Effect of Condom Use on Per-act HSV-2 Transmission Risk in HIV-1, HSV-2-discordant Couples

BACKGROUND:

The efficacy of condoms for protection against transmission of herpes simplex virus type 2 (HSV-2) has been examined in a variety of populations with different effect measures. Often the efficacy has been assessed as change in hazard of transmission with consistent vs inconsistent use, independent of the number of acts. Condom efficacy has not previously measured on a per-act basis.

METHODS:

We examined the per-act HSV-2 transmission rates with and without condom use among 911 African HSV-2 and human immunodeficiency virus type 1 (HIV-1) serodiscordant couples followed for an average of 18 months in an HIV prevention study. Infectivity models were used to associate the log₁₀ probability of HSV-2 transmission over monthly risk periods with reported numbers of protected and unprotected sex acts. Condom efficacy was computed as the proportionate reduction in transmission risk for protected relative to unprotected sex acts.

RESULTS:

Transmission of HSV-2 occurred in 68 couples, including 17 with susceptible women and 51 with susceptible men. The highest rate of transmission was from men to women: 28.5 transmissions per 1000 unprotected sex acts. We found that condoms were differentially protective against HSV-2 transmission by sex; condom use reduced per-act risk of transmission from men to women by 96% (P < .001) and marginally from women to men by 65% (P = .060).

CONCLUSIONS:

Condoms are recommended as an effective preventive method for heterosexual transmission of HSV-2.

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By:  Magaret AS1, Mujugira A2, Hughes JP3, Lingappa J4, Bukusi EA5, DeBruyn G6, Delany-Moretlwe S7, Fife KH8, Gray GE9, Kapiga S10, Karita E11, Mugo NR5,Rees H7, Ronald A12, Vwalika B13, Were E14, Celum C15, Wald A16; Partners in Prevention HSV/HIV Transmission Study Team.

• 1Department of Laboratory Medicine Department of Biostatistics Department of Global Health.
• 2Department of Global Health Department of Epidemiology, University of Washington.
• 3Department of Biostatistics Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center.
• 4Department of Global Health Department of Pediatrics Department of Medicine, University of Washington, Seattle.
• 5Center for Microbiology Research, Kenya Medical Research Institute (KEMRI), Nairobi.
• 6Sanofi Pasteur, Swiftwater, Pennsylvania.
• 7Wits Reproductive Health and HIV Institute, University of the Witwatersrand, Johannesburg, South Africa.
• 8Department of Medicine, Indiana University, Indianapolis.
• 9Perinatal HIV Research Unit, University of the Witwatersrand, Johannesburg, South Africa.
• 10London School of Hygiene and Tropical Medicine, United Kingdom.
• 11Rwanda-Zambia HIV Research Group, Kigali, Rwanda, Lusaka, Zambia.
• 12Department of Medicine, University of Manitoba, Winnipeg, Canada Infectious Disease Institute, Makerere University, Kampala, Uganda.
• 13Rwanda-Zambia HIV Research Group, Kigali, Rwanda, Lusaka, Zambia Department of Obstetrics and Gynaecology, University of Zambia, School of Medicine, Lusaka.
• 14Department of Reproductive Health, Moi University, Eldoret, Kenya.
• 15Department of Global Health Department of Epidemiology, University of Washington, Department of Medicine, University of Washington, Seattle.
• 16Department of Laboratory Medicine Department of Epidemiology, University of Washington, Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center Department of Medicine, University of Washington, Seattle. 

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