Expectation of Volunteers Towards the Vaccine Efficacy of the Prime-Boost HIV Vaccine Phase III Trial During Unblinding

Abstract A Phase III community-based HIV vaccine trial using the ALVAC-HIV and AIDSVAX B/E prime-boost regimen (RV144) showed a modest vaccine efficacy of 31.2% against HIV acquisition. Participant's understanding of the trial is a key element of its success. This study aimed to understand participant's expectation and response to the overall results of the trial as well after unblinding. Using an open-ended questionnaire, data were collected from 400 participants who came for the unblinding visit. Fifty-three percent received the vaccine and 47% were placebo recipients. The median age was 30 years (range: 22–37). The observed vaccine efficacy of 31.2% was lower than expected by 67.75% of participants compared to higher than expected (by 6%), as expected (by 11.25%), and those with no expectation (15%). A majority of participants (71.5%) were happy and proud, and indicated that it was a good result. The rest were sad or disappointed (22.75%) or acquiescent (5.75%). After unblinding, 67.92% of the vaccine ...