Effects of a web based decision aid on parental attitudes to MMR vaccination: a before and after study.

Objective: To determine whether an evidence based decision aid on the measles, mumps, and rubella (MMR) vaccine changed parents' attitudes towards vaccination.

Design: Before and after study.

Setting: Website promoted through search engines and online parenting and health websites.

Participants: 158 people completing online questions out of 1277 who accessed the website.

Intervention: Evidence based decision aid with text and graphical representation of the possible outcomes of measles, mumps, and rubella diseases compared with MMR vaccination.

Main Outcome Measures: Attitudes towards MMR vaccination.

Results: Significantly more participants indicated they were "leaning towards" vaccination after using the decision aid (39% before v 55% after, P < 0.001). Compared with those who were undecided or "leaning away from" vaccination after using the decision aid, participants "leaning towards" it were more likely to strongly value its potential to protect their children from the serious side effects of disease (98% v 84%) and other children who could not be vaccinated for medical reasons (68% v 25%). Participants with an unfavourable attitude to vaccination were more likely to be very concerned about the rare side effects of vaccination (78% v 57%), have residual concerns about autism and bowel disease (78% v 27%), and anticipate guilt should their child have an adverse reaction (77% v 50%). Those with a positive attitude to vaccination after using the decision aid were also more likely to feel well informed (83% v 48%).

Conclusions: A web based decision aid significantly improved parental attitudes to MMR vaccination. Residual concerns about autism and bowel disease and the rare chance of serious complications remained as attitudinal barriers to some parents.