A medical worker takes a swab sample from a woman for nucleic acid test in Changning district of East China's Shanghai, April 1, 2022. (Photo: Xinhua)

Wu Zunyou, chief epidemiologist at the Chinese Center for Disease Control and Prevention, said that China still can achieve the goal of dynamic zero-COVID.

He told a news conference on Friday that it will take a long time because the Omicron strain is spreading fast and is difficult to detect.

"We need a more sensitive monitoring system to find cases in time ... We especially need the public's cooperation and support," he said.

Lei Zhenglong, deputy head of the National Health Commission's disease control bureau, said that from March 1 to 31, a total of 103,965 local infections were reported nationwide, affecting 29 provincial-level regions.

"Ninety percent of the newly reported infections nationwide come from Jilin province and Shanghai. The epidemic in Jilin is still in the developing stage while the epidemic in Shanghai is expanding rapidly," he told the news conference.