An experimental HSV vaccine was not effective in preventing genital HSV-2 infections or disease in women, according to data published in the New England Journal of Medicine.

As with many diseases, the quest for an effective vaccine is the holy grail of HSV research. Results from prior HSV vaccines trials teased with promise: while ineffective in men, in early studies the vaccine prevented genital herpes in more than 70% of women who were free of both HSV-1 and HSV-2 at study entry. Results from expanded research with the vaccine have been disappointing, however.

The most recent data comes from a clinical trial done with over 8,300 women who were seronegative for both HSV-1 and HSV-2 antibodies. The subjects were randomized and received a vaccine for either HSV or hepatitis A. The results in the HSV group were mixed: while the vaccine was 58% effective in preventing genital HSV-1 disease (symptoms, like sores, associated with an outbreak), it was ineffective against disease related to HSV-2 (overall efficacy against any genital HSV disease was 20%). The HSV vaccine was 35% effective in blocking genital HSV-1 infections, with no efficacy observed against genital HSV-2 infection. Infection with HSV occurs when someone simply contracts the virus, whether or not they notice any outbreaks. Because of these results, further development of this vaccine is not going to be pursued.

HSV infections are common, with the majority of adults in the U.S. believed to have HSV-1 (often in the form of oral herpes that causes cold sores). According to the Centers for Disease Control and Prevention (CDC), approximately 17% of adults in the U.S. have HSV-2, most often experienced as a genital infection.

Reference
Belshe R, Leone P, Bernstein D,Wald A, Levin M, Stapleton J, Gorfinkel I, Morrow R, Ewell M, Stokes-Riner A, Dubin G, Heineman T, Schulte J, Deal C. for the Herpevac Trial for Women. Efficacy Results of a Trial of a Herpes Simplex Vaccine. N Engl J Med, 2012. 366:34-43January 5, 2012.