Long Covid blood test shows differences in immune system, research finds

More than three years into the pandemic, millions of people suffering from long Covid finally have scientific proof that their condition is real.

Scientists have found clear differences in the blood of people with long-term Covid – an important first step in the development of a test to diagnose the disease.

The findings, published Monday in the journal Nature, also offer clues as to what may be causing the elusive condition that has puzzled doctors around the world and left millions of people with persistent fatigue, memory problems and other debilitating symptoms. Have left with.

This is the first research to prove that “long COVID is indeed a biological disease,” said David Putrino, principal investigator of the new study and professor of rehabilitation and human performance at the Icahn School of Medicine at Mount Sinai. New York.

Dr. Mark Sala, co-director of the Northwestern Medicine Comprehensive COVID-19 Center in Chicago, called the findings “important.” He was not associated with the new research.

“This will need to be investigated with more research, but at least it’s something because, frankly, right now we don’t have any blood tests” to diagnose long-lived COVID, he said. Or to help doctors understand why this is happening.

Putrino and his colleagues compared blood samples from 268 people. Some had COVID but recovered completely, some were never infected, and others continued to have long-term COVID symptoms, at least four months after infection.

Many differences were found in the blood of people suffering from long-term Covid compared to other groups.

Putrino said the activity of immune system cells called T cells and B cells – which help fight germs – was “dysregulated” in long-lived Covid patients. One of the strongest findings, he said, was that long-lived Covid patients had significantly lower levels of a hormone called cortisol.

A major function of hormones is to make people feel alert and awake. Low cortisol may help explain why many people with long-term COVID experience extreme fatigue, he said.

“This was one of the findings that definitely separated people with long-term COVID from people without long-term COVID,” Putrino said.

This finding possibly indicates that the brain is having trouble regulating the hormone. The research team plans to delve deeper into the role of cortisol in long-term COVID in future studies.

In the meantime, doctors do not recommend raising a person’s cortisol levels in an attempt to “fix” the problem.

“There is no evidence that cortisol replacement would be safe or effective in someone with long-term COVID,” Salas said.

The study also found that dormant viruses, such as mononucleosis, Epstein-Barr, resurface in long-term Covid patients. However, it is unclear whether those chronic viruses are causing symptoms or signal a problem within the immune system.

“We were looking for signals, and we found them,” said Akiko Iwasaki, one of the researchers and professor of immunobiology and molecular, cellular and developmental biology at Yale School of Medicine. “Now we need to understand each of these signals and better understand how these signals drive disease.”

Investigators did not find significant evidence that Long Covid is the result of an autoimmune disorder in which the body attacks itself.

Joshua Roman practices the cello at his New York City home on Sunday. Long Covid left Roman with uncontrollable tremors, threatening his career.Courtesy Jonathan Yap

Dr. Clinton Wright, director of the clinical research division of the National Institute of Neurological Disorders and Stroke, said additional studies will be necessary to find other ways Covid can cause long-term symptoms. One theory is that the virus is hiding in brain tissue or other organs.

“We’re really interested in whether the virus is still present in the body,” he said. “It’s really hard to do that by measuring blood.” He was not involved in the new study.

Long COVID affects 1 in 13, or 7.5%, of American adults, according to the Centers for Disease Control and Prevention.

These findings provide hope to patients like Joshua Roman, 39, of New York City, who participated in the study.

“We’re in such a mysterious quagmire of symptoms,” he said. “My long Covid treatment is just managing the symptoms.”

Roman, a professional musician who plays the cello, takes daily medication to reduce long-term body tremors that affect his ability to perform.

He said, “It would be great if we could get to the thing that caused me to move in the first place, but we still don’t know exactly what that is.”

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