At least 40 per cent of Canadians have been infected with the Omicron variant of COVID-19, according to new research compiled by Canada’s COVID-19 Immunity Task Force.
But despite this “Omicron tsunami” in Canada, as the task force experts call it, emerging data sample Not everyone who gets sick with COVID-19 will develop immunity to the infection.
In fact, one in eight people who get the virus do not develop antibodies in their blood because of their illness. And children are half as likely to develop immunity to an infection, according to data published in June.
“So forget going to some kind of ‘COVID party,'” said Dr. Catherine Hankins, a professor at McGill University School of Medicine and co-chair of Canada’s COVID-19 Immunity Task Force.
“Infection is not a viable strategy to achieve or maintain immunity.”
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This is just one of many findings from research studies funded by the COVID-19 Immunity Task Force that offer new insights into the virus that has caused a global pandemic, including how the virus is evolving and how this it is affecting the immunity provided by vaccines and infections.
The task force, made up of scientists and experts from universities and hospitals across the country, was created in April 2020 by the federal government. Its mandate is to determine the extent of COVID-19 infection in Canada, learn how the infection affects immunity, and provide information to governments and decision-makers about the virus, based on data and research.
One thing that has become clear in recent months is that Omicron and its sub-variants have developed a formidable ability to evade immunity, whether from vaccinations or previous infections, according to data released by the task force.
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Therefore, people who have contracted COVID-19 should not assume that they are now immune.
“We have one in eight people who don’t show any antibodies in their blood, so they don’t respond to the vaccine. And if they do get infected, we don’t see evidence of it… So we don’t really know what’s going on,” Hankins said.
That is why it is important for Canadians to understand that COVID-19 has not disappeared and that it is mutating and reinfecting people, he added.
There is also new data showing that people who contracted the virus before receiving their first COVID-19 vaccines ended up with the greatest protection against the virus, according to research by a team led by Michael Grant, professor of immunology and dean biomedical associate science at Memorial University.
This is what is known as “hybrid immunity”.
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Their study, which began in June 2020, looked at patients who had been infected with the original strain of the virus before being vaccinated and compared their immune response to those who received the vaccines but did not get sick.
“We saw that people who had been previously infected and then received the vaccine had a vastly more powerful immune response to the vaccine,” he said.
“So much so, that after the first injection of the vaccine, they had higher levels of antibodies than naïve people (who had not gotten sick) after two injections of the vaccine.”
Grant’s team also found that among patients who contracted earlier strains of the virus, such as the parent strain or the Delta variant, the more severe their infection, the stronger their immune response, and vice versa. This means that those who got the sickest received the most protection against the virus after they recovered.
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But the same is not true for Omicron and its sub-variants, Grant said.
If an individual develops antibodies as a result of an Omicron infection, the levels of immunity provided by that disease are quite low, leaving them vulnerable to future or repeated infections.
“There is a general consensus that two injections and then infection with Omicron is about as good as getting three injections of a vaccine,” Grant said.
“But because it’s a milder infection, either because people have been vaccinated or because the virus is less virulent, it doesn’t seem to stimulate as strong an immune response as previous infections did.”
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In general, although current COVID-19 vaccines do not prevent transmission of new strains of the virus, there is strong scientific evidence that the vaccine prevents serious illness and death.
The challenge for health officials going forward will be to ensure that the public is aware of this and that people stay up to date on their vaccinations. Research funded and compiled by the task force to date shows that immunity to COVID-19 declines over time, Hankins said.
“I think it’s important for people to understand that if you’ve had it before, you’re still an easy target for these new variants, that they don’t pay attention to the fact that you’ve had it before, and if your immunization is expired, you don’t have the immunity that he was closest to when he got his vaccine,” he said.
“So it’s really important to get that reinforcement.”
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