A critical component in controlling the spread of this pandemic is efficient scalable testing capacities.
Health Canada has approved 34 COVID-19 tests that are primarily lab-based. Among the most common of these is polymerase chain reaction (PCR) testing that involves collecting samples from individuals’ noses or throats to determine if they are infected.
The utility of these tests is evaluated by measuring their sensitivity and specificity. Sensitivity refers to a test’s ability to recognize COVID-19 in the body to correctly produce a positive test result. Specificity refers to whether a test can properly distinguish COVID-19 from other material to generate a negative result. PCR tests are highly sensitive and can detect very small amounts of viral genetic material including dead fragments of the virus that are no longer infectious or active. However, due to their complexity, PCR tests can cost up to $150 each and may have turnaround times of up to 9 days. Consequently, they are not efficient at screening for the virus on a population scale to contain disease spread.
Alternative rapid antigen tests have been developed to supplement testing efforts. Unlike conventional tests, rapid tests are much cheaper (cost $1-$5) and have much faster turnaround times of 10-20 minutes. Such rapid tests can be used to monitor and control COVID-19 because they have high specificity in distinguishing the COVID-19 virus from other material. Despite being less sensitive than PCR tests, rapid tests are sufficiently sensitive in detecting transmissible viral loads. As stated by Dr. Michael Mina, an Assistant Professor of Epidemiology at Harvard University, the frequency of testing and speed of reporting are more important than test sensitivity when it comes to controlling the virus at this point in the pandemic.
A recent study describes viral load within an infected individual as an important factor in transmissibility. Conventional PCR testing holds an advantage in detecting individuals with lower viral loads. However, lower viral loads also indicate lower transmissibility. Therefore, rapid testing that detects transmissible viral loads would be an efficient way to augment testing efforts and has the potential to provide real-time management that may better deal with COVID-19’s speed of infectivity.
While conventional testing is often used on symptomatic or high-risk individuals, rapid testing could be used as a preliminary screening of all individuals at a population level. For example, rapid testing in schools can be implemented to escalate any necessary contact tracing efforts. In-school nurses can be trained to administer and review test results on demand, with results available within 15 minutes. Furthermore, the minimal costs would enable countries to implement rapid testing on a large scale. Rapid tests can help Canada negotiate this back-to-school season. Furthermore, rapid testing can be of great benefit in long-term care facilities where staff and visitors can be tested regularly to minimize the likelihood of future outbreaks.
Fortunately, on Sept. 1, Health Canada finally announced its willingness to consider the approval of some at-home antigen COVID-19 tests. However, with the flu season approaching, an urgent and comprehensive adaptation of rapid testing is needed. In particular, our governments should work in synergy, at all levels, to support the investment and deployment of rapid testing measures both financially and logistically. While Canada still seems reluctant to employ the use of rapid tests on a wide scale, the U.S. administration has recently purchased 150 million rapid tests from Abbott BinaxNOW. This rapid test received Emergency Use Authorization (EUA) by the Food and Drug Administration (FDA) and can be employed by any trained individual without highly specialized laboratory instrumentation. Prior to Abbott receiving approval, several rapid tests had also received FDA approval under similar provisions.
Overall, rapid antigen tests are generally an inexpensive, quick and scalable method to detect a significant portion of infectious COVID-19 viral loads. To enhance the management of viral transmission, widespread testing of individuals must be done consistently with fast turnaround time. Therefore, while PCR testing is highly sensitive, it should not be used exclusively as delays in results inhibit optimal management of disease transmission.
Health Canada has taken a step in the right direction by considering rapid tests. However, swift action and support must be undertaken in the purchase and implementation of rapid tests to prevent the impending exacerbation of this pandemic. Canada’s action toward rapid testing implementation should be expedited, most notably for the coming autumn and impending second wave. There are several options available, both local efforts in the works and others already verified by the U.S. for procurement. Ultimately, Canada must purchase and strategize the urgent deployment of rapid testing to maximize disease management.