In another study, CT scans taken over a month of 90 Wuhan coronavirus patients found that of the 70 discharged from the hospital, 66 had mild to substantial residual lung abnormalities on their last CT scans, which showed ground-glass opacity, said a March paper published online in Radiology.

Chronic cardiac complications could arise in patients even after recovery as a result of persistent inflammation, according to an April 3 paper by doctors at the Cedars-Sinai Medical Center in Los Angeles. They based their analysis on patient data from Italy and China.

SARS Evidence
For clues on how Covid-19 may leave its mark, doctors and researchers are looking to the experience of SARS. Some survivors suffered long-term effects years after they first succumbed to the disease, which is part of the same family as the new coronavirus.

Researchers in China analyzed 25 SARS patients 12 years after they contracted the virus, contrasting their results with a control group who were not infected with SARS. The study found that more than half of the recovered patients suffered another lung infection since their bout with SARS and also had higher cholesterol levels. Additionally, half the patients had at least five colds in the previous year — a characteristic no one in the control group shared, said the 2017 paper published online in Scientific Reports.

“These data demonstrated that the recovered SARS patients had a poor quality of life 12 years following recovery, and were susceptible to inflammation, tumors, and glucose and lipid metabolic disorders,” researchers wrote.

Doctors like Tsang at Hong Kong’s Princess Margaret Hospital said looking at former SARS patients is potentially instructive. Among survivors of the SARS outbreak of 2003, chronic fatigue and impaired lung function have been found in follow-up studies after two to four years.

“This is so new that I don’t think anyone is able to tell what is the percentage of patients who will recover, what is the percentage of patients who will not recover and have long-term sequela,” said Michelle Biehl, a critical care pulmonary doctor at the Cleveland Clinic in Ohio, using the medical term for chronic conditions after a disease.

Societal Implications
Tracking and figuring out how Covid-19 affects the body even after recovery could inform governments budgeting for social safety nets, doctors that see patients long term, and businesses as they set policies such as sick and disability leave. These issues could be even more crucial as public health officials say there’s a possibility the virus may become a seasonal affliction.

Economies and companies looking to get people back to work will need to understand how and if Covid-19 affects human health in the long run and its scope.

“There is such a wide range in the way the illness affects people. The various stakeholders need solid data to help them understand the breadth and duration of long term effects,” said Jessica Justman, a professor of medicine in epidemiology at Columbia University.