COVID-19: Return to normal depends on immunity, say pushers for new blood tests


TORONTO – Pressure to start measuring COVID-19 immunity is increasing, with several provinces hinting at plans to set up blood tests that could pave the way for a return to a semblance of normal daily life .

So-called serological tests measure the amount of antibodies that appear in the blood after someone has fought an infection – including those who don’t even know they had COVID-19 because they didn’t fill up test criteria, did not seek care, or had mild or no symptoms.

These data are important to decision makers when deciding when to ease restrictions, says epidemiologist Patrick Saunders-Hastings, director of life sciences and environmental health at Gevity Consulting Inc.

Without this, our picture of the spread of COVID-19 in Canada remains incomplete – the laboratory diagnostic tests currently in use focus mainly on high-risk groups and capture only people actively infected with the virus.

“This is where the serological tests come in,” says Saunders-Hastings.

“We simply cannot – and we will not – obtain these figures from traditional laboratory tests.”

There are indications that the provinces are impatient to begin a new phase of detection, including the ongoing work of the BC Center for Disease Control to develop a test with the National Microbiology Lab.

British Columbia provincial health worker Dr. Bonnie Henry said Thursday by email that a serological test “should hopefully be online in ten days.”

Meanwhile, the Alberta medical officer of health said his province will almost triple the daily tests over the next month, in part by adding an unapproved blood test that reveals who in the community has been exposed to COVID- 19.

“Ultimately, our test goal by mid-late to late May would be around 20,000 tests per day. It would be a combination of swab tests as well as serology – blood tests, “said Dr. Deena Hinshaw earlier this week.

An Alberta Health spokesperson added that the province’s public health laboratory is also working with the National Microbiology Lab to validate several serological tests, which would only be used to determine a past infection, not the current one.

Saskatchewan’s chief medical officer of health said his province has also partnered with the Public Health Agency of Canada to investigate serological tests.

Dr Saqib Shahab predicted on Saturday that a serological test “will be available in the coming weeks”.

“Over time, it will be essential for us to know: How widespread is COVID 19? Which age groups have the most impact? What age groups and which populations enhance the strong immune response? ” he said.

Of course, the other big question he can help answer is: when can we lift physical distancing measures?

In other words, a return to normal depends on the discovery of the greatest possible number of active and resolved cases of COVID-19.

Those who are immune can help those who are vulnerable because they will not unknowingly transmit the virus, says Saunders-Hastings. They could also return to work.

Estimates of the proportion of asymptomatic infections vary widely, but he says most experts believe it is between a quarter and a half of all cases.

This suggests that there may be a significant number of undiagnosed immune individuals already able to return to work safely, or to assume more of the burden of primary care involving communities and individuals. high risk.

For this reason, effective serologic tests should not be bound by the same restrictive criteria used to perform diagnostic DNA testing, says Dr. Camille Lemieux, chief of family medicine at the University Health Network in Toronto.

DNA testing is targeted to isolate cases and limit the spread of COVID-19, but serological testing looks for past infections missed or excluded by DNA testing, which means casting a wide net.

“We need to look more broadly at who has immunity,” says Lemieux.

“How many people got it who weren’t really sick and who weren’t tested because they weren’t qualified or because they weren’t sick enough?” These are the people we have to find and say, “What percentage of those are immune? ‘»

Among those awaiting launch is a chief financial officer for a company in Markham, Ontario, whose test is awaiting approval from Health Canada.

Mitchell Pittaway of BTNX Inc., says his test is already in use by some US labs and is being evaluated in Europe.

“By comparison, it is certainly slower,” he said of the Health Canada approval process, but said “they understand the urgency here.”

“They definitely adopt this approach which is perhaps more structured than what we have found with the FDA or in Europe. “

If approved, the 15-minute test would be administered by hospitals or clinics, not by average Canadians at home, says Pittaway.

He says it is 97% accurate compared to laboratory PCR methods, but is intended to be used in conjunction with a laboratory test to exclude the possibility that a person is still infected with the virus and could infect other people.

The results should also be interpreted by a doctor or other healthcare professional to definitively rule out the current infection, he adds.

Pittaway says he has been told that approval from Health Canada depends in part on the development of a “national strategy”.

A coordinated coast-to-coast approach is what Ms. Lemieux would like to see, and she urges policy makers to develop this as soon as possible.

“Now is the time to come up with this plan, not in two months when he says,” Oh my God, now we are over the top, let’s think about our plan now. “We have to be proactive,” says Lemieux, who also urges Health Canada to speed up the approval process for new tests.

“I really, really want to see the Public Health Agency of Canada develop a plan, like a clear plan. And then the provinces can learn from it. “

This report from The Canadian Press was first published on April 17, 2020.

Cassandra Szklarski, The Canadian Press


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