The effects of vaccine characteristics on adult women's attitudes about vaccination: a conjoint analysis study

The number of current and future vaccines for adults has been steadily increasing. Yet, vaccine coverage rates for adult vaccinations have historically been low, and less is known about how adults in the mid-adult age range make vaccine decisions for themselves. The purpose of this study was to assess which vaccine characteristics affect vaccine decision-making among mid-adult women. Adult women, aged 27-55 (n=258) rated 9 hypothetical vaccine scenarios, each of which was defined along 4 dimensions: mode of transmission (STI or non-STI), severity of infection (curable, chronic, or fatal), vaccine efficacy (50%, 70%, or 90%), and availability of behavioral methods for prevention (available or not available). Ratings ranged from 0 to 100. Conjoint analysis was used to assess the effect of relative preferences for the vaccine scenario characteristics on participant ratings of scenarios. The mean vaccine scenario rating was 78.2. Nearly half (40%, n=104) of participants rated all nine scenarios the same, with the majority of those (84%) holding strongly positive views. Conjoint analysis of the other 154 participants who discriminated between scenarios indicated that the main drivers for vaccine acceptability were severity of the disease and the efficacy of the vaccine to prevent the disease. Mode of transmission and availability of a preventative behavioral measure did not play a significant role. Future studies should further assess how women's understanding of severity of the disease and efficacy of the vaccine to prevent disease may be useful for increasing vaccine acceptability.