About 3.5 million Canadian adults have suffered long-term symptoms following a COVID-19 infection, according to Statistics Canada.

Among those affected, just under 80 per cent have been experiencing symptoms for six months or more.

More than 40 per cent have been suffering for a year or more.

More than half – 58.2 per cent – of those who ever reported long-term symptoms were still experiencing them in June 2023.

The 3.5 million people with long-term symptoms represent roughly one in every nine Canadian adults.

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StatCan – which worked on the study with the Public Health Agency of Canada – said people under 18 were excluded from its survey.

The data were based on self-reported information and did not include blood or saliva tests to check for past or present COVID-19 infections.

According to the report, which was published today, about seven in 10 people who had symptoms in June were experiencing them “every day or almost every day” when they were “at their worst.”

Nearly half (49.7 per cent) with long-term symptoms reported no improvement over time.

Meanwhile most sufferers (66.4 per cent) said they did not receive adequate treatment or support. 

Only about a fifth (21.1 per cent) said they were given adequate care.

The most common symptoms of so-called “long COVID” are shortness of breath, fatigue and cognitive dysfunction, according to the World Health Organization (WHO).

But there have been “over 200 different symptoms” reported in connection with the condition, the global body explained.

These conditions “can have an impact on everyday functioning,” WHO said.

The study found that 64.4 per cent of Canadians had either tested positive for COVID-19 or had a suspected infection.

Nearly 20 per cent of the adult population reported having two or more COVID-19 infections.

“These numbers, however, are likely an underestimate of the true number of infections by June 2023, as individuals may not always be aware that they are or have been infected," StatCan added.

The researchers also said their study appeared to show that people infected with COVID-19 earlier in the pandemic were more likely to develop long COVID.

But that cohort “also had more time since their first infection to fall ill from COVID-19 again,” they explained.

They concluded: “More sophisticated studies and analyses are required to explain the association between reinfection and the likelihood of developing long-term symptoms.”

Read more about long COVID here.

The StatCan study can be accessed here.