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It was a Tuesday in late March when Julia Henry first felt the body aches and dry cough that signaled the start of her bout with COVID-19. By that weekend, her husband and three children also were sick. But the kids were fine less than a week later, her husband within two weeks.

"My husband just woke up one day starting to feel back to normal, and I kept waiting for that day when I would have that feeling. But I never did. I never did," said Henry, a 40-year-old physical therapist from New Hampshire.

"For more than two months, I couldn't do much of anything," she said. "Now after three months, I'm finally starting to be able to do some normal, everyday things, like play with my kids or cook dinner for my family."

As of early July 6, there have been nearly 2.9 million confirmed cases of COVID-19 in the United States, according to . Of those, 906,763 – about 31% – are listed as "recovered." But recovery isn't the same for everyone. The World Health Organization reports the median time for recovery is up to two weeks for those with mild cases, while those with more severe cases can take up to six weeks for symptoms to resolve.

Some people, however, say they continue to experience symptoms months after infection. In doctor visits and on social media groups, a growing number of patients report lingering symptoms ranging from mild issues, such as continued loss of taste or smell, to more serious ones, such as heart palpitations, chest pain, shortness of breath, extreme fatigue, cognitive difficulties or recurring fevers. Whether these symptoms eventually resolve or whether they signal permanent damage from the virus remains unknown.

"It has been just six months since the virus was detected in China, so nobody can tell you for sure if these are short-term or long-term complications," said Dr. Samer Kottiech, a cardiologist in New York City who estimates 90% of his patients who come in after COVID-19 infections experience prolonged symptoms.

Kottiech, who was himself infected in March, said he hasn't fully recovered either.

"The biggest problem is that my lung capacity is still a little bit decreased," he said. "I used to be very active. Now I don't feel like I can exercise like I used to."

With little data to go on, it is too soon to draw conclusions about what's happening to those with lingering issues, said Dr. Avindra Nath, head of clinical neurology at the National Institutes of Health's Institute for Neurological Disorders and Stroke.

He believes several things could be occurring: the patient could have an underlying condition, such as heart disease or diabetes, which they didn't know was there prior to infection; the virus, or the body's immune system response to it, could be causing new damage; or, the patient may be experiencing something called post-viral fatigue syndrome, a condition reported in some patients infected with other coronaviruses, such as SARS and MERS.

"What we know from these other viral infections is that they can cause problems that last for years," Nath said.

Nath is preparing to enroll patients in a study that will investigate what's going on in the immune systems of people who don't fully recover from COVID-19.

"There is some abnormality in the immune system that's doing it," he said. "We want to find out what those abnormalities are. Once you figure that out, you can potentially treat them."

Unlike trying to unravel what's happened to the immune systems of patients who have felt ill for years, Nath said, "we now have an excellent opportunity, because we know what these patients had and exactly when they had it. It is early enough in the course of this illness that we can learn a lot about how and why these symptoms are occurring, which could have broad implications for all people with post-viral syndrome."

However, people with lingering COVID-19 symptoms shouldn't assume they'll stay ill for years, Nath said. "I want to reassure people there is still time for them to get better. Even if they are only gradually improving, if they are getting better at all, they will probably continue to do so."

Editor's note: Because of the rapidly evolving events surrounding the coronavirus, the facts and advice presented in this story may have changed since publication. Visit Heart.org for the latest coverage, and check with the Centers for Disease Control and Prevention and local health officials for the most recent guidance.

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