GUANGZHOU -- China is on its way to developing vaccines against the novel coronavirus variants, China's top epidemiologist Zhong Nanshan said on April 23.

Zhong delivered a speech via video at a high-end medicine forum of the Chinese Academy of Engineering (CAE) held in Guangzhou, the capital of Guangdong Province. He said the virus variants had become a principal contradiction that needs to be resolved by vaccine development to realize individualized and precise prevention.

"This is a world topic. If one or two parameters or comprehensive indicators are found which could be widely adopted, it would be helpful for vaccine development," he said.

Zhong said a key to China's success in precise epidemic control lies in preventing "human-to-human" transmission. "It is through timely screening and timely quarantine that we have succeeded in controlling the epidemic," he said.

The CAE academician Chen Wei, leader of the research team that has developed a recombinant vaccine requiring only one shot, said protection would increase if another dose of their vaccine is administered six months apart.

"The efficacy would improve from 60 to 70 percent to over 90 percent, with the second shot as a boost," said Chen, also a researcher from the Institute of Military Medicine under the Academy of Military Sciences.

She said such a fortified procedure is advised overseas for the vaccination.