Evaluating the effects of vaccine messaging on immunization intentions and behavior: Evidence from two randomized controlled trials in Vermont.

The effectiveness of vaccines in reducing child morbidity and mortality worldwide relies on public acceptance. However, relatively little is known about the effects of vaccine communication on vaccine attitudes and immunization behavior. Previous research suggests that common communication approaches may be ineffective or even counterproductive, especially among vaccine-hesitant parents. However, these studies typically rely on observational data or self-reported measures of vaccination intention. Using novel research designs, we tested the attitudinal and behavioral effects of messages encouraging vaccination in both a survey experiment conducted among a large sample of parents in Vermont who expressed hesitancy about childhood immunizations and a field experiment among parents whose children were overdue for vaccines. We find that neither a message promoting immunization as a social norm nor a message correcting common misperceptions about vaccines was measurably more effective than a standard public health message at improving parents' attitudes toward vaccines, intention to vaccinate their children, or compliance with the recommended vaccine schedule. Our results highlight the need for more research on approaches to successfully reducing vaccine hesitancy among parents.