The role of herd immunity in parents' decision to vaccinate children: a systematic review.

BACKGROUND AND OBJECTIVE Herd immunity is an important benefit of childhood immunization, but it is unknown if the concept of benefit to others influences parents' decisions to immunize their children. Our objective was to determine if the concept of "benefit to others" has been found in the literature to influence parents' motivation for childhood immunization. METHODS We systematically searched Medline through October 2010 for articles on parental/guardian decision-making regarding child immunization. Studies were included if they presented original work, elicited responses from parents/guardians of children <18 years old, and addressed vaccinating children for the benefit of others. RESULTS The search yielded 5876 titles; 91 articles were identified for full review. Twenty-nine studies met inclusion criteria. Seventeen studies identified benefit to others as 1 among several motivating factors for immunization by using interviews or focus groups. Nine studies included the concept of benefit to others in surveys but did not rank its relative importance. In 3 studies, the importance of benefit to others was ranked relative to other motivating factors. One to six percent of parents ranked benefit to others as their primary reason to vaccinate their children, and 37% of parents ranked benefit to others as their second most important factor in decision-making. CONCLUSIONS There appears to be some parental willingness to immunize children for the benefit of others, but its relative importance as a motivator is largely unknown. Further work is needed to explore this concept as a possible motivational tool for increasing childhood immunization uptake.