BEIJING (Reuters) – A Chinese vaccine against African swine fever appears to be safe in clinical trials now underway, the official Xinhua news agency said on Wednesday, a step closer to preventing one of the world’s most devastating livestock diseases.

Progress on the vaccine is being watched by pig farmers in China and around the world, with no cure or vaccine now available against African swine fever.

The disease, which kills almost all pigs infected, has devastated the huge hog herd since arriving in China in 2018, and is still killing pigs there and elsewhere in Asia.

In a paper published in March, Chinese researchers at the Harbin Veterinary Research Institute, part of the Chinese Academy of Agricultural Sciences (CAAS), said a live attenuated vaccine they had developed was safe and effective against African swine fever in laboratory tests.

Clinical trials were approved in March and have been underway since on 3,000 pigs in three locations, said Xinhua, which cited a CAAS news conference.

The three farms in the northeastern province of Heilongjiang, the far western region of Xinjiang and the central province of Henan began testing the vaccine in stages from April to June.

CAAS added that it was running clinical trials to test the effectiveness of the vaccine. Such trials are a critical step in proving its value, experts say.

“To know whether it works, it needs to be tested in an environment where you’d have all the different circumstances, like different types of farm and densities, and then you’d become more confident in understanding what the vaccine actually does,” said Dirk Pfeiffer, a professor of veterinary epidemiology at City University of Hong Kong.

“We’d need to see more data.”

Until now, vaccinated pigs have proved healthy, Xinhua said, with no miscarriages in sows or differences in litter sizes, when compared to a control group. The vaccinated pigs are neither shedding nor transmitting the virus, it added.