What are the different tests available to detect COVID-19, and how do they compare in terms of accuracy? How are the results reported back to the public and in what detail?

This guidance states that the use of point-of-care tests can be simpler to use and can facilitate faster test results. These tests are to be used in doctor’s offices, pharmacies or at the bedside. As of September 30, 2020, three point-of-care tests for SARS-CoV-2 were available in Canada.  

This guidance describes that PCR-based testing detects COVID-19 virus genetic material (RNA). In Canada, a variety of different PCR-based tests are available, although a nose or throat swab is most typical. PCR-based testing is used to diagnose active COVID-19 cases and therefore facilitate case identification, isolation, treatment and contact tracing. Serologic tests measure the level of antibodies of COVID-19 in a person’s blood. Antibodies are the proteins produced by the immune system to protect your body from infection and are not present until later in the course of an infection. Serologic tests can show who has been exposed to COVID-19. 

This guidance states that there are 3 types of tests available for COVID-19. A real-time polymerase chain reaction (RT-PCR) test that detects virus’s genetic material, an antigen test that detects specific proteins on the surface of the virus, and an antibody test that looks for antibodies that are made by your immune system in response to a specific virus. Antigen tests usually provide the results on an active infection faster than a PCR test but have a higher chance of missing an active infection. 

This guidance states that nasopharyngeal (NP) specimens are the gold standard collection method for COVID-19 PCR testing. Combined swab or throat with anterior nares, or deep nasal specimens are recommended as alternatives to NP specimens. Saliva specimens is slightly less accurate, but still has an acceptable sensitivity, particularly within the first 7 days of symptom onset. Combined throat swab with nares, throat specimens and saliva specimens can be collected by a broader range of health professionals or can be self-administered. No single test provides 100% sensitivity, and a negative test result should be taken in context with the patient's signs, symptoms and exposure history.  

This guidance states that serologic assays detect an antibody response to COVID-19 in a given sample to determine if there is any prior exposure. This is done by detecting immunoglobulin A (IgA), IgM, IgG, and/or the gold standard in serological testing, functional humoral antibody. Both IgA and IgM are markers for early infection; antibodies are detectable from the first week of symptoms up to 32 days after. While it is known that IgG is a marker in infected individuals three weeks after the onset of symptoms it is not known how long IgG persists. Serologic assays used to detect the presence of antibodies (IgM, IgA, IgG) have varying results for sensitivity and specificity depending on the manufacturer. However, studies have inconclusive data that the presence of antibodies will result in immunity to coronavirus antigens 100% of the time. Due to the variable test performance and lack of information, serologic assays can only determine past exposure to COVID-19. 

The Government of Ontario notes that upon getting a COVID-19 test, this website uses the details such as one's health card number and date of birth for individuals to receive test results. Results can take up to four days with the following information:  1) when and where a patient was tested; 2) the patient’s results; and 3) how to proceed based on the results. If you test positive, the guidance states the individual must: 1) self-isolate immediately; 2) await a call from the local Public Health Unit within a few days; 3) create a list of places and people the individual has had contact with to help with Public Health contact tracing; and if you should request a one-time code to enter to the COVID Alert mobile app to notify contacts immediately of potential exposure through the app. 

Johns Hopkins Center for Health Security notes that the effectiveness of tests is classified by the sensitivity and specificity of the test. A test with a high sensitivity should correctly identify all truly positive cases, while a test with a high specificity should correctly identify all truly negative cases.  

This study assesses the accuracy and reliability of self-administered specimens for COVID-19. Participants were provided with an instructional video on how to provide a nasopharyngeal and oropharyngeal self-administered swab and a live demonstration. After trainings, swabbing execution was high. Training videos can be used to optimize procedural technique.