-September 2020. Eligible classes, parents and school personnel were tested again in March-April 2021. Venous blood was tested for SARS-CoV-2 serology. We collected sociodemographic information of the participants in online questionnaires on enrolment in the study. We excluded vaccinated adults and those with unverified vaccination status from the main analysis. Seroprevalence estimates were adjusted for test accuracy. We assessed the variability of seroprevalence within and across cantonal districts and school communities and compared it with the per capita cumulative incidence of confirmed SARS-CoV-2 infections.

RESULTS: In June-September 2020, 2,473 children, 1,608 school personnel and 2,045 parents participated in the study. In June-September 2020, seroprevalence was low (4.4% to 5.8%) in all cohorts. In March-April 2021, seroprevalence in children and parents (18.1% and 20.9%) was slightly higher than in school personnel (16.9%). We observed a large variation in seroprevalence estimates of the three cohorts within and between districts and school communities, with the median ratio of children’s seroprevalence to per capita confirmed cases in district inhabitants of 3.1 (interquartile range 2.6 to 3.9). Seroprevalence was lower in children in the upper school level and their parents, but not teachers. Children’s seroprevalence was slightly higher in classes with infected main teachers and families with one infected parent and substantially higher in families with two infected parents.

CONCLUSIONS: We observed similar seroprevalence in children and parents, somewhat lower in school personnel in March-April 2021 and striking variation between districts and school communities. Children’s seroprevalence was higher in classes with infected main teachers and from families with infected parents.

References

  1. Ismail SA, Saliba V, Lopez Bernal J, Ramsay ME, Ladhani SN. SARS-CoV-2 infection and transmission in educational settings: a prospective, cross-sectional analysis of infection clusters and outbreaks in England [Internet]. Lancet Infect Dis. 2021 Mar;21(3):344–53. Available from: https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30882-3/fulltext https://doi.org/10.1016/S1473-3099(20)30882-3
  2. Viner RM, Russell SJ, Croker H, Packer J, Ward J, Stansfield C, et al. School closure and management practices during coronavirus outbreaks including COVID-19: a rapid systematic review [Internet]. Vol. 4, The Lancet Child and Adolescent Health. Elsevier B.V.; 2020. p. 397–404. Available from: https://www.thelancet.com/journals/lanchi/article/PIIS2352-4642(20)30095-X/fulltext
  3. Armann JP, Kirsten C, Galow L, Kahre E, Haag L, Dalpke A, et al. SARS-CoV-2 transmissions in students and teachers: seroprevalence follow-up study in a German secondary school in November and December 2020 [Internet]. BMJ Paediatr Open. 2021 Mar;5(1):e001036. Available from: https://bmjopen.bmj.com/content/11/6/e049876 https://doi.org/10.1136/bmjpo-2021-001036
  4. Zimmerman KO, Akinboyo IC, Brookhart MA, Boutzoukas AE, McGann KA, Smith MJ, et al.; ABC SCIENCE COLLABORATIVE. Incidence and Secondary Transmission of SARS-CoV-2 Infections in Schools [Internet]. Pediatrics. 2021 Apr;147(4):e2020048090. Available from: https://publications.aap.org/pediatrics/article/147/4/e2020048090/180871/Incidence-and-Secondary-Transmission-of-SARS-CoV-2 https://doi.org/10.1542/peds.2020-048090
  5. Liguoro I, Pilotto C, Bonanni M, Ferrari ME, Pusiol A, Nocerino A, et al. SARS-COV-2 infection in children and newborns: a systematic review [Internet]. Eur J Pediatr. 2020 Jul;179(7):1029–46. [cited 2022 Apr 7] Available from: https://link.springer.com/article/10.1007/s00431-020-03684-7 https://doi.org/10.1007/s00431-020-03684-7
  6. Chung E, Chow EJ, Wilcox NC, Burstein R, Brandstetter E, Han PD, et al. Comparison of Symptoms and RNA Levels in Children and Adults With SARS-CoV-2 Infection in the Community Setting [Internet]. JAMA Pediatr. 2021 Oct;175(10):e212025–212025. [cited 2022 Apr 7] Available from: https://jamanetwork.com/journals/jamapediatrics/fullarticle/2780963 https://doi.org/10.1001/jamapediatrics.2021.2025
  7. Viner RM, Mytton OT, Bonell C, Melendez-Torres GJ, Ward J, Hudson L, et al. Susceptibility to SARS-CoV-2 Infection Among Children and Adolescents Compared With Adults. JAMA Pediatr [Internet]. 2020 Sep 25 [cited 2020 Oct 4]; Available from: https://jamanetwork.com/journals/jamapediatrics/fullarticle/2771181
  8. Davies NG, Klepac P, Liu Y, Prem K, Jit M, Eggo RM ; CMMID COVID-19 working group. Age-dependent effects in the transmission and control of COVID-19 epidemics [Internet]. Nat Med. 2020 Aug;26(8):1205–11. [cited 2021 Jul 6] https://doi.org/10.1038/s41591-020-0962-9
  9. Roser M, Ritchie H, Ortiz-Ospina E, Hasell J. Coronavirus Pandemic (COVID-19) [Internet]. Published online at OurWorldInData.org. 2020 [cited 2021 Jul 1]. Available from: https://ourworldindata.org/coronavirus
  10. UNESCO. School closures caused by Coronavirus (Covid-19) [Internet]. 2020 [cited 2020 Dec 19]. Available from: https://en.unesco.org/covid19/educationresponse
  11. Theuring S, Thielecke M, van Loon W, Hommes F, Hülso C, von der Haar A, et al.; BECOSS Study Group. SARS-CoV-2 infection and transmission in school settings during the second COVID-19 wave: a cross-sectional study, Berlin, Germany, November 2020 [Internet]. Euro Surveill. 2021 Aug;26(34): Available from: https://pubmed.ncbi.nlm.nih.gov/34448448/ https://doi.org/10.2807/1560-7917.ES.2021.26.34.2100184
  12. Meuris C, Kremer C, Geerinck A, Locquet M, Bruyère O, Defêche J, et al. Transmission of SARS-CoV-2 After COVID-19 Screening and Mitigation Measures for Primary School Children Attending School in Liège, Belgium [Internet]. JAMA Netw Open. 2021 Oct;4(10):e2128757. Available from: https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2784812 https://doi.org/10.1001/jamanetworkopen.2021.28757
  13. Ulyte A, Radtke T, Abela IA, Haile SR, Braun J, Jung R, et al. 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 [Internet]. Int J Public Health. 2020 Dec;65(9):1549–57. Available from: https://pubmed.ncbi.nlm.nih.gov/33063141/ https://doi.org/10.1007/s00038-020-01495-z
  14. Ulyte A, Radtke T, Abela IA, Haile SR, Berger C, Huber M, et al. Clustering and longitudinal change in SARS-CoV-2 seroprevalence in school children in the canton of Zurich, Switzerland: prospective cohort study of 55 schools [Internet]. BMJ. 2021 Mar;372:n616. https://doi.org/10.1136/bmj.n616
  15. Fenwick C, Croxatto A, Coste AT, Pojer F, André C, Pellaton C, et al. Changes in SARS-CoV-2 Spike versus Nucleoprotein Antibody Responses Impact the Estimates of Infections in Population-Based Seroprevalence Studies. J Virol [Internet]. 2020; Available from: https://journals.asm.org/doi/10.1128/JVI.01828-20
  16. Puhan MA, Chiolero A, Fehr J, Cullati S. Overcoming spectrum bias for accurate SARS-CoV-2 seroprevalence estimates [Internet]. Vol. 373, The BMJ. BMJ Publishing Group; 2021. Available from: https://www.bmj.com/content/372/bmj.n561/rr
  17. Rogan WJ, Gladen B. Estimating prevalence from the results of a screening test [Internet]. Am J Epidemiol. 1978 Jan;107(1):71–6. Available from: https://pubmed.ncbi.nlm.nih.gov/623091/ https://doi.org/10.1093/oxfordjournals.aje.a112510
  18. Henrion MY. bootComb—an R package to derive confidence intervals for combinations of independent parameter estimates [Internet]. Int J Epidemiol. 2021 Aug;50(4):1071–6. Available from: https://academic.oup.com/ije/article/50/4/1071/6278063 https://doi.org/10.1093/ije/dyab049
  19. R Core Team. R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. [Internet]. 2020 [cited 2020 Dec 17]. Available from: https://www.r-project.org/
  20. Canton of Zurich. Numbers and Facts on COVID-19 [Kanton Zürich. Zahlen & Fakten zu COVID-19] [Internet]. [cited 2021 Jul 14]. Available from: https://www.zh.ch/de/gesundheit/coronavirus/zahlen-fakten-covid-19.html?keyword=covid19#/home
  21. Ulyte A, Radtke T, Abela IA, Haile SR, Ammann P, Berger C, et al. Evolution of SARS-CoV-2 seroprevalence and clusters in school children from June 2020 to April 2021: prospective cohort study Ciao Corona [Internet]. Swiss Med Wkly. 2021 Nov;151(45–46):w30092. Available from: https://smw.ch/article/doi/smw.2021.w30092
  22. Madewell ZJ, Yang Y, Longini IM Jr, Halloran ME, Dean NE. Household Transmission of SARS-CoV-2: A Systematic Review and Meta-analysis [Internet]. JAMA Netw Open. 2020 Dec;3(12):e2031756. [cited 2020 Dec 23] Available from: https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2774102 https://doi.org/10.1001/jamanetworkopen.2020.31756
  23. Macartney K, Quinn HE, Pillsbury AJ, Koirala A, Deng L, Winkler N, et al. Transmission of SARS-CoV-2 in Australian educational settings: a prospective cohort study. Lancet Child Adolesc Heal [Internet]. 2020 Aug [cited 2020 Aug 30];4(11):807–16. Available from: www.thelancet.com/child-adolescent
  24. Dan JM, Mateus J, Kato Y, Hastie KM, Yu ED, Faliti CE, et al. Immunological memory to SARS-CoV-2 assessed for up to 8 months after infection. Science (80-) [Internet]. 2021 Feb 5;371(6529). Available from: https://doi.org/https://doi.org/10.1126/science.abf4063

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