Effective messages in vaccine promotion: A randomised trial

Abstract

This paper [1] presents a randomized controlled trial (RCT) comparing four types of messages, designed to promote MMR vaccination among parents of eligible children against a control (non-vaccination related) message, using three outcome measures designed to reflect: (i) misperception that MMR vaccine causes autism, (ii) perceptions about serious side effects related to the vaccine, and (iii) parental intent about using MMR vaccine for a subsequent child. The four intervention messages were: (a) 'Autism correction' which focused on evidence delinking MMR vaccine and autism; (b) 'Disease risks' that presented information about risks associated with measles, mumps, rubella - as well as adverse events associated with MMR vaccine; (c) 'Disease narrative' which presented a case study with a parent describing the experience of her child contracting measles; and (d) 'Disease images' presenting images of children with the three diseases. The investigators conducted online interviews in two phases amongst a cohort of parents believed to represent the population of United States. The authors reported that 'Autism correction' message resulted in the intervention group having significantly lower odds of believing that MMR vaccine causes autism (compared to the control group), but also significantly lower odds of intent to vaccinate a subsequent child. People who received the 'Disease narrative' had higher odds of having perceptions about vaccine side effects. Likewise those who received 'Disease images' had higher odds of believing that MMR vaccine causes autism. None of the four intervention messages consistently resulted in positive attitudes towards MMR vaccine across the three outcome measures.