Condoms are highly effective at preventing HSV-2 acquisition, especially for women

Effect of condom use on per-act HSV-2 transmission risk in HIV-1, HSV-2-discordant couples.

Magaret AS, Mujugira A, Hughes JP, Lingappa J, Bukusi EA, DeBruyn G, Delany-Moretlwe S, Fife KH, Gray GE, Kapiga S, Karita E, Mugo NR, Rees H, Ronald A, Vwalika B, Were E, Celum C, Wald A, Partners in Prevention HSVHIVTST. Clin Infect Dis. 2015 Nov 17. pii: civ908. [Epub ahead of print]

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 been 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.

Abstract access [1]

Editor’s notes: HSV-2 is extremely prevalent in sub-Saharan Africa, and an important co-factor in HIV transmission. Although condoms are recommended for preventing HSV-2 infection, there have been no previous studies of their effectiveness on a per-sex act basis. This study in HIV and HSV-2 discordant couples participating in an HIV prevention trial examined the risk of HSV-2 transmission for each sex act with and without male condoms. At enrolment, index partners were living with both HIV and HSV-2 infections; susceptible partners were negative for both infections.

The authors found that condoms provided greater protection against HSV-2 acquisition for women than for men, reducing the risk of transmission by 96% from men to women, and by 65% from women to men. However, the overall risk of HSV-2 infection was much higher for women – for each condomless sex act, women were nearly 20 times more likely than men to become infected. As a result, even when using condoms, susceptible women had only a slightly lower risk of infection than men did without condoms. Interestingly, HSV-2 suppressive therapy with acyclovir did not have any effect on HSV-2 transmission, for either sex. Although the authors were not able to confirm that the HSV-2 transmissions occurred within the partnership (e.g. by sequencing the HSV2 DNA), an analysis restricted to couples who never reported sex outside the partnership illustrated very similar results.

The difference in the protection provided by condoms between the sexes may be explained by the fact that, in men, HSV-2 viral shedding is primarily from the penile shaft whereas in women the virus is shed from the wider area of the perineum, and hence condoms are less effective for female-male transmission. These findings indicate that, in individuals who are both HIV and HSV-2 positive, male condoms are extremely effective in preventing male-to-female transmission of HSV-2, and also provide some protection against female-to-male transmission. Although condoms may not provide the same level of protection in populations who are HIV negative, their promotion remains an important public health activity for preventing HSV-2 infection.

Africa [6]
Botswana [7], Kenya [8], Rwanda [9], South Africa [10], Uganda [11], United Republic of Tanzania [12], Zambia [13]
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