Long-term COVID may now be less common than previously thought

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Long-term COVID can be a deeply debilitating condition for those living with it, but the list of symptoms and conflicting estimates of how common it is makes it very difficult to accurately gauge how many people it affects.

Situation after COVID-19According to the World Health Organization (WHO), infection is not inevitable for the majority of people who are infected, and it now appears to be much less likely than in previous studies – thanks in part to that. vaccination.

Based on the data at the beginning of the pandemic, the WHO predicts the situation: 10-20 percent The Public Health Agency of Canada (PHAC) said it may be between patients with COVID-19. 30-40 percent not hospitalized.

Canada’s chief public health officer, Dr. Teresa Tam went so far as to suggest in May that there could be a lingering COVID impact Up to 50 percent adding that the symptoms of all patients can be “quite broad and non-specific.”

But with these assumptions more than half of Canadians There is insufficient evidence that there are currently millions of long-term carriers of COVID in Canada, since Omicron and its highly infectious subvariants have been infected with COVID since December.

New research shows that long-lasting COVID occurs at a much lower rate than when the pandemic started, before widespread vaccination. PHAC is now working to better understand the true number of cases – admitting that their data is out of date.

“Long-term COVID is real. There are a lot of people affected by it,” said Bill Hanage, an epidemiologist at Harvard University’s TH Chan School of Public Health in Boston.

“But you don’t serve those people by saying that 40 percent of the population is in that boat. I think it’s a little disrespectful to say that to people who are actually sick with COVID.”

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What life will be like for Canadians with prolonged COVID-19

Andrew Chang talks to Candice Mahan and Adriana Patino about what their symptoms were like when they found out they had long-term COVID-19 and how it changed their lives. Dr. infectious diseases specialist to them. Isaac Bogoch to discuss whether vaccines reduce the risk of long-term COVID-19.

Evaluation based on outdated research

Most of the estimates cited by health organizations are based on early patient data in 2020, long before the COVID-19 vaccines and Omicron. has dramatically changed the immunity landscape in Canada and worldwide.

One study was published The Lancet In July 2021, PHAC reviewed less than 1,000 patients from April 2020 to December 2020.

Clara Lehmann, lead author of the study and professor of internal medicine at the University of Cologne in Germany, said: “I think that because of the vaccine and the Omicron option, fewer people will suffer from prolonged COVID-19.” last email.

PHAC also cites two systematic reviews as evidence of its high assessment of long-term COVID-a preliminary study Written by its researchers at the end of 2021, it has not yet been peer-reviewed and research Journal of Infectious Diseases from April.

Most of the documents analyzed in the study were from the period before Omicron and the COVID-19 vaccine, and a significant number did not contain any vaccines. control groups from the general population for comparison. PHAC, lead author of The Lancet study, also expected the figure to be much lower.

“I believe in proportion [of long COVID] has declined,” said Bhramar Mukherjee, a Lancet study professor and professor of biostatistics and epidemiology at the University of Michigan.

“Now there are a lot more studies with the vaccinated population, and at first it wasn’t clear what the prevalence was, but there seems to be a significant effect.”

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Some long-term carriers of COVID-19 see improvements after vaccines

Some long-term carriers of COVID-19 report a sudden improvement in symptoms after receiving the first dose of the vaccine.

A UK study was published this week nature The study identified up to 62 long-term COVID-related symptoms, including hair loss and erectile dysfunction, and 5.4 percent of hospitalized patients reported at least one symptom three months after infection.

By comparison, 4.4 percent of people with no evidence of COVID-19 infection reported at least one symptom — a difference of only one percentage point. People in this group were not specifically screened for the study and tested negative.

This corresponds to a recent survey According to the U.K.’s Office for National Statistics, the rate of prolonged COVID-19 in triple-vaccinated adults with Omicron BA.1 or BA.2 infection was just over four percent, five percent lower than Delta.

Akiko Iwasaki, a professor of immunobiology at the Yale School of Medicine in New Haven, said it’s not yet clear how much vaccination can help prevent long-term COVID. Some studies have shown that this is possible halves the risk and others showed significantly less profitbut the developing researches lower their rate considerably.

“This may be due to the fact that we have some degree of immunity from vaccination and prior infections,” he said. “There may also be some intrinsic differences between anxiety variants.”

In a statement to CBC News, a PHAC spokesperson explained that “There is currently insufficient pan-Canadian data to estimate the number of long-term COVID patients in Canada” and that the 30-40 percent figures on their website are “before the arrival of Omicron.” .”

“Estimates should not be used to extrapolate how many Canadians there may be [long COVID] Since the arrival of the Omicron variant and sub-variants in 2022,” the statement said, they are currently being updated. systematic review.

“Evidence reviewed by PHAC, based on a small number of studies, suggests that vaccination prior to infection with COVID-19 may help reduce the risk of developing COVID-19. [long COVID].”

Most of the estimates cited by health organizations are based on early data examining patients in 2020, long before the COVID-19 vaccines and Omicron dramatically changed the immunity landscape in Canada and around the world. (Peter Hamlin/Associated Press)

Confusion over chronic COVID symptoms

The confusion lies in different definitions of how long COVID actually lasts, as well as the degree to which a population’s immunity from previous infection and vaccination dramatically alters the risk of developing it.

While some symptoms may be life-altering, others may be less severe or difficult to associate with COVID-19, making an accurate diagnosis incredibly difficult.

“It’s vague, the criteria aren’t settled enough to allow for strong statements like some people say,” said Harvard’s Hanage. “You have to be clear about what you mean by prolonged COVID and recognize that there are different types of prolonged COVID.”

WHO lists Dozens of long-lasting COVID symptoms unexplained by another diagnosis – fatigue, respiratory and cognitive dysfunction, anxiety, depression, sleep disturbances and loss of taste or smell – can last at least two months after infection.

The US Centers for Disease Control and Prevention classifies long-term COVID as a minimum 19 signs ranging from general fatigue to respiratory and heart problems, neurological symptoms and digestive problems that may develop after a month or three.

PHAC can be states More than 100 symptoms of long-term COVID weeks or months after infection, but narrowed the list of common ailments down to nine, including general pain and discomfort, difficulty thinking or concentrating, and post-traumatic stress disorder (PTSD).

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Doctors have been searching for a long-term solution to COVID as patients struggle to recover

Nearly two years after the COVID-19 pandemic, doctors and health professionals are still searching for a cause and a cure for the lingering COVID-19, while patients struggle to simply recover.

“How often this happens depends on the definition of long-term COVID, and there is currently no universal definition,” Iwasaki said. “As with everything, the statistics are changing at different stages of the pandemic.”

According to him, there are currently more than 200 long-term symptoms of COVID in various health organizations, which vary in severity and duration in different populations during the pandemic.

“Calculations are everywhere,” said Dr. Angela Cheung, a senior clinical scientist at the University of Toronto Health, has studied COVID for a long time.

“Some people consider a symptom, like if you have one symptom that lasts, you’ve had COVID for a long time, and that symptom might be very mild and not really affect your daily life.”

The confusion lies in different definitions of how long COVID actually lasts, as well as the degree to which a population’s immunity from previous infection and vaccination dramatically alters the risk of developing it. (Peter Hamlin/Associated Press)

Canada updates long-term COVID estimates

Canada recently a a survey PHAC and Statistics Canada to determine disease prevalence, risk factors, symptoms and impact on daily life.

The first phase of the survey began in April 2022, with results expected early next year. In a statement, PHAC said it also plans to conduct follow-up studies to examine changes in long-term COVID over time and long-term outcomes in victims.

“We also need a better understanding of rank,” said Cheung, who is working with PHAC and Statistics Canada on the survey.

“That’s because people can tolerate one or two symptoms that don’t affect their daily life or work activities, but people are less likely to accept something that’s really disrupting their lives.”

Iwasaki says that while the rate of long-term COVID-19 may vary over time, the condition will severely affect a significant portion of the population in need of ongoing support.

“People who got COVID for a long time in the initial wave are still suffering,” he said. “Some of them have not recovered,” he said.

According to Hanaj, the situation for prolonged COVID can be improved by ensuring people are protected early with vaccinations, improving research on the condition and finding therapies to help those who need it most.

“Even if the actual risk of serious long-term symptoms of COVID is very low, and I actually think it is, that’s not much comfort to the millions of people who are suffering from long-term COVID,” he said.

“It’s not possible to fully recover just because you’re infected individually.”

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