A medical worker takes a swab sample from a woman for COVID-19 nucleic acid test in Nanjing, east China's Jiangsu Province, Aug. 5, 2021. Nanjing launched a fifth round of nucleic acid testing in some areas of the city on Thursday. (Xinhua/Ji Chunpeng)

NANJING, Aug. 6 -- The first batch of six patients who had been infected with coronavirus were cured and transferred to a rehabilitation hospital for further medical observation on Thursday in the east China city of Nanjing, local health authorities said.

China saw sporadic COVID-19 infections in multiple places after some airport-related cluster infections of Delta variant reported in Nanjing on July 20. The city with over 9.3 million residents had 228 confirmed locally transmitted cases receiving medical treatment as of Thursday.

The cured cases will be under quarantine observation for 14 days in the designated rehabilitation hospital and then they need to stay at home for another 14-day self-observation, according to Yang Dasuo, deputy director of the Nanjing Health Commission.

The remaining cases are being treated in Nanjing Public Health Medical Center and all patients are in stable condition, Yang added.

With epidemic prevention and control measures including mass nucleic acid testing, Nanjing has seen a downward trend in its newly confirmed cases, with only one case reported on Thursday.

In the latest wave, 15 provincial-level regions -- out of 31 -- on the Chinese mainland had reported COVID-19 infections, but the situation is generally controllable, according to officials with the National Health Commission on Thursday.