New Herpes Vaccine Affects Women Only
Scientists Surprised That Vaccine Immunizes Just 1 Sex
In the first study, the 270 women and 580 men were all free of either HSV-1 or HSV-2. Compared with women getting a placebo injection, the vaccine reduced genital herpes disease in women by 73%. "But low and behold, it did pretty much nothing in men," Bernstein tells WebMD. "So we did a second study."
The team then tracked more than 700 women and 1,100 men, some of who had HSV-1 but not HSV-2 . The vaccine proved 74% effective -- but only in a subgroup of women without HSV-1. Neither the women with the "cold sore" virus nor the men were protected by the vaccine.
Though the sex disparity isn't clear, researchers say it may have to do with how HSV enters the body. In women, the virus enters through the vaginal mucous membrane -- which already is bathed in antibodies and disease-fighting T cells. "So more vaccine-induced antibodies flood to the mucous membranes for more coating," says Bernstein. "In men, the virus usually enters through cracks in their skin, which aren't bathed in antibodies."
And the HSV-1 connection? "It's not so much that the vaccine didn't work in those who have HSV-1 already," he tells WebMD. "Rather, HSV-1 itself may already provide a level of protection against the disease that is similar to that of the vaccine."
The vaccine, developed by GlaxoSmithKline, which paid for the studies, is made from a protein in the genital herpes virus. A third study, also sponsored by the drug manufacturer and now in conjunction with the National Institutes of Health, will begin this month to further test the vaccine in nearly 8,000 women between ages 18 and 30. GlaxoSmithKline is a WebMD sponsor.
If that study produces similar results and the FDA approves the vaccine, it could be on the market in about five years -- available only for women.
"In order to be maximally effective, you need to immunize women before they become sexually experienced, so if approved, our goal is to target young adolescent girls -- probably between ages 10 and 13," Stanberry tells WebMD. "In the same issue of New England Journal as our studies is some very promising research about a vaccine for the human papillomavirus, the leading cause of cervical cancer. I believe that we may soon see a whole series of reproductive health vaccines for young women to help stop these sexually transmitted diseases."