Promising African Swine Fever Vaccine No Panacea, Scientists Say

(Bloomberg) -- A promising African swine fever vaccine being developed in the U.S. is unlikely to eradicate the virus, which has ravaged hog herds across Asia and Europe, any time soon.

Although it shows promise, the vaccine is still some years away from being available to farmers, according to experts. Encouraging small-scale pig producers in affected regions to buy and use such a product will also be challenging and limit its potential, they added.

Any vaccine will need to be affordable enough for subsistence farmers to use on their herds to be effective, said David Williams, leader of Emergency Disease Laboratory Diagnosis at the CSIRO Australian Animal Health Laboratory.

The roll out of any ASF vaccine would require the backing of government and non-government organizations and have to be “well resourced, well coordinated and well funded,” Williams said. “We don’t see it being eradicated from China or Southeast Asia without a vaccine.”

The American Society for Microbiology said this week that government and academic experts in the U.S. have developed a vaccine against African swine fever that’s proved 100% effective. Both high and low doses of the vaccine, developed from a genetically modified prior strain of the virus, were effective in pigs when they were challenged 28 days after inoculation, it said.

The experimental vaccine offers complete protection against the strain that’s currently producing outbreaks throughout Eastern Europe and Asia, said Douglas Gladue, principal investigator at the U.S. Department of Agriculture, which developed the vaccine.

Price Matters

A vaccine could be effective in areas where good farm biosecurity measures are difficult to implement, such as small-scale pig producers in low and middle-income countries, said Kachen Wongsathapornchai, regional project coordinator for the United Nations Food and Agriculture Organization’s Emergency Centre for Transboundary Animal Diseases.

The ASF virus has been most devastating for China, the world’s biggest producer of pork that first reported a case about 1 1/2 years ago. Since then, hog herds have been decimated, with its impact ricocheting across global agricultural markets.

There is no commercially available vaccine against the swine fever, which is deadly to pigs but isn’t known to harm humans. The disease was first discovered more than 100 years ago in Africa. In its most virulent form, it can be 100% lethal. ASF infects pigs and wild boars, and outbreaks have been found in eastern Europe, Russia, and across Asia including Vietnam, the Philippines, South Korea and Indonesia.

Immunizing wild boars in Europe using baits could be effective in preventing the spread among herds in that region, said Lucilla Steinaa, the principal scientist leading research on an ASF vaccine at the Kenya-based International Livestock Research Institute. The U.S. vaccine could have a great impact on Europe and Asia, though current outbreaks in Africa are caused by different strains of the virus, she said.

“The disease can most likely be eradicated in Europe and Asia as it was done earlier in Spain if the will and resources are provided,” Steinaa said, adding that a vaccine will need to be “very cheap, or else it will not get adopted.” It could still be four to five years before any vaccine is brought to market, she said.

Dirk Pfeiffer of the City University of Hong Kong echoed the view, saying the spread of the disease is not under control and a commercially available vaccine could still be some years away.

“It’s good that there’s a lot of development going on. It’s a serious issue and we haven’t got a solution,” he said. “There’s a lot more to be done.”

©2020 Bloomberg L.P.

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