If they don't have it yet they probably won't. I had my dog and my foster that both had it (mine had it twice) and despite my senior girl licking green boogers from my younger Boxer's mouth and nose and eating food he had already put in his mouth and dropped she never got it. Some dogs just have better immune systems than others, or some have already had it and built up the immunities, etc. Same as you getting a cold/flu but your kids or spouse not. As long as it's slowly improving just give it some time and it'll be a distant memory.