By A. Pawlowski

As more people recover from COVID-19, some will find their ordeal may not end when the infection is over.

With the disease emerging in China a few months ago, doctors are just starting to get a better understanding of how the new coronavirus impacts long-term health.

For now, it appears most patients who have had mild symptoms can expect no lasting harm, experts said.

“For the vast majority of people who get the coronavirus, they’re not going to have any long-term consequences for it,” Dr. Amesh Adalja, a senior scholar at the Johns Hopkins University Center for Health Security in Baltimore and a spokesman for the Infectious Diseases Society of America.

“It’s going to be like a cold or a flu and they go about their lives once they recover in a week or two from it.”

But survivors of the severe type of the illness may face a much more complicated picture, and not just when it comes to their lungs.

COVID-19 seems to be more than a respiratory disorder, with people also experiencing a gastrointestinal version of the disease.

Doctors are also trying to figure out any long-term impact on the heart and other organs, said Dr. Andrew Freeman, a cardiologist at National Jewish Health in Denver, Colorado, and a member of the American College of Cardiology’s COVID-19 Response Work Group.

“We’re going to see enormous populations of people who have convalesced — who have survived the virus. Then the question is: Do we need to give them echocardiograms? Do we need to do other things to surveil for whatever the long-term (consequences) are?” Freeman said.

"I don’t think we know the answers to those questions yet."

Here’s what doctors have seen so far:

Lungs

COVID-19 patients who developed acute respiratory distress syndrome — a life-threatening lung injury due to infection — and had to be hospitalized in the intensive care unit are more likely to have long-term consequences, Adalja said.

“There are people who are going to have scarring in their lungs from what’s happened and that may not be completely reversible,” he noted. “It’s not just with coronavirus; we see this with all types of pneumonia that lead to ARDS.”

These patients may have diminished lung function that’s going to persist, including decreased exercise capacity that leaves them short of breath.

Some COVID-19 survivors had a 20-30% drop in lung function after recovery and “gasp if they walk a bit more quickly,” doctors in Hong Kong said last month.

In such cases, cardiopulmonary rehab may help in rebuilding strength and capacity, though a person may not return completely all the way back to baseline, Adalja said.

Heart

About 20% of patients with COVID-19 in China had heart damage during hospitalization, a recent study found.

Another study discovered about 16% patients developed arrhythmia, while other reports indicated cases of acute onset heart failure, heart attack and cardiac arrest after coronavirus infection, the American College of Cardiology warned.

People with the severe form of the illness can also develop myocarditis, an inflammation of the heart muscle, and sometimes don’t fully recover by the time they’re discharged from the hospital, Freeman noted. It’s possible this condition could persist in some way.

Whenever there’s enormous demand placed on the heart — in cases when someone is severely sick and on life support, for example, or dealing with an intense inflammatory response — there can always be some element of cardiac injury, he explained.

Plus, any long-term lung disease can have effects on the heart, particularly its right side.

“The lungs and heart are coupled tightly,” Freeman explained. “Sometimes when the lungs are ill, the pulmonary arteries — which are what leaves the right side of the heart — can also develop inflammation, disease or a thickening.”

In addition, viral illnesses can destabilize plaque in the arteries, potentially resulting in a blockage and putting patients at risk of a heart attack.

Kidneys

There’s no evidence COVID-19 hurts the kidneys of people who have mild to moderate infection, but kidney abnormalities have been seen in 25-50% of patients who develop the severe type of the disease, according to the International Society of Nephrology.

Those patients have more protein and red blood cells in their urine. About 15% of them also develop a decline in filtration function.

The new coronavirus “is an infectious organism and can lead to a cascade of immune changes that lead to sepsis, and sepsis is characterized by multiple organ systems being compromised,” Adalja said. “Some individuals with sepsis can get acute kidney injury.”

The long-term health effect of this on COVID-19 survivors is not known, the organization noted.

Brain and mental health

The longer patients have to remain in the ICU, the more likely they are to suffer long-term cognitive and emotional effects of being sedated. Doctors call it "post-intensive care syndrome" or post-ICU delirium, and describe it as a type of post-traumatic stress.

"Often when patients come out of the ICU, they really struggle to think as clearly as they did before," Dr. Amy Bellinghausen, a pulmonary, critical care and sleep medicine fellow at the University of California, San Diego, told NBC News.

She estimated up to two-thirds of ventilated patients may be affected. Possible causes include not getting enough oxygen or blood to the brain, or the medications used to sedate a patient.

Nervous system

Neurologic symptoms may be possible, too. Other coronaviruses that affect humans can invade the central nervous system, so it makes sense COVID-19 may have neurologic manifestations, Dr. Kenneth Tyler, chair of neurology at University of Colorado School of Medicine in Aurora, said.

Indeed, a study published Friday found neurologic symptoms were seen in 36% of 214 COVID-19 patients in China, including dizziness, headache and taste and smell impairment. It's not clear how long they last.

Bottom line: Doctors are still trying to understand any effects that are unique to the new coronavirus.

“There may be some differences in the way the immune system reacts to this (virus),” Adalja said. “We’ll only learn that from long-term studies of survivors.”