Three years after the onset of the Covid-19 pandemic, people are still suffering from some of the numerous and debilitating effects of their bout with the infection. Up to now, it has not been clear whether these effects were real or imagined, or whether they could be detected biologically. It has lead to much frustration for those afflicted and for the medical profession that is trying to cope with the unknown condition.
Now there is a new blood test could help put some of these doubts to rest and provide a measure of clarity for all those affected.
Scientists have found clear differences in the blood of people with long Covid — a key first step in the development of a test to diagnose the illness.
The findings, published Monday in the journal Nature, offer clues into what could be causing the elusive condition that has perplexed doctors worldwide and left millions with ongoing fatigue, trouble with memory and other incapacitating symptoms.
In the study, Dr. David Putrino and his colleagues compared blood samples of 268 people. Some had Covid but had fully recovered, some had never been infected, and the rest had ongoing symptoms of long Covid at least four months after their infection.
Several differences in the blood of people with long Covid stood out from the other groups.
The activity of immune system cells called T cells and B cells — which help fight off germs — was “irregular” in long Covid patients, Putrino said. One of the strongest findings was that long Covid patients tended to have significantly lower levels of a hormone called cortisol.
A major function of the hormone is to make people feel alert and awake. Low cortisol could help explain why many people with long Covid experience profound fatigue.
“It was one of the findings that most definitively separated the folks with long Covid from the people without long Covid,” Putrino said.
The finding likely signals that the brain is having trouble regulating hormones. The research team plans to dig deeper into the role cortisol may play in long Covid in future studies.
However, while a quick fix might suggest itself, Dr. Marc Sala, who was not part of the research, stated that, “There is no evidence that replacing cortisol in someone with long Covid would be a safe or effective thing to do.”
The researcher suggests this is just the beginning of a new understanding that can apply to Covid as well as other viruses, for example the one that causes Epstein-Barr Syndrome. “We were looking for signals, and we found them,” said Akiko Iwasaki, one of the researchers and a professor of immunobiology and molecular, cellular and developmental biology at the Yale School of Medicine. “Now what we need to do is home in on each of these signals and understand better how the disease has been driven by these signals.”
