Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Clinical Trial
. 2012 Aug 1;60(4):405-13.
doi: 10.1097/QAI.0b013e31825325aa.

Sexual risk behaviors, circumcision status, and preexisting immunity to adenovirus type 5 among men who have sex with men participating in a randomized HIV-1 vaccine efficacy trial: step study

Beryl A Koblin  1 , Kenneth H Mayer, Elizabeth Noonan, Ching-Yun Wang, Michael Marmor, Jorge Sanchez, Stephen J Brown, Michael N Robertson, Susan P Buchbinder
Affiliations
Clinical Trial

Sexual risk behaviors, circumcision status, and preexisting immunity to adenovirus type 5 among men who have sex with men participating in a randomized HIV-1 vaccine efficacy trial: step study

Beryl A Koblin et al. J Acquir Immune Defic Syndr. .

Abstract

Background: The Step Study found that men who had sex with men (MSM) who received an adenovirus type 5 (Ad5) vector-based vaccine and were uncircumcised or had prior Ad5 immunity, had a higher HIV incidence than MSM who received placebo. We investigated whether differences in HIV exposure, measured by reported sexual risk behaviors, may explain the increased risk.

Methods: Among 1764 MSM in the trial, 726 were uncircumcised, 994 had prior Ad5 immunity, and 563 were both uncircumcised and had prior Ad5 immunity. Analyses compared sexual risk behaviors and perceived treatment assignment among vaccine and placebo recipients, determined risk factors for HIV acquisition, and examined the role of insertive anal intercourse in HIV risk among uncircumcised men.

Results: Few sexual risk behaviors were significantly higher in vaccine versus placebo recipients at baseline or during follow-up. Among uncircumcised men, vaccine recipients at baseline were more likely to report unprotected insertive anal intercourse with HIV-negative partners (24.9% vs. 18.1%; P = 0.03). Among uncircumcised men who had prior Ad5 immunity, vaccine recipients were more likely to report unprotected insertive anal intercourse with partners of unknown HIV status (46.0% vs. 37.8%; P = 0.05). Vaccine recipients remained at higher risk of HIV infection compared with placebo recipients (hazard ratio = 2.8; 95% confidence interval, 1.2-6.8) controlling for potential confounders.

Conclusions: These analyses do not support a behavioral explanation for the increased HIV infection rates observed among uncircumcised men in the Step Study. Identifying biologic mechanisms to explain the increased risk is a priority .

PubMed Disclaimer

Figures

Figure 1A
Figure 1A
Number of male partners among uncircumcised men, Step Study
Figure 1B
Figure 1B
Number of male partners among men with prior Ad5 immunity, Step Study
Figure 1C
Figure 1C
Number of male partners among uncircumcised men with prior Ad5 immunity, Step Study
See this image and copyright information in PMC

References

    1. Hall HI, Song R, Rhodes P, et al. Estimation of HIV incidence in the United States. JAMA. 2008;300:520–529. - PMC - PubMed
    1. Sanders EJ, Graham SM, Okuku HS, et al. HIV-1 infection in high risk men who have sex with men in Mombasa, Kenya. AIDS. 2007;21:2513–2520. - PubMed
    1. van GF, de Lind van Wijngaarden JW. A review of the epidemiology of HIV infection and prevention responses among MSM in Asia. AIDS. 2010;24(Suppl 3):S30–S40. - PubMed
    1. Abdool KQ, bdool Karim SS, Frohlich JA, et al. Effectiveness and safety of tenofovir gel, an antiretroviral microbicide, for the prevention of HIV infection in women. Science. 2010;329:1168–1174. - PMC - PubMed
    1. Grant RM, Lama JR, Anderson PL, et al. Preexposure Chemoprophylaxis for HIV Prevention in Men Who Have Sex with Men. N Engl J Med. 2010 - PMC - PubMed

Publication types