Q&A

Vaccine prevents genital herpes in subgroup of women

J Fam Pract. 2003 February;52(2):94-117
By
Charles Cole, MD
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  • BACKGROUND: Can a vaccine prevent genital herpes? HSV infection occurs worldwide and is epidemic in some populations, despite the availability of antiviral agents and condoms. Genital HSV infection may be asymptomatic or severe with painful skin lesions and complications. Infection can also cause significant psychological illness.
  • POPULATION STUDIED: Subjects had regular sexual partners with genital herpes. Study 1 subjects (N=847) were seronegative for HSV-1 and HSV-2 at baseline. Study 2 subjects (N=1867) were of any HSV status. Treatment and control groups did not differ significantly from one another. Most patients were white and heterosexual with a mean age of 30 to 34 years. Just over a third of study participants were women. About 10% of the participants did not complete the 3-dose series.
  • STUDY DESIGN AND VALIDITY: Two double-blinded, randomized trials were performed using an HSV type 2 glycoprotein-Dsubunit vaccine in subjects whose sexual partners had genital herpes. Participants were randomized to receive the vaccine or placebo at 0, 1, and 6 months.
  • OUTCOMES MEASURED: The initial primary outcome for both studies was development of genital herpes in all subjects. After Study 1 results were analyzed but before Study 2 results were known, the primary outcome for Study 2 was changed to the development of genital herpes in HSV-2 seronegative females.
  • RESULTS: Vaccine efficacy was defined as the reduction in the rate of genital herpes in immunized subjects compared with nonimmunized subjects. Study 1 showed no efficacy in preventing HSV infection in subjects who were HSV-1 and HSV-2 seronegative (efficacy=38%; 95% confidence interval [CI], –18 to 68).
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PRACTICE RECOMMENDATIONS

The herpes simplex virus (HSV) type-2 vaccine studied here prevented genital herpes only in women who were seronegative for HSV-1 and HSV-2 at baseline. Ten of these women would need to be vaccinated to prevent 1 case of genital herpes. The vaccine did not prevent infection with HSV-2 in these women. It did not prevent genital herpes in women with other HSV serologic status or in men.

The usefulness of this vaccine is limited by the small subgroup in which it is efficacious. Determining which women fall into this subgroup could prove costly. It is possible that asymptomatic infected persons may spread HSV more readily. Emphasis on the use of condoms and antiviral agents should still be the first line in preventing the spread of genital herpes.

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