As stated before if vaccinations work why are you bothered about other birds,surly your birds are immune.To vaccinate you are injecting a mild form of the disease into your bird so it is more likely that it is your birds that are infecting the unvaccinated birds.Vaccination was brought in on political grounds as some european countries were refusing to buy uk poultry. One local fanciers birds caught it when it first started and when he reported it no one was even bothered to reply,i think he lost two birds and the rest were ok.Next year he bred me a team of youngsters and they were fine in fact one of my best ever birds i have raced was one of them,so would i vaccinate ? no way and the last season i flew i bred eighteen ybs flew through to yb national and finished with seventeen.