Hendra vaccine - a remarkable story

A VACCINE is now on the market for preventing Hendra virus in horses. For various reasons this is remarkable.

While Hendra is quite a nasty disease, it only occurs in Australia and has so far only affected horses in Queensland and northern NSW.

Although its epidemiology is still not entirely understood, the disease is known to be spread by flying foxes. Thus keeping horses and flying foxes apart could easily have remained the only control option for decades to come. There are plenty of uncommon diseases for which there is no vaccine.

What made the difference in bringing the vaccine to market is some outstanding scientific spadework together with the involvement of the Australian division of the world’s largest animal health company, Pfizer.

Soon after the disease first appeared in 1994, CSIRO scientists at the Australian Animal Health Laboratory identified the causative virus and confirmed it was a new species.

It was classified as Biosafety Level 4, a category reserved for the most dangerous and exotic agents posing a high individual risk of aerosol-transmitted laboratory infections, and agents that cause severe to fatal disease in humans for which vaccines or other treatments are not available.

By 2006, with help from some US scientists, they had found that a portion of the virus protein could be used to provoke an immune reaction. That was a very important discovery as it opened the door to the possibility of a vaccine that did not require production of the whole virus.

At that point funding for vaccine development became a limiting factor. Various options were canvassed and the Queensland Horse Council established a special Hendra vaccine development fund.

Things could have remained at that point except that in 2010 Pfizer’s Australian animal health division decided to become involved. The company has development facilities in Melbourne along with considerable experience at developing, formulating and producing vaccines on an industrial scale. In this case its expertise in formulation and adjuvants proved to be especially important.

Pfizer is also familiar with the Australian regulatory system for new veterinary drugs and convinced the regulator, the APVMA, to initially approve the vaccine under a permit rather than require full registration before being released onto the market. That shortened the time to market by one to two years.

It helped that the Hendra virus is fatal to humans, with four of seven people infected dying of the disease so far. State and Federal governments chipped in to help cover the costs of developing the vaccine, while the US National Institutes of Health helped with production funding.

The US interest arose from the fact that Hendra belongs to the same family as Nipah virus, a disease first seen in pigs and responsible for the death of up to 200 people in Malaysia and Bangladesh. Concerns that either could be used maliciously prompted the US military to take it seriously.

The impact of the vaccine on horse owners, trainers, grooms and others who work closely with horses, as well as veterinarians who treat them, may well be life-saving. Since Hendra was first identified, every encounter with a sick horse has been potentially life-threatening. For their own safety, veterinarians have had to adopt quite extreme protection measures when dealing with sick horses. Some have ceased treating horses altogether.

It will also have a substantial impact on the horse industry. Fear of the disease has discouraged some horse owners from taking their animals to events where there is a risk of exposure. And with flying foxes now found to be carrying the virus in all mainland states, options for avoiding it are limited.

But whether Pfizer makes a profit from its investment is another matter. There have only been 31 outbreaks of the disease, resulting in 81 horses dying plus a small number infected but surviving. Even if every horse in the country is vaccinated, the market would be modest. If, as is possible, only valuable horses plus those within range of flying fox roosting areas are vaccinated, it could be tiny.

Nonetheless, the vaccine also appears to be effective at preventing Nipah virus and it, or one like it, will probably be used in those countries where the disease occurs. No doubt it will save lives there too.

And measures to develop a human vaccine against both Hendra and Nipah viruses are moving ahead in the US, with the company Profectus recently awarded a grant to develop the vaccine. Ultimately it will be possible to vaccinate both horses and their carers against the disease.

All because of some remarkable work in Australia and the local division of a multinational pharmaceutical company.

David Leyonhjelm is an agribusiness consultant with Baron Strategic Services. He may be contacted at reclaimfreedom@gmail.com

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Agribuzz with David LeyonhjelmCommentary, news and analysis with agribusiness consultant David Leyonhjelm. Email David at reclaimfreedom@gmail.com

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