PREPARATIONS FOR AIDS VACCINE TRIALS - RETENTION, BEHAVIOR-CHANGE, AND HIV-SEROCONVERSION AMONG INJECTING DRUG-USERS (IDUS) AND SEXUAL PARTNERS OF IDUS

The likelihood that subjects in human immunodeficiency virus (HIV) vac cine efficacy trials will alter their behavioral risks for HIV infecti on over time must be considered in evaluating the feasibility of such trials and in estimating the necessary sample sizes to be enrolled. Po tential subjects for future vaccine efficacy trials include injecting drug users (IDUs) and others who may be difficult to retain in studies and who may alter HIV-risk-related behaviors substantially over time. We have investigated behavior change, retention, and HIV seroconversi on among 577 New York City resident IDUs and sexual partners of IDUs e nlisted between July 1 and December 31, 1992. We attempted to see all subjects every 3 months for interviews, blood donation and HIV testing . We were able to retain 68% of subjects in the study through the thir d scheduled recall at 7.5-10.5 months after enlistment. HIV-seroconver sion through March 1, 1994, was 1.33/100 person-years at risk. There w as a significant inverse relationship between HN seroconversion and re tention at the 9-month recall after adjusting for age, gender, and the amount of locator information provided by subjects at enlistment. Amo ng subjects seen at each of the scheduled visits at 3, 6, and 9 months after enrollment, modest but statistically significant behavior chang es that reduced risk were observed in self-reported drug injection fre quency, heroin injection frequency, sexual contact with IDUs, and shar ing of needles/syringes. The magnitude of these changes in risk, howev er, was small and may be transient. The behavior changes observed to d ate do not appear to be large enough to substantially alter calculatio ns of sample sizes needed in future HIV vaccine efficacy trials.