Canada's public health authority (PHAC) website cites the incidence of Long Covid at 30-40%, but current research has it at ~5%. PHAC says its figures are under review and should not be used, but still has the old data on its website.
July 30, 2022 - "Long COVID can be a severely debilitating condition for those who live with it, but the growing list of symptoms and conflicting estimates on how often it occurs make it incredibly difficult to measure exactly how many people it affects. [But] Post-COVID-19 condition, as it's called by the World Health Organization (WHO), ... now appears significantly less common than earlier research suggested — thanks in part to vaccination.
"Based on data from ... early in the pandemic, the WHO estimates placed the condition at a rate of between 10 to 20 per cent of COVID-19 patients, while the Public Health Agency of Canada (PHAC) states it can occur in between 30 to 40 per cent.... Canada's Chief Public Health Officer Dr. Theresa Tam went as far as to say back in May that long COVID can affect up to 50 per cent of all patients, adding that the symptoms can be 'quite broad and non-specific.' But with estimates that more than half of Canadians have been infected with COVID since D ecember after the emergence of Omicron and its highly contagious subvariants, there is a lack of evidence to suggest there are currently millions of COVID long haulers in Canada....
"'Long COVID is real. There are a lot of people suffering from it,' said Bill Hanage,* an epidemiologist at Harvard University's T.H. Chan School of Public Health in Boston. 'But you don't serve those people by pretending that 40 per cent of the population is in that boat'....
"Many of the estimates cited by health organizations are based on early data that largely looked at patients in 2020, long before COVID-19 vaccines and Omicron.... One study published in The Lancet in July 2021, cited by PHAC as one of its main sources for its estimate that 30 to 40 per cent of non-hospitalized patients develop long COVID, looked at fewer than 1,000 patients between April 2020 and December 2020. 'I assume that due to vaccination and the Omicron variant, fewer people will now be affected by long COVID,' Clara Lehmann, a lead author of the study ... said in a recent e-mail. PHAC also cites two systematic reviews as evidence for its high estimates of long COVID.... Many of the papers analyzed in the [review] studies are from before the emergence of Omicron and COVID-19 vaccines, while a significant proportion also had no control groups from the general population to compare against....
"A U.K. study published this week in Nature identified up to 62 symptoms associated with long COVID, including hair loss and erectile dysfunction, and found 5.4 per cent of non-hospitalized patients reported at least one symptom three months after an infection. In comparison, 4.4 per cent of people with no recorded evidence of COVID-19 infection reported at least one symptom.... That's in line with a recent survey from the U.K.'s Office for National Statistics that found the rate of long COVID was just over four per cent with Omicron BA.1 or BA.2 breakthrough infections in triple vaccinated adults....
"In a statement to CBC News, a spokesperson for PHAC clarified that 'there is currently insufficient pan-Canadian data to estimate the number of long COVID patients in Canada' and the rates of 30 to 40 per cent on their website 'predate the arrival of Omicron.... The estimates should not be used to extrapolate how many Canadians may have [long COVID] in 2022 since the arrival of the Omicron variant and sub-variants,' the statement read....
"[Some] confusion lies with the different definitions of what long COVID actually is [as well as] with the fact that the level of immunity in the population from prior infection and vaccination has vastly changed the risk.... And while some symptoms can be life-altering, others can be much less severe or hard to attribute to COVID-19 altogether — making [Long Covid] incredibly difficult to study accurately. 'It's fuzzy, the criteria are not sufficiently settled to permit statements that are as strong as some people make,' said Hanage from Harvard. 'You need to decide exactly what you mean by long COVID and recognize that there are a lot of different sorts of long COVID.'"
Read more: https://www.cbc.ca/news/health/long-covid-estimate-vaccination-omicron-canada-1.6536194
* signatory of the John Snow Memorandum
No comments:
Post a Comment