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Many post-COVID patients get new medical problems, US study finds

Hundreds of thousands of people in the United States have sought medical care for post-COVID health problems that they had not been diagnosed with before becoming infected, according to the largest study to date of long-term symptoms in COVID-19 patients. This includes people whose coronavirus infection was mild or asymptomatic.

According to The New York Times, the study by FAIR Health – an independent national non-profit aimed at helping people to understand healthcare costs and coverage – tracked the health insurance records of nearly two million people who contracted the coronavirus last year.

It found that one month or more after their infection, almost one-quarter, or 23%, sought medical treatment for new conditions. Those affected were all ages, including children.

Their most common problems were pain, including in nerves and muscles; breathing difficulties; high cholesterol; malaise and fatigue; and high blood pressure. Other issues included intestinal symptoms; migraines; skin problems; heart abnormalities; sleep disorders; and mental health conditions like anxiety and depression, wrote Pam Belluck in The New York Times article of 15 June 2021.

Post-COVID health problems were common even among people who had not fallen sick from the virus at all, the study found. While nearly half of patients who were hospitalised for COVID-19 experienced subsequent medical issues, so did 27% of people who had mild or moderate symptoms and 19% who said they were asymptomatic.

“One thing that was surprising was the large percentage of asymptomatic patients in that category of long COVID,” said Robin Gelburd, president of FAIR Health, which conducted the study based on what it says is the nationʼs largest database of private health insurance claims, according to The New York Times.

More than half of the nearly two million patients whose records were evaluated reported no symptoms from their COVID infection. Forty percent had symptoms but didn't require hospitalisation, including 1% whose only symptom was loss of taste or smell; only 5% were hospitalised.

Gelburd said the fact that asymptomatic people can have post-COVID symptoms is important to emphasise, so that patients and doctors know to consider the possibility that some health issues may actually be after-effects of the coronavirus.

“There are some people who may not have even known they had COVID,” she said, “but if they continue to present with some of these conditions that are unusual for their health history, it may be worth some further investigation by the medical professional with whom they're working.”

The report analysed records of people diagnosed with COVID-19 between February and December 2020, tracking them until February 2021. It found that 454,477 of them consulted health providers for symptoms 30 days or more after their infection, The New York Times reports.

“The strength of this study is really its size and its ability to look across the range of disease severity in a diversity of age groups,” said Dr Helen Chu, an associate professor of medicine and infectious diseases at the University of Washington School of Medicine, who was not involved in the report. “This is a hard study to do with that much data.”

The report “drives home the point that long COVID can affect nearly every organ system,” said Dr Ziyad Al-Aly, chief of the research and development service at the VA St Louis Health Care System, who was not involved in the new study. “Some of these manifestations are chronic conditions that will last a lifetime and will forever scar some individuals and families.”

The most common issue for which patients sought medical care was pain, including nerve inflammation and aches and pains associated with nerves and muscles, which was reported by more than 5% of patients or nearly 100,000 people, more than a fifth of those who reported post-COVID problems. Breathing difficulties, including shortness of breath, were experienced by 3.5% of post-COVID patients.

Nearly 3% of patients sought treatment for symptoms that were labelled with diagnostic codes for malaise and fatigue, according to The New York Times.

Other new issues for patients, especially adults in their 40s and 50s, included high cholesterol, diagnosed in 3% of all post-COVID patients, and high blood pressure, diagnosed in 2.4%, the report said.

Relatively few deaths, 594, occurred 30 days or more post-COVID, and most were among people who had been hospitalised for their coronavirus infection, the report found.

The study, like many involving electronic records, only addressed some aspects of the post-COVID landscape. It did not say when patients’ symptoms arose or how long the problems persisted, and it did not evaluate exactly when after infection patients sought help from doctors, only that it was 30 days or more. The New York Times lists other study limitations.

But overall, experts said, the reportʼs findings underscore the widespread and varied nature of post-COVID symptoms.

“People with long COVID need multidisciplinary care,” said Al-Aly, “and our health systems should adapt to this reality and develop capacity to deal with these patients.”

Full story on The New York Times site, see the link below.


Study details

A Detailed Study of Patients with Long-Haul COVID – An analysis of private healthcare claims

Published by FAIR Health on 15 June 2021.



Many patients recover from COVID-19 within a few weeks, but some exhibit persistent or new symptoms more than four weeks after first being diagnosed. Patients with such post-COVID conditions are variously referred to as having long-haul COVID, long COVID or post-acute sequelae of COVID-19 (PASC).

Using longitudinal data from a database of over 34 billion private healthcare claim records, FAIR Health studied a total of 1,959,982 COVID-19 patients for the prevalence of post-COVID conditions 30 days or more after their initial diagnosis with COVID-19.

To FAIR Health’s knowledge, this is the largest population of COVID-19 patients so far studied for post-COVID conditions. The patients’ post-COVID conditions were analysed, with the most common conditions identified. Particular attention was given to age and gender, mental health conditions and death. Among the key findings:


  • Of patients who had COVID-19, 23.2% had at least one post-COVID condition.
  • Post-COVID conditions were found to a greater extent in patients who had more severe cases of COVID-19, but also in a substantial share of patients whose cases lacked symptoms. Of patients who were hospitalised with COVID-19, the percentage that had a post-COVID condition was 50%; of patients who were symptomatic but not hospitalised, 27.5%; and of patients who were asymptomatic, 19%.
  • The five most common post-COVID conditions across all ages, in order from most to least common, were pain, breathing difficulties, hyperlipidemia, malaise and fatigue, and hypertension.
  • The ranking of the most common post-COVID conditions varied by age group. For example, in the pediatric population (0-18), pain and breathing difficulties were the top two conditions, as in the all-ages cohort, but intestinal issues, rather than hyperlipidemia, were the third most common.
  • Most of the post-COVID conditions that were evaluated were associated more with females than males. In the case of 12 conditions, however, males more commonly had the condition diagnosed than females. For example, of patients who had post-COVID cardiac inflammation, 52% were male and 48% female. By age, the largest share (25.4%) with this condition was found in a young cohort – individuals aged 19-29.
  • Of the four mental health conditions evaluated as post-COVID conditions, anxiety was associated with the highest percentage of patients after COVID-19 in all age groups. Depression was second, adjustment disorders third and tic disorders fourth.
  • The odds of death 30 days or more after initial diagnosis with COVID-19 were 46 times higher for patients who were hospitalised with COVID-19 and discharged than patients who had not been hospitalised (odds ratio [OR]=46.020, 95% confidence interval [CI], 34.778-60.897, P<0.001). Of COVID-19 patients who were hospitalised and discharged, 0.5% died 30 days or more after their initial diagnosis.
  • Among COVID-19 patients with pre-existing conditions, intellectual disabilities were associated with the highest odds of death 30 days or more after initial COVID-19 diagnosis (OR=3.082, 95% CI, 1.183-8.029, P=0.0212).


New York Times story – Many post-COVID patients are experiencing new medical problems, study finds (Restricted access)

FAIR HEALTH white paper – A Detailed Study of Patients with Long-Haul COVID – An analysis of private healthcare claims (Open access)




Increased risk of death and serious illness among COVID-19 survivors

One-in-10 have long-term effects 8 months after mild COVID-19 — Swedish study

Long-haul COVID-19 associated with white, female, middle age — UK hospital study

30% of COVID-19 patients have lingering symptoms 6 months later — Washington study



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