Really worried????!!!?

Ok so as everyone has probably heard there is a out break of EHV in Washington (probably other places to). All of the barns in the state are in lock down as is WSU. Im really worried because a friend of mine had her horse up at WSU (that is where it pretty much started) for breeding. That horse has since been at my barn where my horse is several times a week for lessons (the breeding was unsucsessful so they have kept training). Today there were 3 confirmed cases of EHV in my town. So we are on lock down at the barn no horses come in or go out but how else can I help my horse not to get it? He is older he is healthy but Im worried if he gets he might not be strong enough to pull through. And the foal it is only 4 days old. And what are signs of it?