Revisiting the Valacyclovir Transmission Study
Do more frequent recurrences of genital herpes translate into a greater risk of transmission to uninfected partners? That’s the question researchers were attempting to answer when they revisited the results of the landmark 2004 valacyclovir transmission study. This large scale clinical trial demonstrated that suppressive treatment with 500mg of valacyclovir once daily reduced transmission of genital HSV-2. After reexamining the data from the 1484 HSV-2 serodiscordant* couples in the trial, researchers found no correlation between the frequency of recurrences and the risk of transmission to an uninfected partner. In other words, more recurrences did not equal a greater transmission risk.
Researchers evaluated individuals who acquired HSV-2 during the eight-month study and analyzed recurrences in their respective partners. When reviewing reported recurrences in the year prior to the study, they found no significant differences in the time to new infection for those whose partners had five or more recurrences in the year prior to enrolling in the study and those whose partners had fewer than five recurrences. Taking into account recurrences during the course of the study, the overall transmission rate did not differ between those HSV-2 positive partners who had the highest rates of recurrence and those who had the lowest rates. More than one-third of those who infected their partner had no recurrences during the study period.
Results of this analysis, published earlier this year in Sexually Transmitted Diseases, support current knowledge about transmission risk: individuals with and without symptoms shed virus genitally; those with a history of symptoms are not more likely to have subclinical reactivation; and most cases of transmission appear to occur during periods when no clinical symptoms are present. As the study authors conclude, “Clinical assessment of HSV-2 disease severity as defined by number of recurrences appears to be a poor predictor of the risk of transmission to sexual partners. Though persons with frequent recurrences are most likely to benefit clinically from suppressive antiviral therapy, they do not appear to represent any higher risk of transmission than those with less frequent recurrences . . . When discussing prevention of transmission with HSV-2-serodiscordant couples, health care providers should consider suppressive antiviral medication in patients with a clinical history of genital HSV-2 infection regardless of disease severity in the infected partner.”
*Serodiscordant indicates a difference in serological status. So in an HSV-2 serodiscordant couple, one individual would be HSV-2 positive and one individual would be HSV-2 negative.