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Title

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

Authors

BA Koblin, KH Mayer, E. Noonan, et al.

Network Affiliation

Other

Organization

 

Journal Name

JAIDS

Publication Date

8/1/2012

PubMed Search

http://www.ncbi.nlm.nih.gov/pubmed?term=Sexual%20Risk%20Behaviors%2C%20Circumcision%20Status%2C%20and%20Preexisting%20Immunity%20to%20Adenovirus%20Type%205%20Among%20Men%20Who%20Have%20Sex%20With%20Men%20Participating%20in%20a%20Randomized%20HIV-1%20Vacci

Link to full-text

 

PMID

 

Abstract

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 .

Keywords

 

Topic

Behavior; MSM

Attachments

Created at 7/20/2012 11:31 AM by Davis, Gregory P
Last modified at 7/20/2012 11:31 AM by Davis, Gregory P