Long COVID may now be less common than previously thought

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Long-term COVID can be a severely debilitating condition for those living with it, but the growing list of symptoms and conflicting estimates of how often it occurs makes it very difficult to gauge exactly how many people contract it.

Post-COVID-19 situationas the World Health Organization (WHO) calls it, is also not inevitable for most people who become infected, and now appears to be significantly less common than previous research has suggested – thanks in part to the vaccination.

Based on data from the early pandemic, WHO estimates put the case at between 10 to 20 percent of COVID-19 patients, while Public Health Canada (PHAC) states that it can happen in between 30 to 40 percent of those who were not hospitalized.

Canada’s chief public health official, Dr. Theresa Tam, went so far as to say last May that the coronavirus could affect the long-term. up to 50 percent for all patients, adding that symptoms can be “very broad and non-specific.”

But with estimates that More than half of Canadians Infected with COVID since December after the emergence of Omicron and its highly contagious sub variants, there is a lack of evidence to suggest that there are millions of long-term COVID carriers currently in Canada.

Recent research indicates that the emerging coronavirus for a long time is occurring at a much lower rate than estimates early in the epidemic, before widespread vaccination. PHAC is now working to better understand the true number of cases – while acknowledging that its data is outdated.

“Covid is a long, real thing,” said Bill Hanage, an epidemiologist at TH Chan School of Public Health at Harvard University in Boston. “There are a lot of people suffering from it.”

“But you don’t serve these people by pretending that 40 percent of the population is in this boat. In my opinion, it’s a bit disrespectful for people who are really sick with the long Covid disease to pretend that is the case.”

Watch | What life is like for Canadians living with COVID for a long time:

What is life like for Canadians who have been infected with COVID-19 for a long time

Andrew Chang spoke to Candice Makhan and Adriana Patino about when they realized they had been infected with COVID-19 for so long, how their symptoms were and how it changed their lives. They were joined by infectious disease specialist Dr. Isaac Bogosh to discuss whether vaccines reduce the risk of contracting the COVID-19 virus for a long time.

Estimates are based on old research

Many of the estimates cited by health organizations are based on early data that largely looked at patients in 2020, well before the COVID-19 and Omicron vaccines. Dramatically changed the immune landscape in Canada And around the world.

One study was published in scalpel In July 2021, PHCC cited it as one of its main sources for its estimate that 30 to 40 percent of out-of-hospital patients develop long-term COVID-19, looking at fewer than 1,000 patients between April 2020 and December 2020.

“I assume that because of vaccination and the Omicron variant, fewer people will now be affected by the prolonged COVID virus,” said Clara Lehmann, the study’s lead author and professor in the Department of Internal Medicine at the University of Cologne in Germany. Recent email.

PHAC also cites two systematic reviews as evidence for its high estimates of COVID – a Pre-print study Written by its researchers from late 2021 and not yet peer-reviewed, and a study in Journal of Infectious Diseases from April.

Many of the papers analyzed in the studies dated back to before the advent of the Omicron and COVID-19 vaccines, while a significant proportion also did not have control groups of the general population for comparison. The lead author of the Lancet PHAC study she also cited said she expects the rate to be much lower.

“I think the ratio [of long COVID] said Bhramar Mukherjee, lead author of the Lancet study and professor of biostatistics and epidemiology at the University of Michigan.

“There are many studies now on the vaccinated population, and at first it wasn’t clear what the prevalence was, but there seems to be a significant effect.”

Watch | Some of the long-running carriers of the COVID virus see improvement after vaccination:

Some COVID-19 long-haul carriers see improvement after vaccines

Some long-term carriers of COVID-19 have reported an unexpected improvement in their symptoms after receiving the first dose of the vaccine.

A British study was published this week in temper nature It identified up to 62 symptoms associated with prolonged COVID-19, including hair loss and erectile dysfunction, and found that 5.4 percent of out-of-hospital patients reported at least one symptom three months after infection.

By comparison, 4.4% of people with no recorded evidence of COVID-19 reported at least one symptom — just a 1 percent difference. People in this group were not specifically tested for the study and found negative.

This is in line with the file recent study from the UK Office for National Statistics who found the long-term COVID rate was just over four per cent with penetrating Omicron BA.1 or BA.2 infection in triple-vaccinated adults, which was less than delta 5 per cent.

It’s not entirely clear yet how much vaccination helps prevent COVID for the long haul, said Akiko Iwasaki, professor of immunobiology at Yale University School of Medicine in New Haven, Connecticut. Some studies have shown that this can be done Reduce risk by half Others showed Significantly less benefitbut emerging research suggests that it lowers the rate significantly.

“It’s probably related to the fact that we have some immunity to vaccination and possibly previous infections,” she said. “There may also be some substantial difference between the variables of concern.”

In a statement to CBC News, a PHAC spokesperson explained that “there is currently insufficient pan-Canada data to estimate the number of long-term COVID patients in Canada” and that rates of 30-40 percent on their website “predate Omicron’s arrival.”

“Estimates should not be used to extrapolate how many Canadians they may have.” [long COVID] in 2022 since the arrival of the Omicron variant and its sub-variables,” the statement said, adding that they are currently working on an update systematic review.

“Evidence reviewed by the Primary Health Care Center (PHAC), based on a small number of studies, indicates that vaccination against COVID-19 prior to infection with COVID-19 may help reduce the risk of infection. [long COVID]. “

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 dramatically changed the immune landscape in Canada and around the world. (Peter Hamlin/The Associated Press)

Confusion due to prolonged Covid symptoms

The confusion lies in the different definitions of what COVID actually is, along with the fact that the population’s level of immunity from previous infection and vaccination has significantly altered the risk of contracting it.

And while some symptoms can be life-altering, others may be less severe or difficult to attribute to COVID-19 entirely — making it extremely difficult to study accurately.

“It’s ambiguous,” said Harvard’s Hanage. “The criteria are not consistent enough to allow for strong statements as some people make.” “You have to decide exactly what you mean by long COVID and be aware that there are a lot of different types of long COVID.”

WHO lists Dozens of prolonged COVID symptoms that are not explained by another diagnosis — from fatigue, shortness of breath and cognitive dysfunction to anxiety, depression, sleep disturbances, and loss of taste and smell — can persist for at least two months after injury.

The US Centers for Disease Control and Prevention ranks COVID at least long 19 symptoms Which range widely from general fatigue to respiratory and heart disease, neurological symptoms and digestive problems that can occur after a month or even three months.

PHAC states that there can be Over 100 Long-Term COVID Symptoms Weeks or months after the injury but the list of common ones has been narrowed down to nine – including general pain, discomfort, difficulty thinking or concentrating, and post-traumatic stress disorder (PTSD).

Watch | Doctors search for answers to the long-running coronavirus as patients struggle to recover:

Doctors search for a long-term solution to Covid as patients struggle to recover

Nearly two years after the outbreak of the COVID-19 pandemic, doctors and health experts are searching to find a cause and treatment for the prolonged Covid-19 virus, while patients are simply striving for their own recovery.

“How frequently it occurs depends somewhat on the long definition of COVID, and there is no universal definition currently,” Iwasaki said. “As with everything else, the statistics change at different stages of an epidemic.”

She said the fact that there are more than 200 prolonged COVID symptoms across different health organizations that range in severity and duration in different populations throughout the pandemic adds to the confusion.

“Estimates are all over the place,” said Dr. Angela Cheung, chief scientist and physician at the University Health Network in Toronto who has been researching the long-running COVID-19 pandemic.

“Some will count any one symptom, like if you have one remaining symptom you have had COVID for a long time, and those symptoms may be very mild and not really affect your daily life. While some people have multiple symptoms and are completely exhausted and can’t work.”

The confusion lies in the different definitions of what COVID actually is, along with the fact that the population’s level of immunity from previous infection and vaccination has significantly altered the risk of contracting it. (Peter Hamlin/The Associated Press)

Canada updates its estimates on the emerging corona virus

Canada may soon be able to better handle the true rate of the prolonged COVID virus occurring in the population with the release of a exploratory study From PHAC and Statistics Canada to determine the condition’s prevalence, risk factors, symptoms, and effects on the condition’s daily life.

The first phase of the survey was launched in April 2022, and results are expected early next year. PHAC said in a statement that it also plans to conduct follow-up studies to examine long-term changes in COVID over time and long-term outcomes in those affected.

“We need a better understanding of degree as well,” said Cheung, who works with PHAC and Statistics Canada on the survey.

“Because while people may be more willing to put up with one or two offerings, it doesn’t really affect their activities in daily life or work, while people are less receptive to something that really upsets their lives.”

Iwasaki said that while the long-term rate of COVID may change over time, the condition severely affects a significant proportion of the population who need ongoing support.

“People who had Covid for a long time in the original wave are still suffering,” she said. “Some of them have not recovered.”

Hanage said the situation for the long-running novel coronavirus could be improved by ensuring people have prior vaccination protection, better research into the condition and finding treatments to help those who need it most.

“Even if the actual risk of prolonged, severe COVID symptoms is very low, and I think it really is, that is not comforting for the millions of people who will end up with severe prolonged COVID,” he said.

“It’s just that you are infected individually is more likely than not fully cured.”

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