Can you vaccinate older chickens for Mareks?

[BackyardBradshaw]

I've got some questions about the Mareks vaccine that I can't seem to find on any of the forums. Wanted to see if anyone had some input:

1) Can you vaccinate hens for Mareks, or only chicks?
2) If hens can be vaccinated, would it harm them if they previously had the vaccination?

We've got some older girls (1yr) that we aren't sure if they've been vaccinated. We are planning on getting more chicks soon, which will be vaccinated. We were thinking of vaccinating them all for good measure, I just don't want to cause any harm by doing so if they had already been treated as chicks.

 

[BackyardBradshaw]

Of course after I post this, I'm finding articles on how you should only vaccinate chicks that aren't older than 36 hours. I do welcome any vaccination information you all can provide though so feel free to share your thoughts. I'm still researching as I'm writing this.

 

[nuthatched]

Mareks vaccine doesn't prevent them from getting or spreading mareks, it just keeps the symptoms down and reduces the chance of dying from it. If vaccinated birds catch mareks, they likely won't die but they'll carry it.

 

[coach723]

The vaccine only works on birds that have never been exposed to the virus. That's why only chicks get vaccinated, before they are old enough to be exposed. They also have to be isolated for at least 2 weeks post vaccine to be sure they are not exposed before the vaccine has time to impact their immune system. Or the vaccine might be ineffective.
As previously stated, the vaccine does not prevent them from getting, carrying or transmitting the virus, it only prevents the formation of tumors in vaccinated birds, reduces mortality in other words. The vaccine doesn't 'cause' Marek's disease, so there is no reason to worry about having some birds vaccinated and some that are not (unless you are dealing with active disease in your flock), many buy vaccinated chicks but do not vaccinate their birds hatched at home. It's also problematic that the vaccine comes in large dose vials (1000 doses) and has to be used up once activated, it has no shelf life. So for most back yard keepers that's a lot of waste. There is a lot of literature on the vaccine, pro's and con's, there tend to be strong opinions both for and against it. Because it's a leaky vaccine (does not prevent the disease, just mitigates mortality) some feel it may be making the virus worse since some birds with disease will live and pass it on rather than die from it. There are articles about that. I'm not taking sides, many people get vaccinated birds. Hope that helps some, you will need to read as much as you can, and then decide what is best for you.
But I wouldn't try to vaccinate your adult birds.
http://extension.msstate.edu/publications/marek’s-disease-backyard-chickens