Trial participation and vaccine desirability for Vi polysaccharide typhoid fever vaccine in Hue City, Viet Nam

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Abstract
Objectives To identify demand for Vi typhoid fever vaccine for school‐age children; obstacles and enabling factors for vaccine delivery; and socio‐behavioural factors associated with trial participation and possible predictors of future vaccine acceptance, in Hue City, Viet Nam. Methods Pre‐ and post‐trial surveys of randomly selected households with children aged 6–17 years. Simple multinomial logistic analyses for ratios of relative risks (RRR) and significance on trial participation by demographics and variables related to typhoid fever, vaccination, and pre‐trial experiences with information and consents. Multiple logistic regressions to assess differences in participation based on child's characteristics. Results As many as 62.6% of households let all school age children participate, 10.2% let some participate, and 26.8% let none of their children participate in the trial. Factors associated with all children participating included past use of healthcare facilities (RRR, 0.45; 95% CI, 0.24–0.83), knowledge of vaccines (RRR, 0.17; 95% CI, 0.03–0.86), and perceived causes of typhoid fever (RRR, 0.90; 95% CI, 0.81–0.99). Factors associated with some children participating included utilization of healthcare facilities (RRR, 0.08; 95% CI, 0.01–0.66) and perceived severity of typhoid fever (RRR, 0.64; 95% CI 0.46–0.88). Participation was associated with satisfaction regarding pre‐vaccination information and consent procedures. Children and adolescents were active decision‐makers. Only 14 of 461 (2.2%) respondents would not use the Vi vaccine in the future for their child(ren). Conclusions Inter‐related factors contribute to participation in a clinical vaccine trial, which may differ from desire to participate in a public health campaign. Educational campaigns need to be targeted to children and adolescents, and consideration for assent procedures for minors. Obtaining informed consent may affect trial participation within a social and political system unaccustomed to these procedures.