This is a summary, written by members of the CITF Secretariat, of

Watts AW, Mâsse LC, Goldfarb DM, Irvine MA, Hutchison SE, Muttucomaroe L, Poon B, Barakauskas VE, O’Reilly C, Bosman ES, Reicherz F, Coombs D, Pitblado M, O’Brien SF, Lavoie PM. SARS-CoV-2 seroprevalence among public school staff in Metro Vancouver after the first Omicron wave in British Columbia, Canada. medRxiv 2022.07.04.22277230; doi: https://www.medrxiv.org/content/10.1101/2022.07.04.22277230v1.

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

A preprint, not yet peer-reviewed, from a CITF-funded study, suggests that the chances of adults getting infected with SARS-CoV-2 was lower in the school setting than it was in the community, even during the first Omicron wave. The research out of British Columbia, led by Dr. Pascal Lavoie and Louise Mâsse of the University of British Columbia, shows that notwithstanding frequent exposures to COVID-19, the prevalence of SARS-CoV-2 infections among the staff of three main school districts in the greater Vancouver area was not statistically greater than a reference group of blood donors from the same community (26.5% vs 32.4%).

Key findings

  • A majority (65.8%) of the school staff reported close contact with a COVID-19 case outside the household during the pandemic:
    • For 51.5% of them, the close contact was at school with a student;
    • For 54.9% of them, it was at school with a co-worker;
    • However, 52.2% of school staff reported no-close contact with a school case.
  • Of the 1,620 school staffers who underwent serology testing, 381 (23.5%) were positive for infection-acquired antibodies (anti-nucleocapsid antibodies). Of those who tested positive, 272 (71.4%) suspected that they had had a prior COVID-19 infection, and 194 (50.9%) reported a previous positive viral test.

Data were collected from staff working in the Vancouver, Richmond and Delta school districts. Samples were first collected between February and June 2021, and again between January and April 2022 (shortly after the first Omicron wave struck BC) (N=1845). Of these participants, 15.8% self-reported a positive COVID-19 either by RT-PCR or by rapid antigen test, while 16.3% reported having symptoms of COVID-19.

With respect to all school staff, and not just those who participated in the serological testing, 81% were classroom workers with a median contact time of 18 hours per week with students. Almost all staff (99%) had received at least two doses of vaccine. About one-third of school staffers reported living with an essential worker, 41% had children and 21% reported having had a COVID-19 case in the household.

Comparative community data were obtained from Canadian blood donors between January 1 and March 31, 2022 (N= 7164), in a study lead by Sheila O’Brien from Canadian Blood Services.

This study confirmed that a substantial proportion (26.5%) of school staff showed evidence of a SARS-CoV-2 infection during the first Omicron wave in BC. However, the study identified no detectable increase in seroprevalence compared to a reference group of blood donors from the same age, sex and residency area.