A team of US researchers have identified 12 key symptoms of Long Covid condition -- which persist more than 30 days after a Covid-19 infection.

With over 650 million people globally having been infected with SARS-CoV-2, long Covid represents a significant public health concern that affects quality of life, earnings, and health care costs.

To better understand the prevalence and severity of symptoms, the US National Institutes of Health (NIH) launched Researching Covid to Enhance Recovery (RECOVER-Adult).

Published online in the Journal of the American Medical Association, the study examined 37 symptoms across multiple body areas and organs.

Researchers identified 12 symptoms that most set apart those with and without long Covid: post exertional malaise (worsening of symptoms following even minor physical or mental exertion), fatigue, brain fog, dizziness, gastrointestinal symptoms, heart palpitations, issues with sexual desire or capacity, loss of smell or taste, thirst, chronic cough, chest pain, and abnormal movements.

The findings include a new scoring system for long Covid to help clinicians and researchers better define it and investigate treatments for patients.

"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," said corresponding author Andrea Foulkes, Principal Investigator of the RECOVER, and Professor at Harvard Medical School.

"One of the big takeaways from this study is the heterogeneity of long Covid: long Covid is not just one syndrome; it's a syndrome of syndromes. Understanding this idea is a really important step for doing more research and ultimately administering informed interventions," she added.

The study began enrolling participants in October 2021. Researchers analysed the results of a symptoms survey distributed at 85 hospitals, health centres, and community organisations in 33 states, Washington, D.C., and Puerto Rico.

Over 9,500 individuals completed the survey, including uninfected adults as well as individuals who were six months past infection with Covid-19. The survey, developed in collaboration with clinicians and patient advocates, included 37 different symptoms and corresponding measures of severity.

The results also suggest that re-infections, infection with a pre-Omicron SARS-CoV-2 variant, and absence of vaccination is associated with a higher frequency and severity of long Covid, but the authors emphasise that ongoing research is necessary. (IANS/NS)