Public service announcement: Wash your hands

Flu outbreak in three Boston hospitals prompts the reminder to wash our hands over at Running a Hospital. I've been doing the twice-through "Happy Birthday" while washing my hands since seeing a sign in a client's bathroom.  In all their bathrooms. Sing it twice, the signs say, above a drawing of hands washing. What I've noticed: next person to the sink washes her hands longer, which causes person after her to do the same. What's the antonym to contagious? This is it.