Some patients who have recovered from the coronavirus have been left with a reduced lung capacity – and left gasping for air when walking briskly, according to a report.

The Hong Kong Hospital Authority announced the findings after studying the first wave of patients who had fully recovered from COVID-19, the South China Morning Post reported.

Three people have died of the illness in the former British colony, which has so far recorded 131 confirmed cases. Among them, 74 people have been discharged.

Dr. Owen Tsang Tak-yin, medical director of the authority’s Infectious Disease Centre at Princess Margaret Hospital in Kwai Chung, said that of about a dozen discharged patients examined, two or three were unable to function as they had previously.

“They gasp if they walk a bit more quickly,” Tsang told reporters Thursday, according to the news outlet. “Some patients might have around a drop of 20 to 30 percent in lung function [after recovery].”

Lung scans of nine infected patients at the hospital suggested they had suffered organ damage.

But Tsang said it had yet to be determined whether they would develop pulmonary fibrosis, a condition in which lung tissue hardened and the organ could not function correctly.

He added that patients can perform cardiovascular exercises to improve their lung capacity over time.

Coronavirus patients have been treated with Kaletra, a medication originally used for HIV/AIDS; hepatitis C drug Ribavirin; and interferon, according to the South China Morning Post.