1 of 2 | A new study found for the first time that patients who suffer from debilitating fatigue and other symptoms of long COVID have medically distinct responses to the SARS-CoV-2 virus. File Photo by geralt/Pixabay
Sept. 25 (UPI) -- Medical distinctions in patients who experience brain fog, extreme fatigue and other symptoms associated with "long COVID" have been found for the first time, researchers said in a study published Monday.
The discovery that patients who complain of debilitating symptoms many months after their exposure to the SARS-CoV-2 virus do, in fact, exhibit different immune and hormonal responses to infection marks the first evidence that "long COVID" is a distinct medical condition, according to a new study by researchers at Yale School of Medicine and Icahn School of Medicine at Mount Sinai.
Their findings, published in the journal Nature, shows "distinct responses" in blood samples submitted by 268 long COVID sufferers compared to others who have had COVID-19 with no long-term symptoms and with those who had no known prior infections.
The knowledge of those distinctions will for the first time help researchers identify the causes -- and potentially explore cures -- for an often debilitating illness that has afflicted millions of people worldwide, the authors said.
"If you are a doctor doing routine lab work on these patients, you are not going to find these signals," said Akiko Iwasaki, Sterling Professor of Immunobiology at Yale and co-senior author of the paper.
An estimated 7.5% of people infected with the SARS-CoV-2 virus in the United States later suffer from long COVID, with patients frequently reporting unremitting fatigue, malaise after exercise and a series of other dysfunctions.
While the biological processes associated with the development and persistence of long COVID remain unclear, the latest discovery could provide a roadmap for tracking down a cause. The researchers found that the activity of certain immune system cells differ in long COVID patients, and that they had "markedly lower" levels of cortisol, a steroid hormone released by the adrenal glands in times of stress.
"Once we have more information on these signals, we can start to think about designing the right trials to treat this condition," Iwasaki said.
But, they cautioned, these discoveries are unlikely to lead to a "silver bullet" in treating long COVID because "it is an illness that infiltrates complex systems such as the immune and hormonal regulation," added co-senior study author David Putrino of the Icahn School of Medicine at Mount Sinai in New York.