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.
Supporting Evidence
*The entirety of the Supporting Evidence section can be accessed in the PDF file located at the top of the page*
This section summarizes key findings on COVID-19 testing from relevant evidence documents, as well as testing experiences in Canadian provinces and territories and other countries. Additional details are provided in the Appendix.
The Supporting Evidence tables in the PDF file provide information on the following questions:
1. Who should be tested and frequency of testing?
2. Where should individuals be tested?
3. What part of the health system should lead testing?
4. What is the rationale for testing decisions?
5. What approaches directly complement testing?
6. What are the testing capacities of non-Canadian jurisdictions?
Methods
The COVID-19 Evidence Synthesis Network is comprised of groups specializing in evidence synthesis and knowledge translation. The group has committed to provide their expertise to provide high-quality, relevant, and timely synthesized research evidence about COVID-19 to inform decision makers. The following members of the Network provided evidence synthesis products that were used to develop this Evidence Synthesis Briefing Note:
- Wilson MG, Waddell K, Gauvin FP, Mansilla C, Moat KA, Wang Q, Voorheis P, Bhuiya AR, Ahmad A, Lavis JN. COVID-19 rapid evidence profile #12: What insights from the available evidence and jurisdictional scans can inform who should be tested for COVID-19 and how frequently, where, by whom and with what follow-up actions they should be tested? Hamilton: McMaster Health Forum, 2 June 2020.
- Abou-Setta AM, Okoli G, Lam O, Kasireddy V, Askin N, MacKenzie L, Straus SE, Tricco AC. Testing for asymptomatic COVID-19: A rapid systematic review and jurisdictional/healthcare organizational scan. (Draft). June 2, 2020.
- Kelly SH, and Wells GA. Rapid and Point-of-Care Diagnostic Tests for SARS-CoV-2 (COVID-19): A Rapid Summary of Tests available in Canada. June 3, 2020.
- Bhatia, D., Morales-Vazquez, M., Song, K., Roerig, M., Allin, S., & Marchildon, G. (May 2020). COVID-19 Case and Contact Tracing: Policy Learning from International Comparisons. Toronto: North American Observatory on Health Systems and Policies. Rapid Review (No. 30).
- Waddell K, Wilson MG Gauvin FP, Mansilla C, Moat KA, Wang Q, Lavis JN. COVID-19 rapid query response #1: What are large non-Canadian jurisdictions’ planned daily (viral and antibody) testing capacity by the fall? Hamilton: McMaster Health Forum, 10 June 2020.
- Deeks, J.J., Dinnes,J., Takwoingi,Y., Davenport,C., Spijker,R., Taylor-Phillips,S., Adriano,A., Beese,S., Dretzke,J., Ferrante di Ruffano,L., Harris,I.M., Price,M.J., Dittrich,S., Emperador,D., Hoo, L., Leeflang,M.M.G., Van den Bruel,A.. Antibody Tests for Identification of Current and Past Infection with SARS-CoV-2. Cochrane Database of Systematic Reviews 2020, Issue 6. Art. No.: CD013652.