The acceptability of HIV immunization: examining vaccine characteristics as determining factors.

The acceptance of a future HIV vaccine may be influenced, in part, by the characteristics of the vaccine itself. This study evaluated the relationship of vaccine characteristics to acceptability of hypothetical HIV immunization. Subjects were 549 undergraduates (18-56 years of age); 70.3% were female, and 80.4% were non-Hispanic white. Subjects completed a self-administered questionnaire assessing a series of 12 hypothetical vaccines that varied along the dimensions of efficacy (80 or 50%), cost (free or $300) and social saturation or percentage of the population already vaccinated (10, 50 or 90%). The vaccines were each rated on an 11-point scale ranging from zero ('I will never get this vaccine') to 100 ('I will definitely get this vaccine'), in increments of ten. All three dimensions were significantly associated with probability of vaccine acceptance, particularly vaccine efficacy and cost. The highest rated vaccine (free, 80% efficacious, 90% saturation level) received a mean acceptability score of 83.4, whereas the lowest rated vaccine ($300, 50% efficacious, 10% saturation level) received a mean score of 32.8. The mean acceptability rating across all 12 vaccines was 55.14. These findings indicate the potential importance of considering the influence of vaccine characteristics in future HIV immunization programmes.