Experts say vaccines are likely to reduce the risk of long-term COVID, but how much?

Jennifer Ferreira

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TORONTO (CTV network) — As more details are revealed about the long-term effects of COVID-19, experts say that vaccination provides a prophylactic effect against long-term COVID, also known as acute sequelae SARS-CoV-2 infection (PASC). It says it’s likely. But an important question that hasn’t been answered yet is how much protection it provides.

“All the collective evidence shows the fact that vaccines reduce the risk of developing long-term COVID,” said Dr. Kieran Quinn. CTVNews.ca In a telephone interview on Wednesday. Quinn is a clinician scientist at the University of Toronto and the Sinai Health System, leading a large research program to study long-term COVIDs.

A recently published study in the Journal of Nature Medicine found that COVID-19 vaccination reduced the risk of developing long-term COVID by 15%. Long COVID is when the symptoms of the first COVID-19 infection last for about 12 weeks or more after infection. As part of the study, researchers surveyed approximately 34,000 people who experienced breakthrough infections and compared the data with a control group consisting of millions of people. The data was taken from a medical database belonging to the US Department of Veterans Affairs.

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This number is not as high as some other studies suggest. Early studies originating in the United Kingdom showed that the vaccine reduced the risk of developing long-term COVID in adults by 50%, but it included self-reported data collected from a small number of people. Some may be disappointed with the latest data, according to Quinn, but it’s still a “positive sign” that vaccines play a role in protecting against long-term COVIDs.

“We are discussing over 550 million COVID infections worldwide, and according to the estimates you believe, 20-40% of people have long-term and persistent consequences of acute COVID infections. “I will.” .. “If vaccination reduces the risk of developing these protracted symptoms by 15%, the vaccine will help 30 million people.” Research Limits

One of the limitations of research originating in the United States is the lack of a clear breakdown of the underlying health status of the people involved, said Dr. Dale Carina, an infectious disease specialist at Joseph Brant Hospital in Burlington, Ontario. .. Knowing the different types of illnesses and medical conditions that people have can show how well their immune system responds to vaccination, he said.

Without these details, Kalina said it would be difficult to know exactly how much protection would be available against a long COVID if someone was vaccinated.

“Especially as we get older, if we have certain comorbidities … the immune response to the vaccine is not expected to be very strong, so the vaccine is not expected to work well for acute COVID. [infection]”Carina said CTVNews.ca In a telephone interview on Wednesday. “I think it could extend to long COVID symptoms, but this study doesn’t tell us.”

In addition, the Department of Veterans Affairs’ population is predominantly male, which was reflected in the cohort observed as part of the study. As a result, the data are not always applicable to the general public, said Dr. Brian Conway, an infectious disease expert and medical director at the Vancouver Infectious Diseases Center.

“These are American veterans, mostly comorbidities, and older men who chose to engage in care as a result of illnesses such as COVID,” he said. CTVNews.ca In a telephone interview on Wednesday. “Therefore, we are choosing people who are at high risk of complications.”

It is also important to consider studies that suggest that long COVIDs have a disproportionate effect on women compared to men. A recently published study in the Journal of Women’s Health showed that women with long COVIDs showed more symptoms than men suffering from this condition. With new evidence that women’s gender is a risk factor for developing long-term COVID, further research is needed to determine how vaccination affects this group, Quinn said. I am saying.

Still, Conway said young and healthy people are likely to benefit even more from the vaccine when it comes to long-term protection from COVID. This is because they do not have the same risk factors that can have long-term effects with COVID-19, such as old age and underlying illness.

“For me, the fact that in a population at high risk of long COVID could show the benefits of vaccines of all sizes, it is very much that in a healthier population there are even more benefits to reducing vaccines. Promising. Long COVID risk, “Conway said. “There is no data to prove it yet.”

A US study does not specify the dose of COVID-19 vaccine received by each person involved, but both Quinn and Conway are better protected, for example, those who have been vaccinated three times. It states that it is unlikely to develop long-term COVID. People who have only been vaccinated twice.

Previous studies comparing the efficacy of two and three doses of the COVID-19 vaccine show that three doses provide enhanced protection against symptomatic disease and serious outcomes as a result of Omicron infection. Is shown. Vaccination is less likely to get infected with COVID-19, less likely to be hospitalized or die from the infection, and therefore less likely to develop long-term COVID, Quinn said. I am.

“By reducing the risk of infection and the risk of severe infections that lead to hospitalization or admission to the intensive care unit, we can reduce the risk of long-term COVID overall,” he said. What we know (and don’t know) about LONG COVID

Researchers have still determined the exact cause of long-term COVID, but some of the underlying factors being studied include damage from the original process of infection, an abnormal immune response to the virus, and the body after acute. Contains a pocket of SARS-CoV-2 that may remain in COVID 19 infection.

New evidence indicates that viral particles can persist in the intestine after an acute infection, causing symptoms such as diarrhea, Quinn said. Current vaccines may not adequately address this result and may require a complete alternative treatment to minimize the effects. It is also unclear whether severe cases of COVID-19 inevitably increase the likelihood of developing long-term COVID.

“The mechanism by which long COVIDs occur is not yet fully understood. Treatment cannot always be expected to target any of them until we understand what is the root cause of the problem.” Quinn said. .. “Vaccination targets only some of the factors that cause long COVID.”

Different medical institutions also have different definitions of what is considered a long COVID. The World Health Organization (WHO) defines a long COVID, or condition after COVID-19, as a symptom that lasts at least 3 months after the onset of SARS-CoV-2 infection. If the COVID is long, the symptoms “cannot be explained by alternative diagnosis,” WHO says. The Public Health Agency of Canada has a similar definition for long COVIDs.

Meanwhile, according to the US Centers for Disease Control and Prevention, “at least four weeks after infection begins when the post-COVID condition is first identified.”

“That’s an eight-week difference,” Quinn said. “It’s a very long period and it will have a substantial impact on the total number.”

In addition, there are various symptoms associated with long COVID, Conway said. In fact, as many as 203 symptoms are associated with this condition, according to a study published in The Lancet in 2021. Most of these symptoms fall into three different categories, including decreased respiratory capacity such as fatigue and shortness of breath. And memory issues. According to experts, the fact that these symptoms are fairly generalized makes the detection and treatment of long COVIDs increasingly difficult.

“Symptoms are ambiguous,” Kalina said. “”[They’re] It may reflect the phenomena seen in the world of infectious diseases. In this phenomenon, the condition leads to a post-infection inflammatory condition, which is not very well defined. “

Despite the uncertainties about long COVIDs, such studies help to better delineate what the treatment should look like, Quinn said.

“I hope this all tells you how to treat it. [long-COVID patients]Health policy interventions and how to organize our healthcare system to provide quality care to people with post-COVID conditions, “he said.

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