Experts say Canada needs to develop a robust system to detect COVID-19 activity in the absence of large-scale PCR testing.
Since the arrival of the Omicron variant, provinces and territories have reduced access to PCR testing, citing lack of capacity to meet demand and the need to free up healthcare resources.
Many people have since relied on the results of rapid antigen tests, but these are not as reliable at detecting the Omicron variant and their results are not tracked and reported in the way that PCR tests are. Experts say there needs to be a better way to let people know about COVID-19 activity in their community.
Caroline Colijn, a mathematician and epidemiologist at Simon Fraser University, believes there were currently “too many infections” in Canada to expand access to PCR testing to everyone to find out the true number of infections.
She said more robust programs could also be used to detect other types of respiratory infections.
“And I suspect that these are being developed, but until they are developed, deployed and the results are made public, people will find it difficult to determine what their risks are in their social group. , in their community and in their workplace,” she noted.
“They will therefore have difficulty accessing the information needed to inform their own choices, workplace policies or community policies. »
Wastewater analysis
Ms. Colijn pointed out that wastewater data is a very important source of information that can be shared publicly without compromising anyone’s private medical data and can help communities understand the prevalence of COVID-19. But like PCR and rapid tests, this method has its limitations, she said.
She noted that there are many factors that could alter sewage signals, such as rainfall, temperature, and different variants leaving different amounts of genetic material in the water, resulting in fewer COVID-19 case estimates. precise.
Ms Colijn expects to see an integrated system that would incorporate sewage data, but also PCR and rapid test results, so as to paint a more accurate picture of the amount of COVID-19 infections in a population and thus inform people of the risk of contracting the virus.
“So we need to think about how to get representative samples and understand how many infections there are,” she said.
Dr. Dan Gregson, an infectious disease physician and medical microbiologist at the University of Calgary, said it would be reasonable to expand access to PCR testing to certain settings like schools and long-term care homes. in the event of an outbreak so that they can make the decision to close classes or reinforce sanitary measures in these establishments to prevent further transmission.
He pointed out, however, that the average person can use sewage data to assess the risk of contracting COVID-19 in their community because it’s more cost-effective and “gives us similar information” to PCR test results.
It would probably not be possible to expand access to PCR testing again to all symptomatic people on a sustainable basis, due to the high cost of testing, according to Dr. Peter Juni, Scientific Director of the Scientific Advisory Table on Ontario COVID-19.
Dr. Juni noted that when PCR testing was available to all Ontario residents, only between 30 and 45 per cent of infections were detected because not everyone with the virus was tested. Some might be asymptomatic, while others might not have time to get tested, and still others might not have been tested soon enough.
As for the rapid antigen tests available in Canada, he said they have shown “lower screening performance” in detecting the Omicron variant.
What’s needed is a COVID-19 detection system that can use a random sample in a population “to try to understand what’s really going on and what can be scaled up if necessary,” the panel argued. Dr Juni.
This article was produced with the financial support of the Meta Fellowships and The Canadian Press for News.