Choose Life This Day
Yes I have heard of people that live in the same household not catching it from each other. The same way when I or my partner get a cold that sometimes the other gets it and others they do not. Clearly it is infectious but some people seem more susceptible to catching it than others but no one knows who or why. However it does raise questions looking at the picture of them so close together if one caught it at that party and the other did not and also is anyone else there infected. I somehow doubt we will ever know.
Yes they do. Infectivity and severity are intimately sensitive to pH.