Validation of the Vaccination Trust Indicator (VTI) in a multi-country survey of adult vaccination attitudes.

Improved uptake of adult vaccinations could substantially reduce the burden of infectious disease worldwide, however very few countries achieve high coverage of recommended adult vaccinations. Vaccine hesitancy is an important driver of low vaccine uptake among adults but no measure currently exists to capture general vaccination attitudes in this population accurately and efficiently. We utilize data from two surveys of adult vaccine attitudes and uptake conducted in fifteen countries to evaluate the Vaccination Trust Indicator (VTI). The VTI is a six-item measure intended to capture general vaccine attitudes. We utilized multivariable logistic regression to examine the association between VTI scores and self-reported receipt of the seasonal influenza vaccine, receipt of a tetanus toxoid-containing vaccine and intent to receive the flu vaccine in the next season. In the five countries with self-reported vaccine receipt data, we found that a ten-point increase in VTI score was associated with a 50% increase in odds of influenza vaccine receipt (OR = 1.55, 95% CI = 1.48, 1.62) and 25% increase in the odds of tetanus vaccine receipt (OR = 1.26, 95% CI = 1.21, 1.30). Strong associations between VTI score and vaccine receipt were found in each country except China. A strong association between VTI score and intent to receive the influenza vaccine was found in all fifteen countries. The VTI is a promising tool for assessing adult immunization attitudes with clear and immediate uses for immunization programs globally.