African swine fever: Hastily developed vaccines could make outbreaks worse

African swine fever affects both domestic and wild pigs.Photo / Supplied

An epidemic of African swine fever (ASF), which has devastated pig farming in Asia, is currently spreading into Europe and could soon become a threat to the global pig population, could get worse if a vaccine is rushed, say researchers.

In spite of the imminent need, vaccination efforts for ASF have proven unfruitful thus far.

In a Perspective, Dolores Gavier-Widén and colleagues argue that in the rush to develop and deploy an effective ASF vaccine, quick solutions may instead make matters worse.

"The race to develop an ASF vaccine may overshadow comprehensive efficacy and safety testing, thus potentially investing in the wrong vaccine development strategy and in unnecessary use of animals for experiments" the authors wrote.

ASF is a highly contagious and deadly viral disease affecting both domestic and wild pigs.

In 2018, an outbreak in Asia was responsible for the death or destruction of nearly 5 million pigs within a single year – or roughly 40 per cent of the Chinese pig herd – significantly impacting global food markets.

Although there has been some success in using high-containment facilities to control infected swine, the natural movements of infected wild boar populations make efforts to contain the spread of the virus challenging.

Similarly, the development of a successful vaccine for the African swine fever virus (ASFV) has proven difficult.

According to Gavier-Widén et al., the most promising ASF vaccine results have come in the form of live attenuated vaccines (LAVs), which are naturally occurring genetically modified strains of the virus that trigger immunity with reduced virulence.

This form of vaccine could be used in bait for wild boar and administered to farmed animals.

However, previous LAV failures have instead caused ASF-like disease, and even spread the virulent form of the virus further, highlighting essential safety concerns that must be evaluated during vaccine testing and addressed before any solution is deployed.

Read the full Perspective here.