Valtrex reduces transmission of genital herpes

(29 Oct 2002)

It has long been known that once daily therapy with the leading antivirals reduces aymptomatic viral shedding in those with genital herpes as well as reducing the number of herpes outbreaks. Questions have remained, about whether this antiviral activity translates into a reduced risk of transmission to uninfected partners of those who have genital herpes.

Now, after four years of study, researchers have found that once daily use of the antiviral drug valaciclovir (Valtrex) results in what some experts believe is a significant reduction in the risk of transmission. Results of the study presented in late September at the 42nd ICAAC in San Diego, showed that suppressive Valtrex therapy reduced the overall acquisition of the virus by 50% by uninfected partners in discordant couples.

The study compares valaciclovir tablets against placebo in a total of 1,484 couples. One partner had genital herpes (source partner) while the other (susceptible partner) did not. The source partner, with a history of less than ten episodes per year, was randomised in a 1:1 ratio to receive valaciclovir tablets 500mg once daily during the eight-month study period. The susceptible partner was monitored for signs of the virus, both physically and in the blood, and asked to visit the clinic at the first sign of an outbreak. All couples were offered condoms and counselled on safer sexual behaviour at all study visits.

"This is the first time an anti-viral has been shown to reduce sexual transmission of a sexually transmitted disease and provides another groundbreaking concept in antiviral chemotherapy for this agent," said Larry Corey, M.D., lead study author and professor, Laboratory Medicine and Medicine, University of Washington and head of the Program in Infectious Diseases, Fred Hutchinson Cancer Research Center. "In this study, Valxrex, along with condom use and counselling, reduced the rate of transmission significantly in the population studied. While the effect on reducing transmission was not complete, the use of suppressive therapy provides health care providers and patients with genital herpes an important new tool for managing this increasingly prevalent viral sexually transmitted infection."

Claire Hurst, President of the International Herpes Alliance and Project Co-ordinator for the New Zealand Herpes Foundation, commented "The IHA welcomes this new research and looks forward to working with the medical profession in interpreting this new information to help those affected with genital herpes."

The study was supported by educatioin grant from GlaxoSmithKline, makers of Valtrex.