Research into an experimental vaccine against African swine fever developed by the Chinese Academy of Agricultural Sciences' Harbin Veterinary Research Institute is progressing well, with larger-scale clinical trials and production tests underway, the Ministry of Agriculture and Rural Affairs said on Tuesday.

Tang Huajun, president of the academy, said since early April, the institute in Harbin, Heilongjiang province, had launched clinical trials for the vaccine candidate in three bases located in Heilongjiang and Henan provinces, as well as the Xinjiang Uygur autonomous region.

Nearly 3,000 commercial pigs were involved and all vaccinated pigs have proved healthy, with no adverse reactions or pathological changes in anatomy. They also did not shed or transmit the virus and the average immunity rate reached over 80 percent, Tang said.

During the environmental release stage, when the vaccine was injected into piglets and sows in different doses, none of the vaccinated pigs had displayed adverse reactions, injuries or miscarriages, according to Bu Zhigao, head of the institute.

The ministry said more efforts will be devoted to accelerating the production testing and expand the scale of clinical trials in the future.