Article Text

Original research
SARS-CoV-2 seroprevalence among Vancouver public school staff in British Columbia, Canada: a cross-sectional study
  1. David M Goldfarb1,2,
  2. Louise C Mâsse2,3,
  3. Allison W Watts4,
  4. Sarah M Hutchison2,4,
  5. Lauren Muttucomaroe2,4,
  6. Else S Bosman2,4,
  7. Vilte E Barakauskas1,2,
  8. Alexandra Choi5,
  9. Nalin Dhillon5,
  10. Michael A Irvine6,7,
  11. Frederic Reicherz2,4,
  12. Collette O’Reilly8,
  13. Sadaf Sediqi2,
  14. Rui Yang Xu2,4,
  15. Hamid R Razzaghian2,4,
  16. Manish Sadarangani4,9,
  17. Daniel Coombs10,
  18. Sheila F O’Brien11,12,
  19. Pascal M Lavoie2,4
  1. 1Department of Pathology and Laboratory Medicine, The University of British Columbia, Vancouver, British Columbia, Canada
  2. 2British Columbia Children's Hospital Research Institute, Vancouver, British Columbia, Canada
  3. 3School of Population and Public Health, University of British Columbia, Vancouver, British Columbia, Canada
  4. 4Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada
  5. 5Office of the Medical Health Officer, Vancouver Coastal Health Authority, Vancouver, British Columbia, Canada
  6. 6British Columbia Centre for Disease Control, Vancouver, British Columbia, Canada
  7. 7Faculty of Health Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
  8. 8Vancouver School Board, Vancouver, British Columbia, Canada
  9. 9Vaccine Evaluation Center, British Columbia Children’s Hospital Research Institute, Vancouver, British Columbia, Canada
  10. 10Department of Mathematics, University of British Columbia, Vancouver, British Columbia, Canada
  11. 11Epidemiology & Surveillance, Canadian Blood Services, Ottawa, Ontario, Canada
  12. 12School of Epidemiology & Public Health, University of Ottawa, Ottawa, Ontario, Canada
  1. Correspondence to Dr Pascal M Lavoie; plavoie{at}bcchr.ca; Dr David M Goldfarb; David.Goldfarb{at}cw.bc.ca

Abstract

Objectives Few studies reported COVID-19 cases in schools during the 2020/21 academic year in a setting of uninterrupted in-person schooling. The main objective was to determine the SARS-CoV-2 seroprevalence among school staff in Vancouver public schools.

Design Cumulative incident COVID-19 cases among all students and school staff based on public health data, with an embedded cross-sectional serosurvey among a school staff sample that was compared to period, age, sex and geographical location-weighted data from blood donors.

Setting Vancouver School District (British Columbia, Canada) from kindergarten to grade 12.

Participants Active school staff enrolled from 3 February to 23 April 2021 with serology testing from 10 February to 15 May 2021.

Main outcome measures SARS-CoV-2 seroprevalence among school staff, based on spike (S)-based (unvaccinated staff) or N-based serology testing (vaccinated staff).

Results Public health data showed the cumulative incidence of COVID-19 among students attending in-person was 9.8 per 1000 students (n=47 280), and 13 per 1000 among school staff (n=7071). In a representative sample of 1689 school staff, 78.2% had classroom responsibilities, and spent a median of 17.6 hours in class per week (IQR: 5.0–25 hours). Although 21.5% (363/1686) of surveyed staff self-reported close contact with a COVID-19 case outside of their household (16.5% contacts were school-based), 5 cases likely acquired the infection at school based on viral testing. Sensitivity/Specificity-adjusted seroprevalence in 1556/1689 staff (92.1%) was 2.3% (95% CI: 1.6% to 3.2%), comparable to a sex, age, date and residency area-weighted seroprevalence of 2.6% (95% CI: 2.2% to 3.1%) among 5417 blood donors.

Conclusion Seroprevalence among staff was comparable to a reference group of blood donors from the same community. These data show that in-person schooling could be safely maintained during the 2020/21 school year with mitigation measures, in a large school district in Vancouver, Canada.

  • COVID-19
  • public health
  • paediatrics
  • epidemiology

Data availability statement

Data may be obtained from a third party and are not publicly available. Data may be obtained by making a written request to the COVID-19 Immunity Task Force.

http://creativecommons.org/licenses/by-nc/4.0/

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.

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Data availability statement

Data may be obtained from a third party and are not publicly available. Data may be obtained by making a written request to the COVID-19 Immunity Task Force.

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Footnotes

  • Twitter @DaveMGoldfarb, @Pascal_M_Lavoie

  • Contributors LCM and PML obtained funding for this study; DMG, AWW, SMH, MAI, DC, PML and LCM designed the original study concept; SMH further contributed to data interpretation; FR reviewed the literature; ESB constructed and managed the data collection database; LM set-up and coordinated the recruitment of participants; SS and HRR processed blood samples, under the supervision of VEB; ND analysed the population-level data from students and school staff, under the supervision of AC; MAI performed statistical analyses; SFO'B provided and analysed matched data from Canadian blood donors; AWW performed all other data analyses; CO'R facilitated communications within the District during the study; RYX helped with data analysis; MS contributed to the design of the study; DMG and PML drafted the first manuscript with specific sections written by AWW, SMH, VEB, MAI, AC, CO'R and LCM. All authors revised the manuscript and approved its final version. LM and PML accept full responsibility for the work and/or the conduct of the study, AW, LM and PML had access to the data, and DMG, LM and PML controlled the decision to publish.

  • Funding The study was funded by the Government of Canada via its COVID-19 Immunity Task Force (to PML and LCM as co-principal applicant; award # AWD-016994). PML and LCM receive a salary from the British Columbia Children’s Hospital (BCCH) Foundation through the Investigator Grant Award Program (award number is not applicable). MS is supported via salary awards from the BC Children’s Hospital Foundation, the Canadian Child Health Clinician Scientist Program and the Michael Smith Foundation for Health Research (award number is not applicable). The BC Children’s Hospital Healthy Starts Theme provided some seed funding at the beginning of the study (award number is not applicable).

  • Map disclaimer The inclusion of any map (including the depiction of any boundaries therein), or of any geographic or locational reference, does not imply the expression of any opinion whatsoever on the part of BMJ concerning the legal status of any country, territory, jurisdiction or area or of its authorities. Any such expression remains solely that of the relevant source and is not endorsed by BMJ. Maps are provided without any warranty of any kind, either express or implied.

  • Competing interests CO'R is an employee of the Vancouver School District, but the District was not involved in the design, analysis, interpretation of the data or the drafting of this manuscript; MS has been an investigator on projects funded by GlaxoSmithKline, Merck, Pfizer, Sanofi-Pasteur, Seqirus, Symvivo and VBI Vaccines. All funds have been paid to his institute, and he has not received any personal payments; the authors declare no relevant conflicts of interest. LifeLabs and Dynacare played no role in the study other than providing a service for the collection of blood samples.

  • Patient and public involvement Patients and/or the public were involved in the design, or conduct, or reporting, or dissemination plans of this research. Refer to the 'Materials and methods' section for further details.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.