Mailed COVID-19 antibody test gets low response rate

OTTAWA — Thousands of Manitobans have received kits from the federal government in which they are asked to prick their finger and send in a blood sample to determine whether they have antibodies for the novel coronavirus.

So far, the federal study has received less than half of the response it had projected two months ago, when the COVID-19 Immunity Task Force set out to determine how many Canadians have contracted the virus without knowing it.

“It means a bit of a hole in the data,” said Catherine Hankins, a McGill University public health professor who co-chairs the task force.

Her group wants to determine how widely COVID-19 has circulated, aside from Canadians who have tested positive for the virus. They hope to compare how long people are immune due to the vaccine versus a natural recovery from the infection.

The study involves sending 48,000 kits to homes across Canada, including 3,634 in Manitoba, in three phases. The kits include instructions, consent forms and prepaid packaging to mail the tests back.

The first phase in November involved 4,000 kits, of which 333 were sent to Manitoba.

Roughly 25 per cent of Canadians who received the kit did both the physical test and online questionnaire. A tad more than one-third of recipients did the online survey, including those who also mailed in their samples.

Statistics Canada had expected a response rate of 45 per cent.

Hankins is optimistic more Canadians will step up in the second round of testing, which has started, “especially now, when I think people will wanna to know, ‘Have I had this?’” she said Monday.

Statistics Canada has selected specific people to receive the test so it gets a range of respondents that represent the whole country, including young children whose parents are supposed to help administer the test.

Many people may have had the virus without knowing it because there have been widespread outbreaks, including during the spike in cases in the Prairies this fall and winter.

That’s why Hankins encourages Manitobans who receive the kit, to step up.

“It’s not just yourself; you are representing other people your age, your sex and your geography,” Hankins said. “You can participate by forming that complete picture, by participating in this.”

She said Statistics Canada phones recipients three times to see if they have any problems carrying out the test, including taking the responses verbally when people can’t access the website questionnaire.

It’s unclear if kits were delayed or lost in the mail during the holiday season as Canada Post dealt with a record amount of parcels being shipped due to the pandemic.

The second set of kits, amounting to roughly 1,670 in Manitoba, were sent out a week ago. About the same amount will be mailed at the end of this month.

The completed tests are sent to the National Microbiology Lab in Winnipeg to be processed. The dried-blood paper samples will be sent to another lab with identification numbers, shielding any personal information from the secondary lab.

With vaccines having just been introduced, the tests will show whether someone has antibodies from being infected, or from a vaccine, from both or neither.

All participants will be told in a confidential letter whether they have COVID-19 antibodies. Those who do will be asked if they’d agree to provide a second sample in six months, to test whether their antibodies have changed.

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