- Federally funded scientists have proposed a definition for long Covid based on symptoms identified in a large study published in the Journal of the American Medical Association.
- The definition is based on 12 symptoms that most distinguish people with long Covid from people who didn’t have the coronavirus.
- There is still no systematic, universally accepted definition of long Covid for research, and that could serve as the basis for future tools to diagnose the condition.
- The research is part of the NIH’s massive $1.15 billion RECOVER research initiative that aims to define long Covid, understand what causes the condition and develop treatments.
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Federally funded scientists have proposed a definition of long Covid based on symptoms identified in a large study published Thursday in the Journal of the American Medical Association.
The definition is based on 12 symptoms that distinguish most people with long Covid six months or more after their infection from people who didn’t have the coronavirus.
Since the very beginning of the pandemic, many people have suffered from myriad, sometimes debilitating symptoms that persisted long after they were infected with Covid-19.
Patients long took the name Covid. Scientists call the condition post-acute sequelae, or PASC.
But there is still no systematic, universally accepted definition of long Covid for research, and that could serve as the basis for future tools to diagnose the condition.
“It’s really an effort to come up with a concrete, replicable specific definition for long Covid,” said Dr. Leora Horwitz, study author and professor at NYU Grossman School of Medicine.
The National Institutes of Health-funded study surveyed nearly 10,000 participants at 85 hospitals, health centers and community centers in 33 states.
More than 8,600 patients who had covid were compared to more than 1,100 who did not have the virus.
The research is part of the NIH’s massive $1.15 billion RECOVER research initiative that aims to define long Covid, understand what causes the condition and develop treatments for it. RECOVER is an acronym for Researching COVID to Enhance Recovery.
The symptoms most notable in participants with long Covid included loss of smell and taste, post-exertional malaise, chronic cough, brain fog, thirst, palpitations, chest pain, fatigue, changes in sexual desire, dizziness, gastro- intestinal problems, abnormal movements and hair loss.
The scientists awarded points based on how much each symptom distinguished participants with long Covid from those who did not contract the virus.
A competitor who has 12 points or more is considered to have a long Covid.
For example, loss of smell and taste and post-exertional malaise stood out more than other symptoms, scoring 8 and 7 points, respectively. Palpitations and dizziness, which are characteristic of long Covid, but which are also common symptoms in many other conditions, scored 2 points and 1 point respectively.
Horwitz, author of the study, said the proposed definition of long Covid could help develop a method for doctors to diagnose patients.
But Horwitz said the definition presented in the study is an early working definition, has yet to be refined and is not yet ready for clinical use.
In the absence of a universally accepted definition, many long-term Covid patients have struggled to get proper healthcare, especially early in the pandemic, as some symptoms are common to other conditions, which can make diagnosis difficult.
There are no tests that can diagnose lung covid based on markers in the blood. Scientists participating in RECOVER are trying to understand the underlying biology that causes long Covid, which could potentially lead to such tests in the future.
Horwitz said the proposed definition could help create a rubric to diagnose patients with long Covid in a way similar to Lupus. There is no single blood test that can diagnose Lupus, so doctors also rely on a collection of common symptoms to determine if a patient has the disease.
Horwitz said the goal is to give researchers a more systematic definition that can be used to answer questions about risk factors and how likely Covid is after repeated infection and between different variants of the virus, among other things.
Biological samples from the patients who developed long-term covid during the study could be used to investigate the cause of the condition and potentially help find treatments and guide participation in future clinical trials, according to the study.
The study also found that long Covid was more common in people infected before the omicron variant swept the US in December 2021.
About 17% of patients who enrolled more than 30 days after their infection during omicron developed long Covid. In contrast, about 35% of those infected before the Omicron era developed long Covid.
But patients who were reinfected during omicron were more likely to develop long-term covid than those who reported one infection when the variant surged. About 21% of those with repeated infections who enrolled after 30 days developed long-term Covid, compared to 16% who contracted Covid once.
People who were fully vaccinated were less likely to develop long-term covid, regardless of when they were infected.
About 16% of participants who were aware of their injections who became infected during omicron developed long Covid, compared to 22% who did not receive their injections. Before omicron, 31% of people who were up to date on their vaccinations who got infected developed long-term Covid, compared to 37% who were not vaccinated.