Once-daily suppressive therapy with the antiviral valacyclovir not only reduces the frequency of genital herpes outbreaks, but also significantly reduces shedding of the virus, thereby cutting the risk of transmission to half that associated with taking placebo, according to a recently published study.
Researchers from the Valacyclovir Transmission Study Group studied 1,484 immunocompetent, heterosexual, monogamous couples of which one member was herpes simplex virus type-2 (HSV-2)-seropositive and one was seronegative. The positive partners received either 500 mg oral valacyclovir or placebo once daily for 8 months.
Of the 743 couples with a member taking valacyclovir, 14 of the mates acquired the virus (1.9%) versus 27 of the partners of those receiving placebo (3.6%). In addition, about half those taking valacyclovir versus those taking placebo experienced a genital recurrence during the study (39% vs. 77%, respectively), and the time to recurrence was significantly longer in those taking valacyclovir (0.11 vs. 0.4, respectively).
The investigators caution that since the drug does not block viral transmission in all users, HSV-2-positive individuals should still disclose the virus to susceptible partners and continue to use condoms and other safe sex practices.
Corey L, Wald A, Patel R, et al. Once-daily valacyclovir to reduce the risk of transmission of genital herpes. N Engl J Med. 2004;350:11-20.