The rapid launch of COVID-19 testing in Canada was one of the big differences between the pandemic response here and in the United States.

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“We were screening weeks and weeks before the U.S. was,” said Craig Jenne, an assistant professor at the University of Calgary in microbiology, immunology and infectious diseases.

And Canada has led the world in its approach to testing, said Jenne, who is also a Canada Research Chair in Imaging Approaches Towards Studying Infection.

The first COVID-19 case was identified in China in mid-November. The greatest number of confirmed cases are now in the U.S., where by Thursday more than 430,000 people had tested positive for the disease and 14,800 had died.

Canada, with 10 per cent of the population of the U.S., had 18,479 confirmed cases and 461 deaths.

Jenne said that while tests for COVID-19 had to be approved by the U.S. Food and Drug Administration, in Canada each provincial health authority could develop its own test, validate that it worked and start using it. Officials shared information through the National Microbiology Lab in Winnipeg, but there was no waiting for approval from a national authority.

British Columbia and Alberta, in particular, could begin screening very early for COVID-19 as part of the screening they were already doing for influenza. “We hit the ground running a lot earlier than the U.S. did.”

B.C. was in recent weeks doing about 3,000 tests a day. Provincial health officer Dr. Bonnie Henry has said testing is now focused on those most likely to have the disease and most likely to need health or hospital care, including health-care workers and people in higher-risk environments like seniors’ homes.*

On Wednesday Henry said B.C.’s testing capacity had grown, but the number of tests being done has actually decreased as the province focuses on people who are at higher risk and the number of respiratory infections in the community has gone down.

“We will change as the epidemiology of what is happening in our community across B.C. is changing,” she said. “We do expect that our testing numbers will go up again in the near future and we’ll be looking again at making sure that we are identifying any clusters in our communities. We are still doing that, and particularly in areas of the province where there has not been a lot of community transmission, that has been the focus, but I expect will increase over the coming weeks.”

Earlier in the pandemic the B.C. testing strategy focused on travellers returning to Canada, but now they are all being ordered to self-isolate for 14 days.

The province is not testing people who may have been exposed to COVID-19 but who aren’t showing symptoms because there is a higher likelihood that the test will give a false negative result, Henry has said.

It’s an approach that has drawn criticism.

After The Tyee ran an earlier article on the B.C. strategy, a Nanaimo doctor wrote saying B.C.’s approach falls short.

“I am not able to be tested because I am asymptomatic,” he wrote. “You, like the media in general, repeat the falsehood that medical staff are tested. We are not. We can be tested only if we develop symptoms (a bit too late for patients we have infected).”

Testing is needed to understand and control the pandemic, he said. “We continue to send probable COVID positive people home from hospital without testing to self-isolate and infect their families. This is not good for them or their communities.”

He didn’t respond to a request for an interview.

Peter Phillips, the head of the infectious diseases division of the UBC Department of Medicine, has said B.C.’s restrictive testing policy “undermines the ability of public health to be successful in containing further spread in the community.” Widespread community testing would let health officials identify people with the virus and their contacts and ensure they stayed in isolation, he said.

That echoes the World Health Organization, which has said testing is one of the most important tools for accurately tracking the spread of the virus. “The most effective way to prevent infections and save lives is breaking the chains of transmission,” said WHO chief Tedros Adhanom Ghebreyesus. “And to do that, you must test and isolate.”

Jenne said he believes the approach to testing in Canada has been as good as anywhere.

“In Canada we’re seeing higher than average testing compared to other countries in the world,” he said. “Also importantly, in Canada we were very good at proactively testing rather than reactively testing.”

There are two schools of thought on testing, he said. “One is you test everybody and you get the most comprehensive picture of what’s out there, probably better data on spread.”

That approach would have advantages, but also limits, Jenne said. “Who do you test that’s asymptomatic? Everybody? Anybody who’s feeling under the weather? Well then they’re not asymptomatic,” he said. “I think it’s really problematic in that sense.”

The other school of thought, which Jenne said B.C. and Alberta are right to follow, is to recognize that the virus is already present in the community and being passed from person to person and act accordingly.

“If anyone has any symptoms or is feeling under the weather, it’s probably safe to assume they are COVID positive,” he said. “We’ve already asked everybody to socially distance. We’ve already asked everybody to stay at home, avoid work if possible in both provinces, so my view on that is the value is in testing frontline health-care workers.”

While provinces like B.C. are saying that’s what they’re doing, it’s not entirely surprising to hear stories of health-care workers not receiving tests, Jenne said. “There may be a disconnect in what’s being said and what’s actually being done at the field level.”

It’s worth keeping in mind that there will always be a lag between a person catching the virus, becoming contagious, getting tested and receiving a result, he said. “By the time you suspect you’ve been exposed and got tested, if you’re living in a house with a family, odds are they’ve already been exposed, so the whole house is required to stay self-isolated.”

And there is a danger of false negatives, especially for people who are asymptomatic, Jenne said. “If you swab somebody and they come out negative and they truly are positive, the last thing you want that person to do is believe they are negative and run around in the community.”

It makes sense to screen people who are critically ill so health-care providers know what they’re dealing with, but not people with mild symptoms or no symptoms at all, he said.

“I don’t know if there’s any further advantage in screening the general public,” he said. “Unless we’re bringing in true quarantine where every tested positive person must remain fully physically distanced from all people, I don’t know what testing changes.”

Then there’s the question of capacity. B.C. can do about 3,000 COVID-19 tests a day for a population of 5.1 million people. Even if testing is limited to the 120,000 health-care workers, it’s impossible to test them all promptly. (Alberta has varied the number of tests it does, but peaked at around 4,000 for a population of 4.4 million.)

“That’s the problem with testing,” Jenne said. “Even if by some miracle you could test everybody in the province of British Columbia in the next 48 hours, you’d have to redo that in five days. It is an evolving picture. A health-care worker who tests negative today might very well be exposed tomorrow.”

Jenne stressed that he’s a research scientist, not a practising doctor. “From a research point of view, I would love to know how many people are actually infected, and, you know, did they get symptoms or not, to better understand the virus, but there are other tests that do that.”

To understand how the disease is moving at the population level, he said there would be more value in screening the blood of a large, random sample of people for COVID-19 antibodies, something that would indicate how many people had been exposed to the virus.

Has BC Got It Right on COVID-19 Testing? read more

Officials in various countries have said that kind of testing is coming, but for now Jenne said the testing that’s being done in Canada makes sense.

“I don’t want to be crazy rosy about it, but I do think from what I’ve seen Canada really has led the world, in my opinion, in the appropriate application of [diagnostic] testing,” he said.

A lot of credit for the COVID-19 response deservedly goes to frontline health-care workers, but people working in the labs shouldn’t be forgotten, Jenne said.

“These people who are stuck in the basements of hospitals running DNA sequencers have been making personal sacrifices too to keep the provinces running.”

*Story updated on April 9 at 5 p.m. to clarify that while B.C. was doing about 3,000 tests a day in recent weeks, the number has since declined.