About 14 percent of patients who recovered from the novel coronavirus and were discharged from hospitals in southern China's Guangdong province were tested positive again in later check-ups, according to the local health authority.
A positive test suggests the recovered patients may still carry the virus, adding complexity to efforts to control the outbreak.
There is no clear conclusion on why it happens and whether such patients could still be infectious, said Song Tie, deputy director of the Guangdong Centre of Disease Control And Prevention (Guangdong CDC), at a Tuesday briefing.
According to the preliminary assessment, experts believed the patients are still recovering from lung infections and have yet to be fully healthy, according to Song.
According to the latest treatment guidelines for the COVID-19 issued by the National Health Commission, patients can be considered recovered and released from hospital when their throat or nose swabs show up negative in two consecutive tests, with a CT scan indicating no lung lesions, and when they have no obvious symptoms such as fever.
The guidelines suggest recovered patients should monitor their health and limit outdoor activities for two weeks after leaving the hospital, and check in for retesting in following weeks.
Some patients' test results returned to positive in the follow-up checks, said Li Yueping, director of the intensive care unit at Guangzhou No 8 People's Hospital at the briefing.