Vaccination can be used either as a tool to support eradication or as a tool to control the disease and reduce the viral load in the environment.
In countries where the virus has become endemic, vaccination is an appropriate mechanism for reducing its spread, but vaccination may be the answer in one country and not in another.
It is important to state that disease awareness, early detection and notification, are pre-requisites of effective control programs aimed at eradication of the infection in poultry. Biosecurity is an essential part of the control of avian influenza and must be given due importance in planning of control measures.
Early stamping out remains thepreferred control option for an outbreak of Highly Pathogenic Avian Influenza (HPAI) and should be used on all flocks exhibiting clinical disease. It is important that vaccination alone is not considered to be the only and easiest solution to the control AI.
A suitable option
As it may not be either desirable or feasible to proceed with massive culling in some situations, vaccination is considered a suitable option. The rationale being that vaccination reduces susceptibility to infection and shedding.
It is therefore, an appropriate tool to reduce the number of new outbreaks and viral load in the environment, and thus is expected to contribute to other measures to reduce the potential for spread to humans.
A mix of measures
Controlling the disease through vaccination may be a prelude to eradication. Stamping-out and vaccination are not mutually exclusive, and the mix or sequence of measures may differ between production systems and stages of a control program. Vaccination should be used in a strategic manner, with careful consideration to choice of target groups and areas based on the outcome decided by the national authorities.
The “Differentiation of infected from vaccinated animals” (DIVA) approach is recommended since it will still allow to verify virus circulation in poultry. Another method consists in regularly monitoring unvaccinated sentinel birds in vaccinated flocks.
These two methods and the search of virus in specific places such as markets enable the detection of field exposure in areas where vaccination programmes are carried out.
The use of vaccination must be coupled to surveillance to promptly detect any change in virus properties and must be carried out with appropriate products manufactured in compliance with OIE international standards.
Source: FAO/OIE Global Strategy for the Progressive Control of HPAI