The Ontario COVID-19 Science Advisory Table is a group of scientific experts and health system leaders who evaluate and report on emerging evidence relevant to the COVID-19 pandemic, to inform Ontario's response. Our mandate is to provide weekly summaries of relevant scientific evidence for the COVID-19 Health Coordination Table of the Province of Ontario, integrating information from existing scientific tables, Ontario's universities and agencies, and the best global evidence. The Science Table summarizes its findings for the Health Coordination Table and the public in Science Briefs.

SARS-CoV-2 screen testing is routine serial testing of asymptomatic individuals outside of outbreak or known exposure settings to identify staff infectious with SARS-CoV-2 and exclude them from work. Routine asymptomatic screen testing of staff has been proposed as a potential mitigating strategy to reduce SARS-CoV-2 introduction and transmission in long-term care (LTC) homes. A rapid review of the literature found no real-world evidence to either support or refute screen testing in preventing LTC home COVID-19 outbreaks. There are several direct harms associated with screen testing, as well as opportunity costs, including exacerbating LTC staffing shortages. On the basis of the evidence reviewed, and given the high rates of protection of COVID-19 vaccines against symptomatic and asymptomatic SARS-CoV-2 infection, the potential harms and costs of screen testing among vaccinated LTC home staff likely outweigh the benefits.