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Compendium of Evidence-Based Interventions and
Best Practices for HIV Prevention



Intervention Description

Target Population
HIV-seronegative men who have sex with men (MSM)

Goals of Intervention

  • Prevent the acquisition of new HIV infection
  • Reduce unprotected anal intercourse, serodiscordant unprotected anal intercourse, and serodiscordant unprotected receptive anal intercourse

Brief Description

The EXPLORE intervention consists of 10 core counseling sessions delivered one-on-one to participants. The first 3 sessions are intended to establish rapport between the counselor and the participant, and to provide personalized risk assessments. The remaining 7 sessions cover topics such as sexual communication, knowledge of personal and others’ HIV serostatus when making sexual decisions, and the role of alcohol and drug use in risk behavior. Sessions also address coping with triggers of unsafe sex and skills needed to modify risky behavior. Motivational interviewing is used to help participants make and sustain knowledge, attitude, belief and behavior changes. Maintenance counseling booster sessions are delivered every 3 months after the initial 10 sessions.

Theoretic Basis

  • Information-Motivation-Behavior skill model
  • Motivational enhancement
  • Social Learning Theory

Intervention Duration
Ten 1-hour core counseling sessions delivered within 4 to 6 months, followed by up to 7 maintenance booster sessions delivered every 3 months up to 45 months. Participants also received HIV testing and counseling every 6 months.

Intervention Settings
HIV Prevention Trials Network sites, in the field or by telephone

Counselors who completed 40 hours of training

Delivery Methods

  • Counseling
  • Goal setting
  • Motivational interviewing
  • Risk reduction supplies (condoms)

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Intervention Package Information

The intervention manual is available online. Contact Dr. Beryl A. Koblin, Laboratory of Infectious Disease Prevention, New York Blood Center, 310 East 67th St., New York, NY 10021, e-mail:, for details on intervention materials. Based on the non-significant effect of the intervention on the primary outcome of the study, HIV incidence, The EXPLORE Study Team does not recommend use of the intervention in its present form.

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Evaluation Study and Results

The original evaluation study was conducted in 6 cities (Boston, Chicago, Denver, New York, San Francisco, and Seattle) between 1999 and 2003. Of the 4,295 men who participated in the study, 64% had a college degree.

Key Intervention Effects

  • Decreased unprotected anal sex
  • Decreased serodiscordant unprotected anal sex
  • Decreased Serodiscordant unprotected receptive anal sex

Study Sample

  • 72% White, 15% Hispanic, 7% African American, 6% Other
  • 100% Male
  • Mean age of 34 years

Recruitment Settings
Active recruitment included outreach in streets, at dance clubs, bars, bathhouses, sex clubs, health clubs, and video stores. Other venues included Internet sites, community forums, community agencies, and referrals from study participants and clinics.

Eligibility Criteria
Men were eligible if they were HIV-seronegative, were aged 16 years or older, and reported having engaged in anal sex with one or more men in the prior year. Men were excluded if they were in a mutually monogamous relationship lasting 2 years or longer with a male partner known to be HIV-seronegative.

Assignment Method
Men were randomly assigned to either the EXPLORE intervention group (n = 2,144) or standard comparison group (n = 2,151).

Comparison Group
The standard comparison group included twice yearly risk reduction counseling based on CDC’s Project Respect model and HIV counseling and testing at each follow-up assessment.

Relevant Outcomes Measured and Follow-up Time

  • Incident HIV using ELISA at every 6-month follow-up visit up to 45 months
  • Sexual risk behaviors (including any unprotected anal sex, serodiscordant unprotected anal sex, and serodiscordant receptive unprotected anal sex) were measured at every 6-month follow-up visit up to 45 months
  • Each follow-up was only 3 months after the previous booster session for the intervention group

 Participant Retention

  • EXPLORE Intervention:
    85% retained at 12 months [Range 84% to 86% for all follow-ups]
  • Standard Comparison:
    90% retained at 12 months [Range 87% to 93% for all follow-ups]

Significant Findings
Men in the intervention group were significantly less likely to report any unprotected anal sex, serodiscordant unprotected anal sex, and serodiscordant receptive unprotected anal sex at the 12- and 18-month follow-ups as compared to men receiving the standard comparison intervention (p's < .001).


  • A modest 18% reduction in HIV incidence, the primary outcome, was observed in the intervention relative to control arm; however, this did not achieve statistical significance.
  • Few significant effects were reported at follow-ups longer than 18 months.

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References and Contact Information

  • Chesney, M. A., Koblin, B. A., Barresi, P. J., et al. (2003). An individually tailored intervention for HIV prevention: Baseline data from the EXPLORE study. American Journal of Public Health, 93, 933–938.
  • Koblin, B. A., Chesney, M. A., Husnick, M. J., et al. (2003). High-risk behaviors among men who have sex with men in 6 US cities: Baseline data from the EXPLORE study. American Journal of Public Health, 93, 926–932.
  • The EXPLORE Study Team (2004). Effects of a behavioural intervention to reduce acquisition of HIV infection among men who have sex with men: The EXPLORE Randomised Controlled Study. Lancet, 364, 41–50. 

Researcher: Dr. Beryl A. Koblin
Laboratory of Infectious Disease Prevention
New York Blood Center
310 East 67th St.
New York, NY 10021

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