Dr. Timothy Evans, director of the School of population medicine and of global health at McGill University, who is also the executive director of the national working group on immunity in the face of the COVID-19.
July 5, 2020 10: 32
Updated at 17h16
Infected people: a first preview in mid-July?
The Canadian Press
OTTAWA — The national working Group on immunity in the face of the COVID-19 has begun to test thousands of blood samples to detect the presence of antibodies. He should be able to produce a more detailed picture of the number of Canadians infected by the new coronavirus in a few weeks.
However, it will take a lot more time before you learn more about the type of protection provided by antibodies against a new infection, warns Dr. Timothy Evans, executive director of the working group.
In addition, most of the people whose blood is tested will not be notified of the results in because of the way the blood is collected for testing, ” he adds.
“The individuals will not have the opportunity to know their status,” said Dr. Evans, who is also the director of the School of population medicine and of global health at McGill University.
More than 105,000 Canadians were declared positive at the COVID-19 since the beginning of the pandemic. Many others have been sick, but could not be tested because the provinces had limits until a few weeks ago.
Dr. Evans reminds us that a significant number of people affected are asymptomatic and have no idea that they have already been sick. It mentions that the immunity tests carried out in other countries suggest that the rate of real infection is 10 to 20 times higher than the number of confirmed cases.
The plan of the working group has several components to determine the true infection rates in the country. Dr. Evans noted that up to 1600 blood samples are tested daily. The researchers are looking for signs that a patient has antibodies from a past infection.
The first tests were carried out on 40 000 samples collected from people who donated blood to the canadian blood services or Héma-Québec since may.
“I hope that in the next two weeks, we will have a first digit”, he said.
The first results will reveal the number of the samples showed antibodies, but will not include any specificity as to the type of the tested individuals or their geographical distribution.
“By the end of the month of July, we expect to have a more detailed picture of what we call the seroprevalence, the presence of antibodies in the blood, by age group and by geography,” notes Dr. Evans.
The executive director of the working group mentioned that canadian blood services can not trace back the samples up to the patients who have given. We will not be able to prevent those who have antibodies. He adds that Héma Québec has indicated that it might be possible to do so, but nothing has been decided about it.
Another testing program is starting on 25 000 samples of blood taken from pregnant women. The researchers will use blood collected regularly during the first trimester of pregnancy to screen for sexually transmitted infections, and testing for immunity against other diseases such as rubella. The screening tests for antibodies of the COVID-19 will be added to this list for all pregnant women in Canada, up until December. Women will be informed if their test is positive, ” says Dr. Evans.
Evans adds that there are also about 30 000 blood samples held in the provincial laboratories, which are tested for the antibody.
The tests that the working group uses require only a small amount of blood — less than one-twentieth of a teaspoon, in general, but it is always more than what comes from a finger prick.
Dr. Evans argues that the understanding of the number of infected people can help to guide policy-making on the location of the first vaccination. We can also determine the effect that specific measures of public health may have trained in some contexts, such as the centres long-term care, hospitals, and schools.
The working group also has a term of two years to try to see what type of protection provide the antibodies and their duration of life. Dr. Evans notes that these studies were only beginning and will take time, particularly to see if the people who have developed antibodies may have been infected during a second or third wave of the pandemic.