World's first vaccine against deadly swine fever nears approval in Vietnam

Vaccines against African swine fever being tested in Vietnam are close to approval, global and US veterinary officials said, in what would be a major breakthrough to tackle the deadly animal disease that regularly ravages pig farms worldwide.

African swine fever has for years disrupted the $250 billion global pork market. In the worst outbreak in 2018-19, about half the domestic pig population died in China, the world's biggest producer, causing losses estimated at over $100 billion.

After decades of failed attempts due to the complexity of the virus, two vaccines co-developed by US scientists being tested in large pilot schemes by Vietnamese companies are showing "very promising" results, Gregorio Torres, head of the science department at the World Organisation for Animal Health (WOAH), told Reuters in a telephone interview.

"We have never been so close to get a vaccine that may work," Torres said, noting the two shots had "probably the highest chances to succeed" and be authorised for sale worldwide.

Both vaccines have received approval in Vietnam for pilot commercial use, now completed. The next step will be nationwide authorisation, the first ever for an African swine fever vaccine, and possible sales overseas.

US agriculture secretary Thomas Vilsack said there was likely to be interest in precautionary purchases in the United States, despite the country having so far been spared from the virus.

"There will be a specific interest obviously," Vilsack said in an interview with Reuters in April, speaking about possible purchases of the Vietnamese vaccines.

The vaccines were tested in Vietnam, where swine fever is a constant threat, because they could not be developed in the US as the virus is not present there.

Since 2021, swine fever, which is not deadly to humans, has been reported in nearly 50 countries and caused about 1.3 million pig deaths, WOAH said in a regular report last week.

Currently there are no major outbreaks, but agribusiness lender Rabobank warned in April that the possible spread of the disease, especially in China, remained among the top risks to the global pork industry.

No safety issues

United States Department of Agriculture (USDA) researchers have reviewed the results of one of the vaccines, NAVET-ASFVAC, which they co-developed with Vietnamese company NAVETCO, a USDA spokesperson said.

After the vaccine showed a high level of efficacy and no safety risks in trials, 600,000 doses were approved for initial sales to pig farmers in Vietnam, of which the first 40,000 "have been delivered without any safety problems," USDA said.

That followed an initial hiccup when use of the vaccine was suspended after dozens of pigs died last summer following inoculations in farms that used the vaccine off-label, USDA said, administering it to hogs that were not supposed to be inoculated, such as pregnant sows.

No problems emerged after deliveries resumed with adequate veterinary monitoring, USDA said.

NAVET-ASFVAC is an attenuated live-virus vaccine, like those used in childrens' routine vaccinations around the world. Use of unlicensed live-virus vaccines in China in past years raised concerns they caused the emergence of new strains of swine fever.

Only limited data are available from China's trials on a live-virus vaccine against swine fever.

The second vaccine tested in Vietnam, AVAC ASF LIVE, which was discovered by US researchers and commercialized by Vietnamese firm AVAC, has been delivered to more pigs than NAVET-ASFVAC under its pilot deployment, but USDA said it had not yet reviewed the data.

NAVETCO, AVAC and Vietnam's agriculture ministry, which is responsible for approval of veterinary vaccines, did not respond to requests for comment.