Hmm I have not heard much about Marek's being a issue with Pene's . Not that they where fully resistant but maybe a little. They seem to be the healthiest of any of the breeds I have kept with the exception of maybe mixed Easter EggersThey're all blacks too. I'm getting some unrelated chicks next Saturday. They're from the only pair that existed in Missouri before I got mine. He claims there were quite a few big flocks in Northern MO a few years ago and all either died, were sold off or eaten. He said all of his died of Marek's except for this one pair so that tells me they're probably resistant. That's a good thing.
None of my birds have ever been vaccinated regardless of the breed.