No known variants of the novel coronavirus have been found to weaken the effectiveness of the four homegrown vaccines approved for use in China, a senior drug and vaccine development expert said on Monday.

However, active planning and preparations must be devoted to coping with the risk of accumulated genetic mutations, which over the time might reduce immune responses evoked by vaccines, Wang Junzhi, an academician with the Chinese Academy of Engineering, said during a news conference.

"Chinese researchers are closely monitoring emerging variants, and collecting and testing them against vaccines in a timely manner," he said.

"Meanwhile, we have built a strong vaccine development platform and are pushing for research into new generations of vaccines, so that in case emerging variants prove to weaken immune responses, we can develop new doses against them as fast as possible," he added.