Beijing's subway has dropped mandatory mask requirements for travellers, local media reported on Sunday, days after a Chinese health expert said the threat of COVID-19 to humans is no longer at a serious level.

The mask move is in line with broader measures by China, which said last week it was now no longer mandatory to wear face masks when using public transport, according to state media.

"It's as if an era has passed," a user said on China's popular social e-commerce app Xiaohongshu, as social media was abuzz with news of the rules being eased.

Staff at a Beijing subway station tore down signs reminding people to wear masks, Beijing Daily reported.

The pandemic is nearing its end, based on World Health Organization data, said Wu Zunyou, chief epidemiologist at the Chinese Center for Disease Control and Prevention, according to the China Daily.

China, which dismantled its strict COVID rules in December, said the latest official data indicated the COVID positivity rate went up slightly in early April, according to the Global Times. However, respiratory specialists said it was unlikely China would experience another big wave of infections nationwide.

China has declared victory over COVID several times, highlighting the government's response and handling of the pandemic.

Some people on social media voiced concerns over the relaxation of mask rules, saying the virus remains a threat.

"Let's hope there will not be a second wave of infections," a user on China's Twitter-like social media Weibo site said.

Masks are optional on public transport and in supermarkets, movie theatres and other indoor places with large gatherings, Xinhua news reported.

Masks remain mandatory when a person has tested positive for COVID or is displaying symptoms, during local outbreaks and in medical institutions and nursing homes, the report said.

Chinese cities have been scrapping mask mandates for several weeks, including Hong Kong, which ended mask requirements on March 1.