Being vaccinated doesn't prevent the disease. It just hides some of the symptoms.Thank you.
The Golden Comets (we had three; one was killed by a dog in a freak incident, then this one with the euthanasia a few nights ago, and we still have 1) came from a seller in SE North Carolina that buys chicks in bulk from a hatchery, but we're unsure if those chicks were vaccinated, but suspect they likely were.
The rest of our flock has NOT been vaccinated as 70% of them were hatched right here (we only keep about 10 birds in a backyard flock). The few that were not hatched here are 5 and 6 year-old Silkie hens that came from other local flocks over the years but were quarantined prior to insertion in our flock (there are 2 of these); they are as healthy as can be.
I was not aware that Mareks could show up at any time, but being a hatchery chick, I would think this Comet that died was likely vaccinated. The seller bought the chicks in 100-chick lots.