Researchers from SeroTracker followed SARS-CoV-2 testing programs reported by 1,159 Canadian and 1,081 international employers across multiple sectors from March 1, 2020, to March 31, 2021. In a recent preprint, therefore not yet peer-reviewed, they report that fewer than 20% of high transmission workplaces had publicly disclosed a testing program. These workplaces represent retail and customer-facing environments, as well as indoor and mixed blue-collar settings.

Authors drew the list of employers to include in their study from stock exchanges, curated lists that rank employers by size, and expert recommendations. The largest companies by market capitalization (dollar value based on stock markets) and sector were chosen, with a final list of 1,159 Canadian and 1,081 international employers. A Google search was set up to identify publicly available data on testing programs instituted by each employer.

As of March 31, 2021, 9.5% (n=110) of Canadian employers and 24.6% (n=266) of international employers surveyed had reported initiatives to test employees for current or past infection with SARS-CoV-2. Only 250 employers reported the type of testing used, with 174 (69.6%) using diagnostic testing (64% nucleic acid, 23% antigen, 13% both), 34 (13.6%) using antibody tests only, and 42 (16.8%) using both diagnostic and antibody tests.

When looking at results by sector, fewer than 20% of employers in retail or customer-facing settings, indoor and mixed blue-collar workplaces, or office settings reported testing, compared to over 40% of universities (42% of Canadian and 69% of international) and hospital settings (41% of Canadian and 71% of international ones).

Despite the probability of underreporting, the findings from this study highlight opportunities to further implement testing programs in high-risk workplaces to improve workplace safety.

SeroTracker is an online tool that tracks and visualizes global COVID-19 serology testing data; testing examines blood samples for antibodies that indicate a person has been exposed to the novel coronavirus or that they have received a vaccine against SARS-CoV2. To learn more about the team, their methods and data, visit their website:


Duarte N, D’Mello S, Duarte NA, Rocco S, Van Wyk J, Pillai A, Liu M, Williamson T, Arora RK. Uptake of SARS-CoV-2 workplace testing programs, March 2020 to March 2021. MedRxiv. 2021.06.29.21259730; doi: