Vaccination is one of the main weapons in the fight against bird flu. However, scientists did not know if vaccination protected only treated birds or had wider benefits.
"Our conclusion is that vaccination of poultry can prevent a major outbreak of highly pathogenic avian flu viruses," scientist Jeanet Van der Goot told Reuters.
Van der Goot and fellow researchers say that vaccination reduces the infectiousness of chickens with avian flu and also the susceptibility of healthy chickens to the virus.
However, they said it could take two weeks after vaccination before transmission to other birds was completely blocked.