Health Canada authorizes serological test for COVID-19 antibodies

Health Canada says it has authorized the first COVID-19 serological test for use in the country to detect antibodies specific to the virus.

DiaSorin, an Italian multinational biotechnology company, had developed the LIAISON test that was also recently approved by the U.S. Food and Drug Administration.

In a statement Tuesday, Health Canada said it will be used in Canadian laboratories to detect COVID-19 antibodies and help contribute to a better understanding of whether people who have been infected are immune to the virus.

Health Canada says further research will also help understand the relationship between positive antibody tests and protection against reinfection.

The Canadian agency says at least one million Canadian blood samples will be collected and tested over the next two years to track the virus in the general population and in specific groups at greater risk of having been infected, including health-care workers and seniors.

Dr. Theresa Tam, Canada's chief public health officer, said it is a step toward estimating how many Canadians are infected in in various regions of the country. But she said it is premature to be able to use and interpret the results for individuals. 

"I think right now the foundations are being built," Tam said on Wednesday. 

DiaSorin's test uses intravenous blood, and the company said it can be used for up to 170 patient samples per hour. It is not a quick diagnostic test at a doctor's office with instant results.

Potential game-changer

Dr. Samir Gupta, a respirologist at St. Michael's Hospital in Toronto who isn't involved in the rollout, called antibody tests a potential game-changer.

"I think the first immediately useful information will be in the way of community surveillance," Gupta said.

Many people would have had this infection without symptoms or with minor symptoms. In some cases, they went to an assessment centre or hospital, but because there weren't enough diagnostic tests, they were told to go home and recover. Most people did, he said. 

"What we'll be able to do now is to go out and very broadly administer blood tests," Gupta said, to find out what proportion of Canada's population actually had the infection. That's useful for planning purposes.

Jennifer Gommerman is a professor of immunology at the University of Toronto who is working on trying to understand the earliest immune responses to the virus. 

Gommerman said serology tests like this one will help take into account people who've been infected but didn't develop symptoms of COVID-19. 

"We know that those people are probably a sizeable number of Canadians, and we need to get a handle on what that number is," Gommerman said.

Tania Watts, an immunology professor at U of T, said antibody tests show you've had it, but they can't tell if the virus is still in your system.

"If you get a positive test, good for you. Be happy. But I'd still be careful," Watts said. The test result can't guarantee you're protected or that you're not infectious.

Health Canada says the testing will help inform public health decisions and will expedite the supply of safe and effective health products.