Willingness to participate in AIDS vaccine trials among high-risk populations in northern Thailand

AIDS. 1995 Sep;9(9):1079-83. doi: 10.1097/00002030-199509000-00015.


Objectives: To determine the anticipated participation in a prophylactic AIDS vaccine trial and to identify perceived benefits and barriers to enrollment of HIV-seronegative volunteers at risk of HIV infection in northern Thailand.

Design: A cross-sectional survey.

Methods: Subjects interviewed in a cross-sectional survey included female commercial sex workers (n = 215), men attending sexually transmitted disease clinics (n = 219), conscripts in the Royal Thai Army (n = 1453), and men discharged from the army (n = 293) who had returned to civilian life. We determined AIDS vaccine knowledge and attitudes, perceived vulnerability to HIV infection, barriers and incentives to participate in a future vaccine trial and agreement to participate in a randomized trial.

Results: Awareness of vaccines (88-97%) and AIDS vaccine development efforts (62-77%) were common and viewed to be a complement to behavior change (74-94%). Approximately 25% of subjects would definitely join a trial if asked, and an additional 38% would accept an AIDS vaccine if they were convinced it would be safe and effective. Important barriers to participation included concerns with discrimination (16-45%), short- (37-60%) and long-term (30-55%) vaccine side-effects, fear of disability and death (36-58%), and beliefs that partners would refuse to have sex (24-49%) after immunization. The principal inducement to join a trial was health insurance (62%).

Conclusion: Potential HIV vaccine trial participants have several fears of joining a vaccine study at this time. Information derived from Phase I/II trials is needed to address these concerns if enrollment in efficacy trials is to be successful in the near future.

PIP: Thailand has been designated a site for preventive human immunodeficiency virus (HIV) vaccine trials, and Phase I and II trials are currently underway. To assess the feasibility of large-scale Phase III trials involving high-risk individuals, questionnaires were administered to four cohorts of potential participants from North Thailand: 215 female commercial sex workers recruited from sexually transmitted disease (STD) clinics, 219 male STD clients from the same area, 1453 men conscripted into the Royal Thai Army in 1993, and 293 men discharged from the Army in 1993. Approximately 25% of members of each cohort indicated they would definitely join a prophylactic acquired immunodeficiency syndrome (AIDS) trial. The major barriers to participation were concerns about vaccine safety (61% of military cohorts and 32% of civilians) and fear of acquiring AIDS through vaccination (21%). Also expressed were concerns about social discrimination, immediate side effects, and rejection by sexual partner. Two-thirds of respondents indicated that provision of a five-year family health insurance plan would induce them to participate in a vaccine trial, while another 25% did not require any incentive. Overall, these findings indicate that steps must be taken to alleviate fears and misconceptions associated with HIV vaccines before Phase III is initiated.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • AIDS Vaccines / administration & dosage*
  • AIDS Vaccines / adverse effects
  • AIDS Vaccines / immunology
  • Acquired Immunodeficiency Syndrome / immunology
  • Acquired Immunodeficiency Syndrome / prevention & control*
  • Acquired Immunodeficiency Syndrome / transmission
  • Adult
  • Clinical Trials as Topic*
  • Cohort Studies
  • Cross-Sectional Studies
  • Female
  • Health Knowledge, Attitudes, Practice
  • Humans
  • Male
  • Motivation
  • Patient Acceptance of Health Care*
  • Risk Factors
  • Sex Work


  • AIDS Vaccines