Zhong Nanshan (Photo:VCG)

China's top epidemiologist Zhong Nanshan said that COVID-19 virus mutations should be closely tracked, and it is important to consider which strain of the virus to use as a vaccine if the virus mutates. He pointed out that the recent cases caused by the new variants in China pose a new challenge in its epidemic prevention and control efforts.

Zhong made the remarks at a press meeting on Sunday, noting that close observations of the effectiveness of COVID-19 vaccines are needed and the health authorities should strengthen epidemic prevention and control in rural areas by introducing more high-tech tools.

China has reported confirmed COVID-19 cases caused by a coronavirus variant that was initially detected in the UK in at least five cities, including Tianjin, Beijing and Shanghai.

"COVID-19 virus mutations should be closely tracked," Zhong noted, stressing that the observations of vaccine effectiveness should be put on the agenda.

Now, a most critical mutation of the virus is occurring in the receptor-binding site of the spike protein, which explains why the novel coronavirus has become more infectious, he said, noting that it is also important to consider which strain of the virus to be used as a vaccine if the virus mutates, he said.

It takes a long time to observe vaccines' protection rate and the key point is seeing how much ability the synthetic antibodies have to kill the virus, he said.

A total of 24 million doses of coronavirus vaccines have been administered in China as of Tuesday, the Chinese Center for Disease Control and Prevention announced on Sunday.

When asked if it was unnecessary for vaccinated people to continue wearing masks, Zhong said "the answer is negative", as it takes at least two to three weeks for the production of antibodies after the first shot and another two weeks to see an obvious protective effect. The risk of infection remains during this period, therefore people still need to take precautions after being injected.

As for the cluster outbreaks in North China's Hebei Province and Northeast China's Heilongjiang and Jilin provinces, Zhong noted that the local transmission in these regions mainly occurred in rural areas due to the weak testing ability there and insufficient knowledge of epidemic prevention among grassroots-level people and medical workers.

He suggested that authorities introduce more high-tech tools and equipment in their epidemic prevention and control work in rural areas, such as mobile testing vehicles that can carry out automatic sampling and testing and produce results within half an hour.

The flare-up of COVID-19 cases in Hebei, Heilongjiang and Jilin will be basically brought under control in February with the strong intervention of the government, Zhong added.

The research that his team conducted with universities suggested that the infection rate may have been reduced by 20 percent to 30 percent after the government upgraded the epidemic control system from level-III to level-II, he said.

The Chinese mainland reported 73 new domestically transmitted COVID-19 cases on Sunday, of which 63 were in Jilin, nine were in Heilongjiang and one was in Hebei, reports said.

As the Chinese Lunar New Year holidays approach, the senior epidemiologist encouraged people to stay home for the holidays and urged authorities to beef up epidemic control efforts in rural areas.