A staff member checks the packaging quality of COVID-19 inactivated vaccine products at a packaging plant of the Beijing Biological Products Institute Co., Ltd. in Beijing, capital of China, Dec. 25, 2020.Photo:Xinhua

China's top medical advisor Zhong Nanshan urged speeding up research on COVID-19 vaccines to fight the mutating coronavirus strains, as COVID-19 variants have been reported in the UK, Brazil, South Africa and India. 

China's inactivated vaccines, developed by Sinopharm and Sinovac, showed declined protection rate against the B.1.351 variant first discovered in South Africa, Zhong said at a medical forum in Guangzhou, South China's Guangdong Province on Saturday.

There are more than a thousand variant strains circulating worldwide, reports said. Some strains, including those first detected in the UK, South Africa, Brazil and most recently India, raised wide concerns over their stronger infectivity and the possibility of dodging immunity. 

Zhong said that China is stepping up research on vaccines against mutated strains. 

Vaccines normally see weakening efficacy against virus mutants but still protect people, experts said, noting giving an extra dose could help prevent the mutated virus from escaping immunity.

As the virus mutates, some antigen characteristics may change and result in a weaker response of the vaccine-stimulated antibodies, a Beijing expert on immunology who asked not to be named told the Global Times on Saturday.

An extreme but still possible case is that all the antigen characteristics that can prompt immunity disappear at the end as the virus keeps mutating. That is the moment new vaccines are required, the expert said.

Vaccines with efficacy above 50 percent are deemed effective by the World Health Organization (WHO), Feng Duojia, president of the China Vaccine Industry Association, told the Global Times on Saturday. 

Feng said that the WHO will issue a warning to the world when it detects major mutations of the virus and the mutated strain is prevailing. Countries can adjust their vaccine development production according to it. 

Apart from producing new vaccines, Feng also suggested giving booster shots to fight the new variants. Booster shots will also improve the immunity of those who have a weak immunity response, Feng said.

Sinovac and Sinopharm have not yet responded to Zhong's remarks as of press time Saturday. At a press conference on March 28, the companies said that they have started vaccine research on relevant strains.