Actually, no. Read the label on the Marek's vaccine - it tells you what species and strain is used in the vaccine, it's not the same as what actually causes what we know as Marek's.
And every vet that I've talked to so far (Oregon) has highly recommended vaccinating young birds. It's a vaccine...
Marek's usually hits before or at around 5months of age. If you're worried about a five year old dying of Marek's - don't, I'd be more worried about him dying of old age
The thing is, you can vaccinate older birds, but the vaccination will have no effect if they've been exposed at all to the...