why the disease carries long-term health risks, even after mild forms

why the disease carries long-term health risks, even after mild forms

“Living with the virus.” When it appeared, this slogan described a distant future. It now summarizes the attitude adopted in most European countries, including France, where health restrictions have almost disappeared. More than 130,000 people test positive for Covid-19 every day, a total never reached before the end of 2021, but the subject has disappeared from public debate. Yet the virus has not ceased to be dangerous. It still kills an average of 101 people a day, most of them vulnerable or unvaccinated. A series of recent studies have also lifted the veil on its long-term effects: after an infection, the risk of other diseases increases, even for those who do not have a risk factor, do not develop a severe form and are not affected by the long Covid.

In April 2021, a first study by three researchers from the University of St. Louis (USA), published by the journal Nature*, identified a myriad of health problems that affected people with Covid-19 more frequently. Thanks to a vast database of U.S. Army veterans’ health, the authors compared nearly 5 million non-patients and 77,000 tested positive on the 30th day after their infection. Five months later, they had more respiratory problems and more “disorders of nervous and neurocognitive system, mental health, metabolism, cardiovascular, gastrointestinal, malaise, fatigue, musculoskeletal pain and anemia” that people with a similar profile have never tested positive. Even outpatients were at risk for sequelae.

Since then, this database has been used in several studies by the same team, including one on cardiovascular risk, published in February in Nature*. “It shows a risk multiplied by 1.5 or 2 on all events”, not just well-known heart inflammation in Covid-19 patients, observes Ariel Cohen, a former president of the French Society of Cardiology. In those tested positive (more than 150,000 were observed), the risk of stroke is 1.52 times higher in the year after infection, the risk of pulmonary embolism is 2.93, and the risk of syndrome coronary acute par 1.72.

“At the beginning of the pandemic, Covid-19 was thought to be simply a source of compensation for existing risks.”, recalls Ariel Cohen. That is, people predisposed to these problems reported them during a Sars-CoV-2 infection. The results of these American researchers are “a surprise”he admits.

“This study shows that there is an aggravated risk associated with the infection itself and that it does not go away over time as we thought.”

Ariel Cohen, former president of the French Society of Cardiology

à franceinfo.fr

If the way the virus causes such sequelae is not entirely clear, patient observation has already shown “the virus is attacking the blood vessel wall”which in particular promotes the appearance of clots, says Olivier Robineau, an infectiologist at the hospital in Tourcoing (North).

Covid-19 patients also have a higher risk of developing kidney disease, according to a study by the same US team, published in November in Covid-19. the Journal of the American Society of Nephrology*. In particular, the data point to a three-fold increased risk of end-stage renal disease in former Covid-19 patients (and 2.15 in those who were not hospitalized). Indeed, because it creates vascular problems, the virus can affect a large number of organs. “All these organs are vascularized. As soon as the function of the artery is impaired, there is a risk that they will be affected.”says cardiologist Ariel Cohen.

In the minds of the general public, Covid-19 is more associated with symptoms such as loss of taste and smell. But they point out that the virus also affects the brain and nervous system. Covid long patients report difficulty concentrating and a form of “mental fog”. A study on the brain of monkeys infected with the virus, published on April 1 in Nature Communications*showed damage “May lead [à ces] Long-term neurological symptoms of long Covid “including in animals that have not developed a severe form.

“Researchers warn of dementia risk” favored by the damage caused by the virus, reports Olivier Robineau. The authors of a published article by the magazine Science* in January, note the damage observed in some patients “raise the possibility that the infection may accelerate or trigger the future development of neurodegenerative diseases such as Alzheimer’s or Parkinson’s disease.”

For now, this hypothesis remains more vague than that of cardiovascular problems, says Olivier Robineau, who recalls that these disorders would take years to appear. However, U.S. veterans’ health data show an increased risk of cognitive decline (1.8-fold) or depression (1.39-fold) in the year after infection, according to a study released Feb. 16 by the British Medical Journal*.

This statistical approach has its limitations. A final study of these data, published on March 21 in The Lancet*, notes that people cured of Covid-19 are more likely (+ 40%) to develop type 2 diabetes in the following year. The pandemic will leave “a legacy of chronic diseases”says its main author, Ziyad Al-Aly, in Nature*. Eric Renard, vice president of the Francophone Diabetes Society, sees no indication that the virus itself causes diabetes.

“The most obvious link is a revelation link. Covid-19 stresses the body, which can reveal latent diabetes.”

Eric Renard, vice president of the Société francophone du diabète

à franceinfo.fr

The possibility that the virus is just a trigger is recognized by American scientists and corresponds to what is observed after other infections. Eric Renard does not believe in the risk of a type 2 diabetes epidemic: “These patients will have just discovered their diabetes in an unusual way, with insulin treatment right away, but they will be back in line.” The study has the potential to draw physicians’ attention to the value of measuring the blood sugar of people with Covid-19, especially if they have other risk factors for diabetes.

“You have to stay calm”, argues the infectiologist Olivier Robineau. Recent studies show “an undisputed over-risk” of certain pathologies for Covid-19 patients, “but on events that remain rare. We’re not going to have an outbreak of pulmonary embolism.” He also points out that other elements, such as tobacco and food, are much heavier risk factors in the development of cardiovascular disease, for example.

“There’s no reason to scare people whose infection has subsided and are doing perfectly well.”adds Jérôme Larché, reference for the monitoring of the long Covid in Occitania. “We just need to encourage them to see if there’s a concern.” Before monitoring all people who are cured of Covid-19, it is important to identify and guide those who are experiencing prolonged symptoms. “big challenge”, he explains. Another priority “is catching up with many patients due to the pandemic”recalls cardiologist Ariel Cohen.

The study of the aftermath of Covid-19 is still in its infancy. Further work will need to confirm this and refine the risk measurement of Covid-19, on populations more representative than U.S. Army veterans, an older and average male audience.

These risks of Covid-19 remain, according to these same studies, proportional to the severity of the disease: a reassuring finding while the rise of the Omicron variant and vaccination have decreased the share of severely affected patients. But for Jérôme Larché, what is known about the aftermath encourages “activate all possible levers to avoid being contaminated, from vaccine to wearing mask”. “Covid-19 is anything but a small, unintended transient infection”he recalls.

* Links with an asterisk lead to publications in English.

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