Exactly how common it is is not clear. The tests are limited nationwide and the detailed COVID-19 data that are publicly available are also limited. “There is a lack of testing that is happening and there is some information suggesting that rapid antigen testing is not as accurate as we expected from Omicron,” said Jennifer Gommerman, a professor of immunology at the University of Toronto and Canada Research. Chair in special tissue immunity. “Prevalence is a difficult question to answer, but we know there are many viruses circulating.” PCR test scores, hospitalization data and sewage data in many provinces indicate increased virus transmission. And data from around the world show that the risk of re-infection is higher with Omicron, experts say. “When we think about this idea of re-infection, we have to consider that we are still dealing with a virus that has a unique ability to bypass these early defenses against neutralizing antibodies,” said Jason Kindrachuk, a virologist and assistant professor of medical microbiology and microbiology. at the University of Manitoba in Winnipeg. However, cases of re-infection largely do not cause worse symptoms of the disease, said Kindrachuk, who is also the Canadian Research Institute for Molecular Pathogenesis of Emerging Viruses. There are many factors for which one can become re-infected with the virus and researchers are trying to better understand re-infections and what they mean during Omicron. PCR test data in Canada is limited, so many Canadians have turned to rapid tests to see if they have COVID-19. (Jeff McIntosh / The Canadian Press)
Re-infections in global data are on the rise
Figures released by Ontario Public Health last week show that approximately 11,730 Ontarians have been re-infected with COVID-19 since November 2020. Re-infection, according to Ontario health officials, is when someone has had two laboratory-confirmed cases of SARS-CoV-2 with evidence that they were “separate infections caused by different viral generations.” South African scientists had warned in December that re-infections among humans who have already fought COVID-19 appeared to be more likely with Omicron than with previous coronavirus mutants. There has been a recent increase in re-infections in parts of the world such as the United Kingdom, which has had a similar vaccine in Canada. Prior to December 6, the rate of day-to-day cases in England considered to be re-infections was below 2 per cent for almost six months. This percentage is estimated to have increased to 9.9% in February. a Reuters analysis of UKHSA data was found. In Italy, a spokesman for the National Institutes of Health said in February that re-infection cases accounted for about 3% of all infections, up from about 1.5% before Omicron.
Why does re-infection occur?
There are many reasons why someone becomes re-infected with COVID-19, including their vaccination status and when a person was vaccinated or infected, said Dr. Lynora Saxinger, an infectious disease specialist at the University of Alberta in Alberton.
A study in Qatar published in the New England Journal of Medicine last month found that recovery from a previous infection was about 90 percent effective in preventing re-infection from the Alpha, Beta and Delta variants.
Protection against re-infection with the Omicron variant was lower at 60 percent but “still significant,” the authors said.
Another important aspect of the risk of re-infection is vaccine-induced immunity.
Experts recommend a booster vaccine to protect people better from COVID-19. (Hannah Beier / Reuters)
The strength of the immune response will depend in part on the individual’s age and overall health. Very old, very young and immunocompromised will have attenuated responses, for example.
This is why the fourth installments are now available to the most vulnerable populations across the country.
And although vaccines have repeatedly been shown to be effective in preventing serious illness and hospitalization, Omicron is still “good enough to do piercing equivalent to two doses and in many cases, two doses plus infection or three doses,” Saxinger said.
The Dose24: 11 Do I need a fourth dose of COVID-19 vaccine?
The number of COVID cases is rising once again in many parts of Canada along with hospitalizations. This week, the National Immunization Advisory Committee (NACI) proposed giving a fourth dose of COVID-19 vaccine to all Canadians age 80 and older. 24:11
Antibodies are known to fall over time after being vaccinated or infected, said Benoit Barbeau, a professor in the Department of Biological Sciences at the Université du Québec à Montréal who studies virology.
“So if you became infected in December or early January, you would already have lower levels of antibodies. It does not mean that you have completely lost your protection against the infection, but you will certainly have less protection than we say 10 days after infection.” he said.
The good news is that the immune response generated by the vaccine “is strong enough to prevent us from getting a really serious illness and ending up in the hospital,” Gomerman said.
This is why experts recommend that people take a booster vaccine for this extra protection.
With regard to the Omicron BA.2 sub-variant, early research from Denmark suggests that re-infections with this strain appear to be rare.
What do we need to know?
Barbeau said that as parts of Canada and other countries face a sixth wave, more data will emerge about who gets re-infected and why. “There will be other variants. The risk of re-infection will always be there,” he said. But he stressed that immunity in the population, whether from vaccines or from previous infection, is accumulating and allowing us to reduce transmission and hospitalization. All of this is happening as research continues to improve vaccines, whether it is adapting to new variants or researching new methods of administering vaccines such as through the nasal cavity, he said. “It’s very important that we continue to improve vaccines.”
