Vaccinated Chicken with Unvaccinated Flock?

[CozyDia]

Is it alright to have vaccinated chickens with unvaccinated ones?

My flock of 4 are all unvaccinated. I was thinking of purchasing some pullets from a breeder online. The breeder is NPIP/AI/PT certified and vaccinates everything. I'm afraid that purchasing a vaccinated chicken might introduce Marek's to my environment and harm my existing flock, so I'm hesitant on purchasing.

I checked older threads about this topic, but it seems to be mixed. Any insight on this would be appreciated!

 

[Kiki]

I'd guess they vaccinate because they already do have the disease in their flock.
It is highly likely the birds you buy will have it too.
Don't buy from them unless you are ready to deal with sick birds.