Vaccine prevents spread of herpes among women

Researchers at the pharmaceutical company GlaxoSmithKline reported Thursday that they've produced an effective vaccine for genital herpes for the first time, offering hope that the spread of the incurable, sexually transmitted disease can be minimized. But the vaccine has been shown to be effective only for women, and researchers are still unclear why it doesn't work for men. Glaxo said the results of the clinical study were so promising that the company is launching new Phase III trials that will involve 7,550 women, ages 18 to 30, around the country. If data from that trial prove promising, the company could have the vaccine submitted for regulatory approval and available on the U.S. market in about five years.

Tests on 978 women showed that the experimental vaccine prevented herpes infection in 74% of the study subjects exposed for the first time to herpes simplex virus type 2, the virus that causes the disease. None of the 1,736 men studied received any protection from the vaccine. As many as 45 million Americans carry the virus, most of whom never experience the painful itching and sores associated with the disease. Because symptoms aren't usually present, infected people are less likely to take precautions to keep from transmitting it to their sex partners. Gay men and lesbians can transmit the virus to their sex partners through sexual contact, and condoms and dental dams are not 100% effective in preventing its transmission. Herpes also has been shown to help facilitate HIV infection.

Researchers caution that the vaccine appears to work only for women and can be less effective for women infected with a similar virus, herpes simplex type 1, which causes cold sores and fever blisters. That notwithstanding, the compound still could be a powerful weapon in slowing the rate of herpes infections among sexually active Americans.