Karen, don't make yourself crazy.
I know you've been slammed by this stupid virus and I am humbled by what you've been through.
Definitely clean any areas best you can and then...breathe.
At the time we had our Mareks bird in the house, we didn't know what it was. She was a recent rescue who was skinny and after 3 weeks (I tried to let them settle in) we found she was infested with lice. Brought her into the house to bathe (with the other two who came with her) while we had day olds brooding in the next room. Cleaned up the Mareks bird and the very next day she started to have a little stumble, then a wing droop. First we thought she was over run with worms (never saw any) or the lice were so bad it had made her anemic. I wish that had been the case. We started to hand feed her outside. Eventually, she wouldn't even stand up. So she started living in a big dog crate in our kitchen, the brooder room was down the hall. This was January and we have forced air heating. So her air was being circulated throughout the house. Once it was all said and done, I shared this with the two vets we dealt with.
Both said: 1) YES! our chicks in the house were exposed. All but two chicks were from hatcheries and were vaccinated. Two were locally bred and were not vaccinated. They are now a handsome & strong lot of 20 week olds.
2) That the two chickens who arrived with her and our one hen who eventually moved in with the other two immediately after we brought the Marek chicken in....all MUST have immunity as (count my blessings) are all fine. In fact, the health of the other two improved! (sorry if that was confusing. We had one house chicken -- a neighbor's hen that decided we were cooler, and she's right. And two hens who were rescued along with the Mareks bird. They had all been living with or were exposed to Mareks bird -- her name was Liz.
I miss her every day. You get so close to them going through this nightmare.)
For me, we've chosen not to vaccinate. I'm just not up to giving the shot to any new chicks we will hatch and worrying about are the chicks exposed within their first 10 days (I'm not perfect, the dogs are exposed to the chickens, they come in the house, they touch the cats, the cats sneak into the brooder room when we go in, etc.). I'd be doing the same things I'm doing now (biosecurity as in handling the chicks before I work with the older birds, keeping the ages apart, etc). Plus, since we're breeding for our own pleasure and I'm a total sucker, ALL roos have a home here, we're a happily closed flock.
So I'm sorry I can't help anyone who plans to vaccinate. You almost need a "clean room" that has it's own air system and where you take Silkwood showers before you enter to know nothing came in with you (I hear germs can hide in the folds of your ears!). We're looking at the gradual, minute exposure our new chicks must be getting and keeping their stress down as the gradual development of immunity.
I hope knowing how much our chicks were exposed bring some relief. Also, you should know, those birds we rescued came to us by way of the feed store. Of course I kept them posted and they notified the people dealing with the rescue. Since that time they have literally sold over 15,000 chicks (they bragged about it on FB) and continue to get and sell adult birds (chickens, peafowl, ducks, turkeys). So 1) I haven't heard of them having any problems. 2) So if Mareks was at this place, and they get vaccinated chicks...haven't the chicks been exposed before the 10 days are up? I think there is no way to be 100% away from this virus. Just good flock management, supportive nutrition like herbs and ACV and knowing all you can is the best defense we have.
) next year if all goes well. Let's hope that resistance is passed on to the babies. 
