BEIJING (BLOOMBERG) - China is studying if it is necessary to give booster Covid-19 vaccine shots to vulnerable groups such as the elderly, people with underlying diseases and those who work in high-risk areas.

There is not enough evidence yet to suggest that a third shot is needed for everyone, Mr Wang Huaqing, an expert with the Chinese Centre for Disease Control and Prevention, said at a press briefing on Saturday (July 31).

The country recorded 328 new locally transmitted cases in July, almost equalling the amount of cases reported in the previous five months combined, National Health Commission spokesman Mi Feng said at the same briefing.

The virus being transmitted currently is mostly the Delta variant, but China's virus control measures are still effective against it, Mr Mi said.

Mass vaccinations alone cannot contain the spread of the Delta strain, and must be complimented with stringent curbs such as social distancing and the wearing of masks, said Dr Shao Yiming, a researcher with the Chinese Centre for Disease Control and Prevention.

That's the lesson from many developed countries, where cases are rebounding after the authorities eased Covid-19 restrictions when they reached a high vaccination level, he said.

The government will also step up its work on vaccinating the elderly and teenagers, National Health Commission official He Qinghua said.