About 45% of people affected by the onset of longer-term symptoms say they have been hospitalized, at one time or another, because of COVID-19. This proportion is significantly lower for people who report having had mild (7%) or rather moderate (17%) symptoms. More than a third of those who have experienced severe symptoms (37.8%) say they are dealing with long COVID, however.

In the longer term, vaccination also has a clear impact on the development of symptoms. The evidence: About 12% of people who received three doses of the vaccine said they had symptoms three months after infection, compared to about 25% in adults who had not been vaccinated before contracting the virus. That said, “it should not be assumed that the relationship between vaccine doses received prior to infection and longer-term symptoms will hold in the future due to the possibility of waning immunity,” says PHAC. “Vaccination helps prevent long COVID, that we know,” says Alain Lamarre, professor and researcher specializing in immunology and virology at the National Institute for Scientific Research (INRS). “It’s actually one of the only things that seems to be working well for treatment right now. »

First, Prince Edward Island has the most people reported to have “experienced longer-term symptoms after testing positive for COVID-19”. 19”, with almost 25%. It is in Quebec that the number of people with symptoms of what could be similar to long COVID is the lowest, with barely 14%. Further west, this number exceeds 21% in Alberta and 20% in Saskatchewan, in particular. Nationally, the Canadian average is about 17.2%.

The percentage of adults having to deal with long-term COVID is also much higher among the chronically ill. About 47% of Canadians with four or more chronic conditions live with prolonged symptoms of COVID-19, compared to only 12.8% of adults without chronic conditions. The examination of the various chronic diseases must nevertheless “be interpreted with caution, as comorbidities can also contribute to the appearance of symptoms in the longer term”, underline the experts in their report.

It appears that sex reported at birth is also “significant” in the onset of longer-term coronavirus symptoms, says the Public Health Agency of Canada. About 22% of women reported having symptoms three months after a diagnosis, compared to 12.5% ​​of men. “No statistically significant association” was however detected by the researchers with regard to age group, level of education or even sexual orientation. “Ethnicity and socio-economic factors will be explored in greater depth in future publications,” the organization further explains.

According to Alain Lamarre, the scientific knowledge around the long COVID remains despite everything very nebulous. “It is not yet understood what the risk factors are, so why some people are affected and not others. We also don’t yet know the factors that would make us susceptible to developing long-lasting COVID,” he explains. In addition, continues the expert, this form of prolonged disease “has several clinical manifestations”. “The portrait is very different from person to person. There are people for whom it is really more neurological, while for others it is respiratory or muscular. It’s difficult to explain and it makes it difficult to have a mechanism that will unify all these symptoms, ”insists Mr. Lamarre.