Improving Ontario’s COVID-19 testing and screening policies
The Ontario response to COVID-19 has been both exemplary and lacking in foresight. Ontarians have shown admirable civic responsibility in following government directives to socially distance and avoid high-risk activities for the most part. Our hospitals showed remarkable ingenuity in expanding capacity. The combination of citizens’ commitment to responsible behaviour and our hospitals’ increased readiness has prevented our health-care system from being overwhelmed by the virus as occurred in other jurisdictions.
However, our approach to testing and tracing for the SARS-CoV-2 virus has been confused and poorly communicated. Ontarians have been uncertain as to who should get tested. The adequacy of public health contact tracing after a positive test is concerning.
The prolonged course of the pandemic in Ontario may be related to undiagnosed and possibly asymptomatic infected people in the community spreading the virus.
As we move into the next phase of pandemic management, it is crucial that we change our strategy from testing for obvious infection to screening larger populations for asymptomatic disease that can result in quiet outbreaks. This is essential for reopening our economy and schools since new waves of COVID infection must be contained at an early stage before needing to again shut down Ontario.
In order to protect our workplaces and schools against asymptomatic spread, we need to look at the recent example in Wuhan, China, where more than six million people were tested for infection in nine days.
These numbers seem unbelievable in Ontario, where we are struggling to do 20,000 tests in a day. However, this number of tests from Wuhan (more than 30 times our current target) would be achievable if we were to change three aspects of our current testing strategy to create a COVID-19 screening program that was easier and more cost-effective than our current approach.
First, we must change the way that we take specimens. The current method of using a special swab to take a specimen from the throat through the back of the nose is uncomfortable and requires a health-care professional dressed in full personal protective equipment to take the swab. The Centers for Disease Control in the U.S. has approved anterior nasal swabs and saliva samples that can be obtained by the patient under observation as a reliable method for specimen collection.
This is easier for people being tested and it would not require health-care workers to be present (video observation could be used to instruct the person in swabbing themselves) for sample collection. It would also eliminate the need for special swabs that are in short supply and reduce the use of protective equipment.
Second, we need to move to a different testing method of pooling samples rather that testing each sample individually for the genetic material used to diagnose the virus. Using a screening methodology of pooling specimens, we can substantially reduce demand for the scarce and expensive testing reagents in identifying rare asymptomatic individuals in large populations.
For example, if one person in 100 had the virus, we would take nose swabs from 100 people and pool the 100 specimens into 20 batches of five samples each while preserving all the original100 specimens. One of the 20 batches would test positive and we would then test the five samples in that batch to identify the one positive person. Twenty-five tests would be used to find the asymptomatic positive individual rather than the 100 tests we would do today. This batching method was used in Wuhan to identify about 200 positive cases in the more than six million specimens screened.
Finally, we must accept the fact that screening for COVID-19 is going to be a cost of doing business in Ontario until extensive vaccination against the virus is accomplished. Our publicly funded health system should not be expected to screen workers in factories, farms and entertainment facilities on a regular basis. This testing should be organized at work with companies offering regular testing as part of keeping their workplace safe.
This virus will be with us for at least the next year and asymptomatic transmission is recognized as an important aspect of spread. If we are going to identify the “needle in the haystack” asymptomatic individual who can cause an outbreak, a cost-effective screening program for COVID-19 must be adopted.