People skate on a lake in a city park in Montreal, Jan. 10, 2021.Graham Hughes/The Canadian Press
Canada has been unable to get a national picture of the country’s immunity to COVID-19, despite promises from the federal government that it would conduct mass blood tests to find out how common the antibodies are.
Epidemiologists have been frustrated by the lack of movement, insisting that keeping tabs on the prevalence of these antibodies can improve public-health orders, inform vaccination plans and measure how close the country is to herd immunity. They point to the United States and Britain, which have done exactly that.
But the scientists and researchers tapped by Ottawa to collect this data insist their research is continuing, even though mass blood tests for virus immunity are not the game changer that was promised. Their current work, the COVID-19 Immunity Task Force says, will be instrumental in the coming months.
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Prime Minister Justin Trudeau announced last April that his government would fund “a series of countrywide blood test surveys” that would ensure the “rapid reporting of results” of just how many Canadians were immune from the virus. To do that, the government set up the task force of scientists and public-health officials, and housed it in McGill University.
These so-called serology tests do not indicate whether someone is currently infectious, but measure the level of antibodies in the bloodstream, which can indicate if a person previously had COVID-19 and whether they are protected from reinfection. Those results can also help reveal outbreaks that have not been captured by more ad hoc nasal swab testing campaigns.
But since the task force was announced, there have been few updates on how many Canadians are estimated to be immune from the virus.
Health Canada confirmed to The Globe and Mail that Ottawa budgeted up to $300-million, over two years, for the task force. Freedom of Information documents show it has spent or committed $70-million to date – $50-million to fund outside studies, and $20-million to set up operations and its secretariat.
From the outset, the body’s mission was difficult. Health Canada was reticent to approve serology tests, so the task force began developing its own. But that took months. The decentralized nature of Canada’s health system didn’t help, either. The task force couldn’t easily tap into provincial health systems, and instead needed to piggyback on existing partners.
More crucially, however, the researchers at McGill found that the studies were not terribly useful.
“When you put the big picture of seroprevalence together, it has not been the game changer we initially thought it would be,” said Timothy Evans, executive director of the task force and director of McGill’s School of Population and Global Health.
In the spring, the task force awarded $5-million to the Canadian Blood Services and its sister organization, Héma-Québec, to begin testing previously donated blood for evidence of COVID-19 immunity. They began testing 75,000 blood samples in May, but didn’t begin reporting data until months later.
In June, epidemiologist and University of Toronto professor David Fisman wrote an e-mail to Health Minister Patty Hajdu and warned: “We do not have a means of properly understanding the regional epidemiology of COVID-19 without seroepidemiology.” Echoing concerns raised by other doctors and public-health experts, Dr. Fisman also said provinces where rates of antibodies in the population were low would be “dry tinder in the autumn.”
When the first results from the blood donor agencies were finally released, in August, they showed that less than 1 per cent of samples outside of Quebec had the antibodies, while around 2 per cent inside Quebec tested positive.
Dr. Evans said those reports were a “clarion” that Canada was “massively vulnerable to a second wave.” The level of antibodies found was unexpectedly low.
At the same time, he said, the data didn’t tell the task force much that it didn’t already know. Concluding the pair of studies were “not a good use of taxpayer money,” the task force scaled them back.
Dr. Fisman said the lack of data going into the fall was frustrating. He said Canada ought to have been doing random, national, broad-based serological testing consistently, in hopes of offering a broader portrait of the epidemic – particularly outbreaks swab testing may have missed. “It’s your way of seeing the rest of the rest of the iceberg,” he said.
Other countries have done that. The United States has conducted 15 million serology tests, and has been reporting seroprevalence estimates by state since July. These studies revealed, for example, that about one in five New York City residents tested positive for antibodies by the summer, and have been a crucial piece of the puzzle for a country that saw huge backlogs and issues around testing.
Britain, Germany, Spain and a host of others have also conducted wide-scale serology testing.
To date, Canada has conducted about 350,000 antibody tests. The task force told The Globe it has funded 22 studies in hospitals, labs and universities across the country. But most studies are not expected to begin reporting data until this spring.
In recent weeks, the most recent data from the Canadian Blood Services and Héma-Québec began rolling in, but it seemed to confirm the task force’s hunch: The data says very little.
For example, by October, Ontario was well into the second wave of COVID-19, as case counts skyrocketed and hospitalizations climbed. Yet Canadian Blood Services’ testing showed antibody levels actually fell, and the national picture was equally perplexing.
Some of that may be a product of the nature of the study itself: Testing only among blood donors carries a significant selection bias by excluding, for example, sexually active gay men. But the task force says the numbers also confirm its decision to move away from national serology surveillance.
“One of the things that I think has become really clear, in the course of the epidemic, is that Canadian serology has not shown dramatic increases in background immunity,” said David Naylor, co-chair of the task force and former president of the University of Toronto. “It’s rising, but it’s not rising very fast.”
Instead of national surveys, the task force began funding more targeted studies through the fall, such as testing pregnant women, housing-insecure people and long-term care home residents. Those studies are well under way, but most won’t start reporting data until later this spring. Even so, they may help answer some enduring mysteries about the virus.
Catherine Hankins, co-chair of the task force alongside Dr. Naylor, said, “one of the things we discovered relatively early on … [was] the antibody levels were waning.” That, she said, could indicate that those who have recovered from the virus could be susceptible for re-infection.
The task force started investigating just what could lead to one person’s antibodies lasting for more than a year, while another person’s could fade after just a few months. To answer that question, Dr. Hankins said the task force had developed a “made-in-Canada” assay, or clinical test, that is more sensitive than the previous indicators. It can differentiate whether the body is producing antibodies because someone already caught the virus, or whether the antibodies come from a vaccine.
Serendipitously, Dr. Evans said, the task force’s testing kit for individuals was finally approved and validated in September, just as the task force was in the middle of a “strategic pivot,” he said.
The task force awarded $5-million to Statistics Canada to mail out these newly-developed test kits to 48,000 Canadians across the country. The first batch of kits, which require respondents to take a blood sample and send it to a lab for analysis, went out in November.
This survey, coupled with other regional and national studies, will tell researchers whether the vaccines are building immunity across the population. It will also, Dr. Evans hopes, beef up provincial monitoring of the vaccine rollout, helping show how effective one dose is compared with two doses, what impact new variants of the virus may have on immunity and how close Canada may be to herd immunity.
The task force hopes the data will start arriving soon. “I believe that we will be in a position in February to bring the picture into focus,” Dr. Evans said.
The senior members of the task force admit the process has been difficult. Dr. Naylor said he had considered quitting when early data appeared useless. Dr. Evans said the delays and structural barriers have been “humbling.” As his team faces the oncoming problem of trying to plug into provincial vaccination efforts, he admits the pandemic has shown “the limits of the machinery” of Canada’s health system.
But, Dr. Evans added, scientists everywhere are just trying to stay ahead of the curveballs being fired by the virus, “and it’s a good pitcher.”
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