Thanks for the great information! Do you think most people vaccinate?
I don't vaccinate and I am careful not to get birds that are vaccinated or from vaccinated flocks. I understand people vaccinating their own closed flock but if any of those birds were to leave a vaccinated flock they have to be presumed diseased because they are asymptomatic and will therefore infect other flocks without ever showing symptoms. I need to know my birds are disease free and not carriers. The best way to start an epidemic is to transfer exposed asymptomatic birds into as many flocks as possible.
My daughter used to play a game where the goal was to infect the entire planet with a lethal virus. If carriers show symptoms it is possible to track the spread of the disease and stop it from spreading further but without symptoms the virus will spread uncontrolled until it wipes out everyone on the planet.
I have heard that the vaccine will cause vaccinated birds to shed the virus in feather dander without ever showing symptoms in quarantine. This is part of the reason I will not go to poultry shows, it is not worth the risk for me. My flock is free of disease but if a bird were to get infected by wild birds, etc. then I would want to know and prevent it from infecting other birds.
There are many forms of the virus and not all are fatal but I would rather quarantine and cull a sick bird than to infect healthy birds. I was advised to breed for resistance to disease so that is what I do. If my birds ever got sick I might have losses but at least I would not be causing losses in other people's flocks.
I am not judging people for their choices, it is just a good idea to know the long term consequences before making a choice that carries consequences for others. If people ask me if I vaccinate our chickens, I worry that they could expose my birds to vaccinated carriers and I would rather they not even step foot on my property because they could be carriers themselves by transporting dander on their shoes or clothing. I would prefer to lose business than to lose our birds.
That being said, ducks can be carriers of chicken diseases because they are asymptomatic as well. If ducks have been around vaccinated chickens, I don't want to risk bringing them on my property either. Fortunately our best means of biosecurity is hatching our own eggs to replenish our flock over time so I don't need to take unnecessary risks. If my ducks were carrying any chicken diseases, my flock would be symptomatic so at least I could take appropriate measures to isolate and cull infected birds.
With natural immunity my birds can be exposed to risk factors but their immune system would keep them healthy without spreading any diseases. They pass this immunity on to their offspring through their genetics so hopefully that will keep them healthy for many generations.