UK pig farmers have welcomed a significant breakthrough in the fight against African Swine Fever, as scientists trial a promising new vaccine.

However, industry experts have urged the UK not to slacken defences at its borders while waiting for a vaccine to become commercially available, warning that the disease has the potential to cause ‘devastation’ if it reaches these shores.

The virus continues to sweep across Eastern Europe and Asia, where it has already resulted in the deaths of around a quarter of the world’s pig population. Statistics from Rabobank estimate that China’s pig herd, typically numbering around 440 million, has declined by 55% in 2019 alone, and neighbouring Vietnam has lost 7.5 million pigs, equating to 21% of its herd.

Scientists from the Pirbright Institute have now created what is known as a vectored vaccine by inserting eight ASF virus genes into a non-harmful virus, known as a vector. In trials so far, 100% of pigs immunised with the new vaccine were protected from a fatal strain of ASF Virus, although clinical signs of the disease did develop. Further development is needed, but if successful, this vaccine would enable the differentiation of infected animals from those that have received a vaccine, which would allow vaccination programmes to be established without sacrificing the ability to trade.

Head of Pirbright’s ASF Vaccinology Group, Dr Chris Netherton, commented: “Demonstrating that our vaccine has the potential to fully protect pigs against ASF is a huge step in our vaccine development programme. We have already begun work to refine the genes included in the vaccine to improve its effectiveness and provide more protection.”

Although there has not been an outbreak of ASF in the UK, producers have been on high alert for some time.

“This is potentially fantastic news for Scottish pig producers, as without a doubt, ASF is the single biggest threat hanging over our industry – it dwarfs Brexit and Coronavirus,” said chief executive of Scottish Pig Producers Andy McGowan.

“However, we are sometime away yet from a commercial vaccine being launched and as it stands, we do not have the tools to deal with it. The disease hasn’t reached the UK yet, but it poses a huge threat if it did, as mortality rates would be extremely high. You would have to cull out the whole herd and leave it empty for 12 months and that would be the end for most pig businesses,” he warned.

Mr McGowan pointed out that the industry could be in for a long wait, as the vaccine has yet to be scaled up to meet demand – and noted that it should be delivered first to those facing very real problems in Asia, rather than prioritising those who would use it ‘as an insurance policy’.

Pig farmer and NFUS pigs committee chair Jamie Wyllie added: “There is a general feeling that ASF could become almost endemic in mainland Europe if controls are not found. The possibility of an effective vaccine gives real hope that the spread of this disease could be controlled, and free areas protected from the devastating impacts of this disease,” he continued.

“But any vaccine should be treated as the final defence in the fight against the disease with vigilance at the border and good biosecurity to prevent it entering the UK. We cannot use the promise of a vaccine as a time to slacken our defences at the border and lower our biosecurity. Our first line of defence must still be vigilance and biosecurity,” he urged.