Two new large-scale reports provide a clearer picture of the long-term effects of COVID-19 infections on Canadians and the healthcare system.
One report, published Monday by Statistics Canadafound that nearly 15 percent of people who contracted COVID-19 say they experienced persistent symptoms such as fatigue, shortness of breath or brain fog for three months or more after their initial infection.
But compared to earlier phases of the pandemic, the report found that a much smaller proportion of those infected since the Omicron variant hit Canada late last year reported such long-lasting symptoms.
StatsCan, which conducted the study in collaboration 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 Canadian Medical Association Journal (CMAJ), found that people who tested positive for COVID-19 in Ontario in the months after their infection cleared used more hospital and other health care resources than those who tested negative.
The reports are the latest in a growing body of research into the scope of long-term COVID, a collective term for a range of health effects after infection.
Fewer people report prolonged COVID since Omicron: survey
The World Health Organization has estimated that what it calls ‘post-COVID-19 condition’ affects 10 to 20 percent of those infected, but those numbers are based on earlier phases of the pandemic. Newer research suggests COVID is now long happens at a much slower pace.
StatsCan says its data suggests that about 1.4 million Canadian adults — or about five percent of the total population — had symptoms three months after a COVID infection. The study 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,” says Dr. Fahad Razak, an internal medicine specialist and epidemiologist at St. Michael’s Hospital in Toronto, and former chief of the Ontario COVID-19 scientific advisory board.
“Clinicians in the Canadian research community have been eagerly awaiting the results of this, and the data tells us we’re just like other countries,” Razak, who was not directly involved in the study, said in an interview with UKTN News.
Because the study data is based on people’s self-reports of post-COVID symptoms and not compared to a control group of uninfected people, Razak and other doctors said the results should be interpreted with caution.
The StatsCan report does not indicate how severe people’s post-COVID symptoms were, nor does it indicate whether symptoms decreased at any time after the three-month period.
The StatsCan survey found that a significantly smaller proportion of people infected since the Omicron wave report long-term symptoms, compared to those infected during 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 their infection.
Of those whose cases date back to December 2021, 10.5 percent reported symptoms three months or more after the infection.
The lower rate of long-term COVID-19 among Canadians infected since December last year is good news, said Dr Zain Chagla, an infectious disease specialist in Hamilton, who was not involved in the study.
“The people who are really, really suffering the most are people who were infected very early in the pandemic,” Chagla said in an interview with UKTN News.
Vaccines may be key to lower frequency: Doctors
Both Chagla and Razak said the benefit of vaccination is likely a major reason for the lower frequency of long-term COVID among those infected in the past year.
The survey also provides further evidence linking the likelihood of long-term COVID-19 with disease severity at first infection.
Symptoms at least three months after infection were reported by:
36.4 percent of Canadian adults who rated their first case of COVID-19 as severe;
15 percent of those who rated their first case as moderate;
6.3 percent of those who rated their first case as mild.
dr. Angela Cheung, senior physician scientist at the University Health Network in Toronto, said those figures from the Statistics Canada report are consistent with previous research.
“I’m pleased that this research has happened and that we are actually trying to get to grips with the number of people affected by COVID-19 with persistent symptoms,” she said in an interview.
Findings could help prepare for question, researchers say
Cheung, who was not involved in either report, also said the CMAJ study published Monday is important for quantifying the increased use of the health care system following a COVID-19 infection.
The study, led by researchers from Toronto’s Sunnybrook Research Institute and nonprofit research firm ICES, looked at the health care use of more than 530,000 Ontario residents who were tested for COVID-19 via PCR before 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 use” in the period starting at least eight weeks after a positive test.
The researchers found a 47 percent increase in the average number of hospital days per year among women who tested positive and an average 53 percent increase in men.
The researchers said the findings could help the system prepare for the healthcare demand associated with long-term COVID.