These findings were supported by experimental data showing that several immune suppressive viruses have the ability to weaken the immune protection in vaccinated chickens. With a weakened immune defence, the chickens are vulnerable to avian flu virus.
This information indicates that current vaccination programmes alone cannot guarantee control of avian influenza in commercially farmed chickens, because various immune suppressive viruses are widespread in chicken farms and have the ability to make the chicken vulnerable to avian flu even after vaccination.
The professor commented that the prevalence of immunosuppressive virus infection in chickens is not well known and should be studied in more detail. There may be a need for a new vaccination strategy targeting a range of viruses in order to control avian flu, he said.