There is an ongoing debate over the wisdom of vaccinating poultry against the H5N1 virus. China, Vietnam, Indonesia, and Egypt (all H5N1 hot zones) all rely heavily on vaccination programs.
Most of the world, however, believes that vaccination is, at best, a stop gap measure.
That vaccines don't always prevent infection, but may hide symptoms in infected birds, which allows the virus to spread.
Outside of Asia, and Egypt, most countries employ culling as their preferred method of control.
For countries such as China and Vietnam, however, the advice to destroy badly needed food stocks - such as poultry - is a hard sell.
Culling is also more difficult when dealing with millions of small poultry holdings, such as backyard coops, as opposed to larger commercial enterprises.
The OIE (World Organization For Animal Health) has issued a new press release (hat tip Ironorehopper on Flutrackers) that reiterates their strong recommendation that humane culling be employed to control avian influenza, and advising that vaccines should only be used as a temporary measure.
We've recently seen reports of falsification of the number of poultry vaccinated in Vietnam (see Vietnam: Complacency Spreading Bird Flu), and multiple reports suggesting that some vaccinated poultry may be infected with H5N1 but are asymptomatic.
Some recent reports on asymptomatic poultry include:
Zhong Nanshan On Asymptomatic Poultry
Bird Flu Symptoms Changing In Indonesia
Hiding In Plain Sight?
The OIE report below also cautions that vaccination programs must use `appropriate methods, particularly the use of a permanent cold chain.'
In other words, the vaccines must be kept refrigerated. And in many countries, particularly in remote rural areas, that may not be possible.
While the OIE concedes that some nations may require the use of vaccines for `several years', they strongly urge that countries move away from that program and towards the more conventional culling policy.
Their so-called `exit strategy'. Something which a number of nations do not, as yet, appear to be moving towards.
The take away message here is: it is not recommended to use vaccination as a long term control measure since very often it contributes to hide the presence of the virus.
This from the OIE Newsroom.
Avian influenza and vaccination: what is the scientific recommendation?
The OIE repeats critical requisites for best use of vaccination in birds and for a systematic exit strategy
Paris, 4 March 2009 - Highly pathogenic avian influenza H5N1 has been eradicated in poultry in most countries where it had appeared but remains entrenched in a few countries which may put the whole planet at risk.
The OIE strongly reaffirms that eradication of the disease in poultry must go through early detection and rapid response mechanisms in front of any outbreak and through the slaughter of infected or in contact birds, using OIE standards for humane slaughter.
Countries where national veterinary services do not comply with OIE standards on quality are often not yet capable to detect nor to respond rapidly to massive avian influenza outbreaks. In these cases, vaccination should be systematically used as an intermediate control tool until the Veterinary Services comply with the relevant OIE quality standards.
There is a need for good veterinary governance enabling national animal health systems worldwide to better prevent, detect and control emerging infectious diseases. To achieve this, the OIE has created a “Tool for the Evaluation of Performance of Veterinary Services” (PVS) designed to evaluate national Veterinary Services’ compliance with OIE standards of quality, democratically adopted by its 172 Members. This is a key lever for providing practical help for Veterinary Services of all countries to converge, achieve compliance with OIE standards and put in place good governance of their structure and their operating procedures.
After a PVS evaluation Members can request the OIE to carry out a follow-up mission designed to provide advice and assistance to fill the possible gaps of their national veterinary governance.
The use of vaccination could last several years; however it will only be effective if it is applied to all poultry (chickens, hens, ducks, turkeys, geese, quails…) and through appropriate methods, particularly the use of a permanent cold chain. Vaccines should be produced in accordance with international quality standards prescribed in the OIE manual of diagnostic tests and vaccines for terrestrial animals.
As soon as national Veterinary Services are fully operational for early detection and rapid response using biosecurity measures in infected premises vaccination must be stopped; it is not recommended to use vaccination as a long term control measure since very often it contributes to hide the presence of the virus.
Any vaccination campaign must include an “exit strategy” i.e. a return to classic disease control measures.