Reported willingness to participate in a hypothetical HIV vaccine trial and its translation to actual participation among healthy adults-Experience from Kenya

PLoS One. 2018 Nov 2;13(11):e0206656. doi: 10.1371/journal.pone.0206656. eCollection 2018.


Objective: To evaluate initial reported willingness to participate in a hypothetical HIV vaccine clinical trial and actual participation of volunteers in a longitudinal observational study.

Methods: We recruited HIV negative male and female volunteers aged 18-45 years into a longitudinal observational study at KAVI-ICR Kangemi in Kenya, to serve as a pool from which to draw participants into a phase I HIV vaccine clinical trial. A structured questionnaire was used to collect information regarding willingness to join a HIV vaccine clinical trial in the future. Study follow-up visits were every 6 months.

Results: A total of 105 participants were screened and 100 (M46:F54) were enrolled into the observational study. Ninety- four per cent of those enrolled expressed willingness to participate in a future HIV vaccine trial. Altruism and desire to learn the body's response to the vaccine were the most motivating factors at 40% and 25% respectively. At the onset of a 40-person phase I HIV vaccine trial, 86 observational study participants who had previously expressed willingness to participate were contacted but only 26 (30%) came for information. All 26 consented to participate and after screening for eligibility, 24 were eligible. Of the 24, 15 were enrolled. These numbers were not adequate; hence the vaccine trial employed other recruitment methods to meet the deficit.

Conclusion: Observational "pools" of cohorts may not provide adequate number of participants into vaccine clinical trials even if they report willingness; therefore supplementary recruitment methods such as direct community recruitment, passive approach, and snowballing need to be in place.

Publication types

  • Clinical Trial, Phase IV
  • Observational Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • AIDS Vaccines*
  • Adolescent
  • Adult
  • Female
  • Follow-Up Studies
  • HIV Infections / immunology
  • HIV Infections / prevention & control*
  • HIV Infections / psychology*
  • Health Knowledge, Attitudes, Practice
  • Humans
  • Kenya
  • Longitudinal Studies
  • Male
  • Middle Aged
  • Motivation
  • Patient Selection*
  • Socioeconomic Factors
  • Young Adult


  • AIDS Vaccines