Risk behaviours and comprehension among intravenous drug users volunteered for HIV vaccine trial

J Med Assoc Thai. 1997 Jan;80(1):47-50.


Out of 91 volunteers enrolled for the HIV vaccine trial, only 33 volunteers were eligible for vaccination. Of 33 volunteers recruited, 59 per cent of them had incomes of more than 5,000 Baht/ month. The median duration of drug addicts was 15 years (range 1-26 years) and 42 per cent never used condoms during sexual intercourse. As far as consent comprehension was concerned, all of them understood.

PIP: With HIV seroprevalence rates of 35-40%, Thai intravenous drug users are an obvious target group for anti-HIV vaccine trials. The Ministry of Public Health of Thailand recently approved clinical trials of the Genentech MN rgp 120/HIV-1 candidate vaccine among recovering intravenous drug users enrolled in a methadone treatment center in Bangkok. To evaluate safety and immunogenicity factors and assemble a relatively low-risk group, 91 potential volunteers from this center were screened (history, physical examination, and blood and urine analysis). Only 33 passed all of the screening procedures; the major causes of ineligibility were HIV seropositivity (14 cases) and impaired liver function test (10 cases). The 33 eligibles had a median duration of drug addiction of 15 years. The majority had a secondary education or above and a monthly income exceeding 5000 Baht (US$200). Never-use of condoms was acknowledged by 14 of the eligible volunteers, but all 33 denied relationships with commercial sex workers. Among those selected for the trial, 23 believed a successful vaccine against AIDS is likely and 30 thought the vaccine they received was effective; however, 12 were concerned the vaccine would enhance disease progression. After 12 months of counseling and participation in the vaccine trial, nine volunteers were drug and methadone-free. Overall, these findings indicate that intravenous drug users can successfully participate in vaccine trials if there is adequate pre-screening.

MeSH terms

  • AIDS Vaccines*
  • Clinical Trials as Topic
  • HIV Infections / prevention & control*
  • Health Knowledge, Attitudes, Practice
  • Humans
  • Informed Consent*
  • Risk-Taking
  • Substance Abuse, Intravenous*
  • Volunteers*


  • AIDS Vaccines