After about two years of research, scientists funded by the National Institutes of Health (NIH) have proposed a list of 12 symptoms that can identify long Covid in a step toward finding treatments for the debilitating condition.
This comes as part of the NIH’s $1.2 billion RECOVER research initiative, which seeks to understand, prevent and treat long Covid—the term for lingering or new symptoms following a Covid-19 infection. The paper was published Thursday in the Journal of the American Medical Association.
“Now that we’re able to identify people with long Covid, we can begin doing more in-depth studies to understand the biological mechanisms at play,” co-author Andrea Foulkes, director of biostatistics at Massachusetts General Hospital, says in a statement.
About one in ten of the study’s participants infected with the omicron variant suffer from long Covid, but the condition remains difficult to research. Long Covid affects every person differently, and many of its 200 or more symptoms, which vary in severity and duration, are connected with several other diseases, too. Doctors have no test to determine if a patient has long Covid—the syndrome has no objective characteristic to measure it. Further, what causes some people to develop the condition remains a mystery.
“If you look up simple questions like, ‘how many people get long Covid,’ the answers are all over the place, because people define it differently,” Leora Horwitz, a physician and co-principal investigator for the RECOVER Clinical Science Core at NYU Langone Health, tells the Washington Post’s Amanda Morris. “To really advance the science, we need a common language.”
To help create this language, researchers examined patient data from 9,764 individuals—8,646 who had been infected with Covid-19 and 1,118 who had not. They found some trends among their participants: Long Covid was more common and severe in unvaccinated people, as well as people who had been reinfected or caught Covid for the first time before the 2021 omicron variant emerged, per the statement.
Finally, the team narrowed down a list of symptoms that tend to set apart those with long Covid: loss of smell or taste, fatigue, brain fog, dizziness, gastrointestinal symptoms, heart palpitations, changes in sexual desire or capacity, thirst, chronic cough, chest pain, abnormal movements and post-exertional malaise, or feeling ill after even minor physical or mental effort.
The researchers assigned a point value to each of these symptoms based on how unique it is to long Covid patients. Loss of taste and smell, for example, which is uncommon in people who haven’t had Covid, was given an eight, while dizziness and fatigue were each assigned one point. Scores of 12 or higher meet the researchers’ definition of long Covid.
But this score is not meant for diagnosing patients, since individuals may have any number of these or other symptoms not included in the list, Horwitz tells Lauran Neergaard of the Associated Press. Rather, it’s meant to be a research tool. Still, some with long Covid feel the tool could leave certain patients out.
“Personally, I think that the list of symptoms is too small, but I understand that you have to start somewhere,” Nitza Rochez, a RECOVER study participant who has had long Covid since March 2020, tells the Post. “At least it’s more than what we’ve had in the last two years.”
Others had harsher criticism for the study. “I think people will be underwhelmed by a ‘landmark’ paper that is describing the presence of symptoms that people have long known are a problem,” Jim Jackson, director of behavioral health at the ICU Recovery Center at Vanderbilt University Medical Center who was not involved in the study, says to NBC News’ Erika Edwards.
Jackson and others tell the publication that some of the listed symptoms—namely “brain fog” and “abnormal movements”—are not well-defined, which means they are not as useful as they could be.
But the researchers hope this working definition of long Covid can inform future research that will help diagnose and treat patients.
“I know that we’re all impatient to get answers. We’re all impatient to have evidence-based therapeutic recommendations,” Daniel Griffin, an infectious disease specialist at Columbia University who was not involved in the study, tells CNN’s Brenda Goodman. “But we understand the challenge here. … This is a new disease. This is a new phenomenon. And before we rush in and waste a lot of resources with bad trials, we need to understand what we’re studying. We need to understand the target group.”