This Briefing Note was completed by the Research, Analysis, and Evaluation Branch (Ministry of Health) based on information provided by members of the COVID-19 Evidence Synthesis Network. Please refer to the Methods section for further information.

Purpose

This note provides a summary of evidence sources and jurisdictional experiences on testing for COVID-19, including symptomatic and asymptomatic testing. It addresses the following questions: 1) who should be tested and with what frequency; 2) where should testing take place; 3) what part of the health system should lead the testing; 4) what is the rationale for testing decisions; 5) what approaches directly complement testing strategies; and 6) what are the testing capacities of non-Canadian jurisdictions. Information is also provided on the availability, accuracy, guidelines, benefits, and limitations of point-of-care diagnostic tests in Canada.

*The full version of the Briefing Note including Supporting Evidence and the Appendix can be accessed in the PDF file at the top of the page*

Key Findings

• Guidelines recommend testing for symptomatic people based on the likelihood of contracting the infection or testing that targets specific groups (e.g., home care patients recovering from COVID-19 prior to being released from home isolation, admissions to long-term care facilities, mass or population-wide testing).
  • Asymptomatic testing: Not widely used due to risks of false negative results, and uncertainty regarding the true prevalence of asymptomatic cases.
  • Antibody tests: Antibody tests conducted one week after first symptoms only detected 30% of people who had COVID-19. Accuracy increased in week two with 70% detected and was highest in week three with more than 90% detected.
• Best practices for COVID-19 testing include:
  • Frequency of Testing: A minimum of two negative tests at least 24-hours apart prior to release after being in isolation.
  • Location of Testing: Expanded testing capacity, accessibility, and reducing hospital traffic in the community through developments such as drive-in testing facilities.
  • Health System Lead: Health system testing leads are variable and can include primary care, long-term care homes, or a central agency.
  • Rationale for Testing: Strategies for making decisions about testing include: 1) clinical and epidemiological factors; 2) prioritizing testing based on transmission scenarios (e.g., clusters of cases or community transmission); and 3) establish a priority system based on the availability of tests.
  • Complement to Testing: Contact tracing, self isolation, and leveraging data (e.g., from mobile phones).
  • Testing capacity: Viral testing capacities vary: 700,000 per week in France; 157,150 per day in Germany; 12,500 per day in New Zealand, and 662 swabs per 1,000 population in Italy.

Analysis for Ontario:

• Ontario is prioritizing COVID-19 testing for: 1) those who have been in contact with a positive COVID-19 case; 2) new hospital admissions; 3) patients being transferred from hospital to home or other health care facilities; and 4) health care providers. Ontario has expanded testing to include asymptomatic persons who request a test or are referred by a physician or nurse practitioner.