No you can not vaccinate for either any more/at this age. Both need to be done at hatch and the Marek's vaccine doesn't actually prevent the disease.The surrounding counties have had it from what the vet had mentioned.
She hasn’t been vaccinated yet. This is a dumb question, but is this something we can do early on vaccinate for coccidiosis and mareks? If so, I need to do it asap with the others. My local vet gave me the numbers to 10 other vets that may see poultry, none of them did, but they did refer me to the Texas wildlife/state vet that called me. They are the ones that are wanting to come out and check for AI and also Mareks I believe is what they said. They did tell me to bag her and put her in a fridge or cooler, so when I get home if she’s gone I’ll be doing that for the test on Monday and I’ll be looking at the link you posted for a necropsy. I really appreciate all of your advice and input. Thank you for that!
You are going to get a crash course in chicken diseases.
You do what ever you can't to prevent them from showing up in your flock because they don't go away.
Do not buy birds from anyone on Craigslist or another "backyard" breeder and you most likely won't have to ever deal with any disease.
Most people bring disease home when they are adding to their flock because they didn't know about disease and didn't realize they were buying sick birds to begin with.
This is why I asked you where you bought your birds.
You are less likely to buy sick birds from a major hatchery.