When effective, the Marek's vaccine just hides the symptoms and does not actually prevent the disease.. The vaccine in and of itself does NOT actively shed live virus or spread it.. but again... MAY hide it if it is present.
According to my current understanding.. it takes at least 2 weeks to set up.
Possible gross picture warning for all included links..
The following link has very detailed information including a section on the vaccines.. I dug around until finding it states 3 weeks..
https://www.backyardchickens.com/articles/the-great-big-giant-mareks-disease-faq.66077/
Other (valid) resources indicate anywhere from 4 days to 4 weeks depending on vaccine type..
This one from Penn state says 4-7 days..
https://extension.psu.edu/mareks-disease-in-chickens
This link from Mississippi state says 2 weeks..
http://extension.msstate.edu/publications/marek’s-disease-backyard-chickens#:~:text=Vaccination is the only method,up immunity from the vaccine.
This one from Freedom Ranger Hatchery.. states at least one week..
https://www.freedomrangerhatchery.c...disease-and-how-to-not-lose-40-of-your-flock/
This link has a graph for efficacy building, though
I'm unable to verify accuracy.. It illustrates just how key proper handling and administration of the vaccine itself is in the role of the efficacy also.
- Day 1 - 30%
- Day 7-14 - 70-85%
- Day 21-28 - 90-95%
https://www.thepoultrysite.com/articles/mareks-disease-vaccine-handling
Maybe find out which vaccine your hatchery or breeder/hatcher is using and see what the vaccine manufacturers or hatcheries recommendations are for "quarantine"..
Please don't let all this discussion and links cause undue fear mongering..
Happy peeping adventures!