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ASF China: Clinical vaccine trials show safety so far

There are optimistic reports about the African Swine Fever (ASF) vaccine candidate which is being developed and tested by the Harbin Veterinary Research Institute in China: trials have shown positive early results.

The institute is part of the Chinese Academy of Agricultural Sciences (CAAS). The academy shared the outcomes this week, news agency Xinhua reported. Between April and June, clinical trials have been carried out in 3 breeding bases in Heilongjiang province, Henan province and Xinjiang Uygur autonomous region. Around 3,000 pigs received the vaccine.

A pig suffering from ASF – not related to the Chinese research. - Photo: Lina Mur
A pig suffering from ASF – not related to the Chinese research. - Photo: Lina Mur

Gene-deleted ASF virus as basis for vaccine

The initial news about a possible Chinese vaccine broke in March, when an article was published in Science China Life Science. The vaccine uses a gene-deleted ASF virus as a live attenuated vaccine in pigs and it was approved for clinical trials in that month as well. To a large extent, the Chinese work resembled earlier studies carried out by the USDA’s Agricultural Research Service.

No obvious adverse effects

So far, vaccinated piglets have normally grown and developed with no obvious adverse effects, according to the Xinhua news item. No pathological changes have been found in the anatomy of vaccinated pigs, and no obvious differences have been found between the vaccine group and the control group. The overall mortality rate would be below 1%, with no miscarriages in sows or differences in litter sizes, according to Xinhua. The vaccinated pigs would neither be shedding nor transmitting the virus. Tests for the vaccine’s clinical efficacy are still underway, Xinhua wrote.

Read more about ASF in China

More data needed for solid proof

News agency Reuters quoted Dirk Pfeiffer, professor of veterinary epidemiology at City University of Hong Kong. He commented, “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 would become more confident in understanding what the vaccine actually does. We would need to see more data.”