The latest outbreak of COVID-19, which is currently affecting 28 provincial-level regions, is generally under control, and China will continue its dynamic zero-COVID policy, which has proved to be effective against the highly infectious Omicron variant, the National Health Commission said on Tuesday.

Mi Feng, commission spokesman, said during a news briefing that the fast spreading Omicron variant is the principal cause of most domestic outbreaks.

"With the increasing occurrence of infection clusters, the number of new cases has risen rapidly and a growing number of regions have been hit by the virus," he said. "The epidemic situation is severe and complicated."

Lei Zhenglong, deputy director of the commission's Bureau of Disease Prevention and Control, said that as of Monday, the Chinese mainland had registered more than 15,000 local infections in 28 provincial-level regions, amid a fourth wave that has hit its neighbors particularly hard.

He said that the outbreaks in Jilin, Shandong, Guangdong and Hebei provinces, as well as in Shanghai municipality, are still developing and some regions are seeing a rapid increase in new cases.

However, health authorities said that China's dynamic zero-COVID policy — which features a combination of targeted lockdowns, mass testing and rapid isolation — has proved effective in tackling outbreaks of Omicron.

"Local governments are accelerating screening, and the transferring and quarantine of people at risk," he said, adding that the situation is controllable.

Lei added the State Council's Joint Prevention and Control Mechanism has dispatched working groups to at least six provinces to help local governments take more resolute and science-based virus control measures.

According to the commission, China has fully vaccinated nearly 1.24 billion people as of Monday.