An update on human immunodeficiency virus vaccine preparedness studies.

Human immunodeficiency virus (HIV) vaccine preparedness studies (VPSs) have taken place in both the Organisation for Economic Co-operation and Development (OECD) countries and the non-OECD countries. HIV VPSs are conducted to assess the feasibility of phase 3 HIV vaccine trials. This descriptive review is an update of HIV VPSs in the non-OECD countries, and examines the willingness to participate (WTP) in hypothetical HIV vaccine trials, as well as retention. Few VPSs have been published in the OECD countries since the discontinuation of the STEP/Phambili HIV vaccine trials. Barriers to participation in the non-OECD countries after the STEP/Phambili studies include safety issues and side effects, vaccine-induced seropositivity (VISP) and mistrust among key informants (KIs). HIV VPSs indicate that HIV vaccine trials are still feasible in the non-OECD countries, but barriers must be overcome to improve feasibility. Hypothetical WTP in a VPS may not translate into actual WTP in an HIV vaccine trial.