FMD Vaccination FAQs
Are there FMD control options other than just stamping out?
Yes. Since the FMD outbreak in the United Kingdom in 2001 when almost 6 million cattle were culled, research into FMD has offered vaccination as a tool to assist stamping out. The FMD outbreak in the United Kingdom in 2001 was the largest in history. The UK eradicated FMD by stamping out the disease, but suffered losses of more than eight billion pounds sterling (approximately A$19 billion); the country’s livestock and tourism industries were devastated as a result. In the same year, Uruguay also suffered an outbreak of FMD. Uruguay’s cattle population was the same as that of the UK and the number of infected herds was almost identical. However, while the UK used stamping out on its own and killed a total of 5,730,000 cattle (with 3,910,000 testing positive to FMD), Uruguay used vaccination to assist its eradication campaign and needed to kill only 6,937 cattle (all FMD positive).The direct cost of the FMD outbreak in the UK was US$4.6 billion, that of Uruguay US$13 million. The total economic impact of the FMD outbreak in the UK was over US$10 billion, that of Uruguay less than US$400 million.
Why are we considering using vaccine in an FMD outbreak?
Emergency vaccination of certain animals under certain conditions is already a component of the current response policy, so it’s not new policy. Vaccinating animals can ‘buy some time’ because it can delay or even prevent further spread of disease from the known outbreak locations. The revised policy will include strategies for expediting the importation of vaccine, and more clearly outline the criteria for the use of emergency vaccine.
What is ‘protective vaccination’ and ‘suppressive vaccination’?
These terms describe different vaccination strategies. Protective vaccination protects the animals from clinical disease or infection; suppressive vaccination suppresses virus shedding from already infected animals. In an FMD outbreak, protective vaccination could be applied as ‘ring vaccination’. This means that healthy animals in a certain radius around an infected premises would be vaccinated to provide a buffer population of immune animals; this would reduce the size of the outbreak. Protective vaccination is most effective when used early in the outbreak and when the disease is spreading rapidly. Suppressive vaccination would involve a selected group of animals within an area already infected. It is literally the animals in the middle of the outbreak that are vaccinated to reduce the amount of virus that these animals are shedding; this reduces the risk of spread beyond the already infected area.
What does ‘vaccinate to live’ and ‘vaccinate to die’ mean?
These terms refer to the fate of vaccinated animals. If vaccination is used as part of an FMD eradication campaign, the options are to allow vaccinated animals to remain in the population and live out their normal commercial lives or to remove them (by slaughter).
How would we use vaccination? For example, would all susceptible animals be vaccinated?
The exact vaccination strategy would depend on the circumstances of the outbreak but the key parameter would always be to quickly and effectively control the outbreak with a view to restoring business continuity.
Why may vaccinated animals need to be slaughtered before they have lived out their commercial life?
Depending on the time between vaccination and infection, vaccinated animals may not show clinical signs, but they may still carry the virus. That is why even those vaccinated animals are ultimately slaughtered. Before successful FMD eradication can be claimed, there needs to be proof that there are no FMD-infected animals left. This is done by laboratory tests of samples taken from animals in the ‘proof of freedom’ phase after the outbreak. However, animals that were vaccinated against FMD will – for a period of time – give a positive test result for FMD, and standard laboratory tests cannot tell whether this is due to vaccination or watery these animals still carry live FMD virus. Therefore, to be on the safe side, all vaccinated animals are slaughtered as a default. While this approach should ensure that there are no infected animals left, it can result in the need to destroy animals that would otherwise have avoided destruction in a conventional stamping-out campaign without vaccination.
What would need to happen to allow vaccinated animals to live out their commercial lives?
If animals are vaccinated against FMD, they will – for a period of time – give a positive result in blood tests. Standard tests cannot tell the difference between a positive result due to vaccination and a positive result due to actual FMD infection, buts special tests can differentiate infected from vaccinated animals (therefore called ‘DIVA’ tests).Before successful FMD eradication can be claimed, there needs to be proof that there are no FMD-infected animals left. This is done by laboratory tests of samples taken from animals in the ‘proof of freedom’ phase after the outbreak. Animals that were vaccinated against FMD will – for a period of time – give a positive test result for FMD; DIVA tests can tell whether this is due to vaccination (in which case the animal is allowed to live because it presents no risk) or infection (in which case the animal is slaughtered).
Does Australia have FMD vaccine available?
In Australia, governments and livestock industries have invested in FMD vaccine supply arrangements. A supply contract with a commercial manufacturer has been secured over 5 years (ending in 2014) to provide 500 000 cattle-equivalent doses of any of nine FMD strains within 7 business days of notification. This number of doses has been calculated to be sufficient in the early stages of a response but will be supplemented by further purchases if needed.
If we vaccinate animals, won’t that delay our international market access?
No. Despite the World Organisation for Animal Health (OIE) guidelines on recovery of a country’s FMD-free status following an outbreak (i.e. 3 months following stamping out vs. 6 months following vaccination without compulsory slaughter-out of vaccinates), the reality is that recognition of freedom by trading partners is likely to take much longer. We can assume that it will take at least 18 months for re-opening of US and Asian markets, regardless of whether vaccination is used to assist the eradication effort.
Isn’t it true that vaccinated animals can still be infected?
Yes. While FMD vaccines will protect animals against clinical disease, they will not necessarily entirely and in all cases prevent infection. However, vaccinated animals that become infected shed less virus than unvaccinated animals.
If vaccinated animals can still be infected, isn’t it safer to slaughter them after the outbreak?
These days, Australia has the technical capacity to differentiate infected from vaccinated animals by laboratory testing, so that vaccinated animals that are not infected can be allowed to live out their commercial risk without jeopardising our FMD-free status.