On-farm flu vaccines

On-farm vaccination against bird flu is “probably coming”, but not yet, says the Scottish Government’s chief veterinary officer, Sheila Voas.

Speaking to The Courier this week, she described vaccination as a really interesting development, but stressed that the options available weren’t yet at the stage where they could be brought into commercial use, either this year or next.

Ms Voas also explained why she believes the time still isn’t right for Scotland to introduce a poultry housing order to combat bird flu, despite NFU Scotland having called for such a move more than a month ago.

On the vaccination question, she said using

vaccines goes against current rules controlled by the World Organisation for Animal Health (WOAH), measures that would prevent vaccinated birds from being traded, sometimes even including a trade ban on products from vaccinated animals.

“This was discussed by WOAH at a meeting I attended in Scilly in October, when the agenda included looking at the science involved and the case for changes to be made so that vaccination would, in future, become an acceptable control method,” said Ms Voas.

While this might remove some of the concerns that people may have about vaccination, there were still practical problems to be considered, given that the bird flu virus, like human

flu viruses, changes rapidly. Strain changes therefore mean an effective vaccine one year may not provide protection in the following year.

“Also, to secure good protection in birds, you would need two injections,” she said, pointing out the life of an average broiler chicken was only a matter of weeks, making two injections “not feasible” for all producers.

Another practical consideration was that vaccination would have a suppressive rather than preventive impact on the virus.

Vaccinated birds might still get infected, therefore, they just wouldn’t become as sick as is currently the case or shed as much virus.

“The concern would be that vaccinating birds

could mask the problem, leading to bird movements enabling the virus to spread even further,” said Ms Voas.

She added that while the vaccination solution was “really very interesting”, it was going to take considerable work to get the vaccine option to a stage where it would be useful.

Turning to the housing decision, an option which has already been taken in England, the chief vet said this remained a “balancing act” as regards the control of bird flu in Scotland.

“We are constantly monitoring a whole number of different sources of information regarding this issue,” said Ms Voas, maintaining that the time wasn’t right for housing to be applied to Scottish poultry.

In England and Wales, officials are looking at 450 cases, however – so 19 in Scotland is a small percentage

“Looking at our cases, we have had 19 wild bird confirmations so far, although that number changes every day.

“That is 19 different places where infected wild birds have been picked up. In England and Wales, officials are looking at 450 cases, however – so 19 in Scotland is a small percentage.

“We also take account of international disease monitoring, especially whether or not cases are moving closer to our border. Currently, not much is being seen in either Northumberland or Cumbria.”

Wild bird migration routes are also being monitored, based on the fact that the virus tends to be spread by migrating waterfowl.

In looking at such routes, as they are operating currently, these are seen as remaining different to those bringing larger numbers of wild birds into southern areas of the UK.

“We also look at the epidemiology attached to infection cases in Scottish poultry,” said Ms Voas, adding that this involves assessing if an on-farm case is linked to the existing disease or can be traced to a new introduction from a significant wild bird population.

“We also look to see if farm birds were housed at the time of their infection or were free range.

“There are, as such, a huge number of things that all need to be put together to come to an opinion about whether housing is justified or useful.”

AVIAN INFLUENZA: Bird flu has been wreaking havoc south of the border as the Scottish Government monitors the situation up north.

CHIEF VETERINARY OFFICER: Scotland’s top vet Shiela Voas, bottom left, has said that on-farm vaccinations against avian flu – which is currently leading to some shops rationing their eggs and to culls of festive turkeys – could be a potential future tool to fight the disease.