What 2 new studies reveal about long COVID in Canada | CBC News

Two new large-scale reports paint a clearer picture of the long-term impact of COVID-19 infections on Canadians and the healthcare system.

A report published on Monday by Statistics Canadafound that nearly 15 percent of people who contracted COVID-19 experienced persistent symptoms, such as fatigue, shortness of breath, or brain fog, three months or more after their initial infection.

However, compared to earlier phases of the pandemic, the report found that a much lower proportion of those infected have reported such long-term symptoms since the Omicron variant hit Canada late last year.

StatsCan, which conducted the survey in partnership with the Public Health Agency of Canada, describes it as the first nationally representative report of its kind.

A separate study was also published Monday in the Journal of the Canadian Medical Association (CMAJ) found that people who tested positive for COVID-19 in Ontario consumed more hospital and other healthcare resources than those who tested negative in the months after their infection cleared.

The reports are the latest in a growing body of research into the scope of Long COVID, a collective term for a range of post-infection health effects.

Fewer people report long COVID since Omicron: survey

The World Health Organization has estimated that what it calls the “post-COVID-19 condition” is having an impact 10 to 20 percent of those infected, but these numbers are based on earlier stages of the pandemic. Recent research suggests COVID is long now occur at a much lower rate.

StatsCan says its data suggests about 1.4 million Canadian adults — or about five percent of the general population — had symptoms three months after contracting COVID. The survey was conducted among Canadians who tested positive for COVID-19 or suspected they had the disease.

“This is a significant number of people affected by long-term COVID,” said Dr. Fahad Razak, board-certified internal medicine physician and epidemiologist at St. Michael’s Hospital in Toronto and former head of Ontario’s COVID-19 Scientific Advisory Board.

“Clinicians in the Canadian research community have been eagerly awaiting the results, and the data tells us that we are like other countries,” Razak, who was not directly involved with the study, said in an interview with CBC News.

Because the survey data is based on people’s self-reports of post-COVID symptoms and isn’t compared to a control group of uninfected people, Razak and other doctors said the results should be interpreted with some caution.

The StatsCan report does not indicate how severe people’s post-COVID symptoms were, nor does it indicate whether the symptoms subsided at any point after the three-month mark.

StatsCan’s survey found that a significantly lower proportion of those infected since the Omicron wave are reporting long-term symptoms compared to those infected in the first year and a half of the pandemic.

The survey found that 25.8 percent of Canadian adults who contracted COVID-19 before December 2021 had symptoms at least three months after being infected.

Among those whose cases began as of December 2021, 10.5 percent reported symptoms three months or more after infection.

The lower rate of long-lived COVID among Canadians infected since last December is good news, says Dr. Zain Chagla, an infectious disease specialist in Hamilton who was not involved with the study.

“The people who are really, really suffering the most are people who got infected very early in the pandemic,” Chagla said in an interview with CBC News.

Vaccines Likely Key to Lower Frequency: Physicians

Both Chagla and Razak said the vaccine’s benefit is likely a key reason for the lower incidence of long-COVID among those infected over the past year.

The survey also provides more evidence linking the likelihood of a long COVID to the severity of the disease at first infection.

Symptoms at least three months after infection have been reported by:

• 36.4 percent of Canadian adults who rated their first case of COVID-19 as serious;

• 15 percent of those who rated their baseline case as moderate;

• 6.3 percent of those who classified their first case as mild.

dr Angela Cheung, chief scientific officer at Toronto’s University Health Network, said these figures from Statistics Canada’s report are consistent with previous research.

“I’m glad this survey took place and that we’re actually trying to get a handle on the number of people affected by COVID-19 with ongoing symptoms,” she said in an interview.

The findings may help prepare for demand, researchers say

Cheung, who was not involved in either report, also said the CMAJ study released Monday is important in quantifying the increased use of the healthcare system after COVID-19 infection.

The study, led by researchers from Toronto’s Sunnybrook Research Institute and nonprofit research agency ICES, examined the healthcare utilization of more than 530,000 Ontario residents who were PCR tested for COVID-19 prior to March 31, 2021.

The researchers matched the demographics of those who tested positive and those who tested negative and found “significantly higher rates of health care utilization” at least eight weeks after a positive test.

The researchers found a 47 percent increase in the average number of days spent in hospital per year in women who tested positive, and an average 53 percent increase in men.

The researchers said the findings could help the system prepare for long-COVID-related healthcare demand.