Default policies and parents' consent for school-located HPV vaccination.

While defaults may encourage some health behaviors, how defaults influence controversial behaviors is not well understood. We examined the effect of two default policies on parents' consent to have their adolescent sons hypothetically receive HPV vaccine at school. A national sample of 404 parents of adolescent sons participated in an online 3 × 2 between-subjects factorial experiment. Factors varied the default consent policy (opt-in, opt-out, or neutral) and the number of vaccines sons would receive (HPV vaccine alone or along with two other recommended adolescent vaccines). Among parents wanting to get their sons HPV vaccine in the next year, consent was higher in the opt-in condition (compared to the opt-out condition) or if other recommended adolescent vaccines would be included. Default policies had no effect among parents undecided about HPV vaccination. Parents' consent for school-located HPV vaccination may be higher when presented as an opt-in decision and other vaccines are included.