X2Also vaccinating now won't help. It's suppose to be done when they are a day old. Still sounds like wry neck to me as I have had it happen to older birds. Sorry your having to go thru this.
It is a waste of time, money and effort to vaccinate now. It can only be effective if given well in advance of exposure to the wild strains. That usually means in-ovo or by day3 for chicks.
The vaccination is basically in a race with the Mareks in the environment.