Toronto — Researchers have made the first vaccine that protects against genital herpes, but there is a big catch: It works only in women and only if they have never had cold sores.
The findings, reported Sunday, are a surprise. Until now, no vaccine has ever been shown to work in one sex but not the other. Experts say this could present unexpected trouble for creating other vaccines for sexually transmitted diseases, such as AIDS.
The results were not the clear home run that the vaccine's developer, SmithKline Beecham, had hoped when it began designing the latest studies a decade ago. Further testing will almost certainly be required for the drug to be approved, assuming that the company keeps working on the product.
Nevertheless, doctors say a vaccine that offers even partial protection against a chronic disease is noteworthy. The only other sexually transmitted disease that can be stopped with a vaccine is hepatitis B.
"I would say the chances are good but not at all certain" that the herpes vaccine will eventually be approved for routine use, said Dr. Spotswood Spruance of the University of Utah.
He predicted the vaccine would be given to adolescent girls. Widespread use of the vaccine this way would probably reduce genital herpes for both sexes, since it would lower the chance of men coming in contact with infected females.
Genital herpes and cold sores result from closely related bugs. Herpes simplex virus type 1, or HSV-1, causes fever blisters on the mouth, while HSV-2 triggers sores on the genitals. Once acquired, both infections last a lifetime.