New Herpes Vaccine Affects Women Only
Scientists Surprised That Vaccine Immunizes Just 1 Sex
Nov. 20, 2002 -- A vaccine developed to protect against genital herpes is making medical history: It's the first vaccine ever shown to work only in one sex.
In two studies by a multinational research team, the results were virtually identical: The vaccine reduced by three-quarters the rate of genital herpes disease in women with no previous herpes infection, but was virtually useless to men. In the second study, it also proved ineffective in women who had the herpes virus that causes cold sores (HSV-1).
"Yes, we're surprised," says David I. Bernstein, MD, director of the Infectious Disease Division at Cincinnati Children's Hospital Medical Center and an author of the studies. "I don't think anybody expected there would be a sex difference. I know that we certainly didn't."
Still, researchers tell WebMD the vaccine offers great promise in slowing the epidemic spread of genital herpes from the HSV-2 virus, which the CDC estimates now infects one in five Americans older than age 12 and causes blindness and death to thousands of newborns each year.
"As a pediatrician, one of the most exciting aspects of this type of vaccine approach is it is probably the best way to prevent neonatal herpes -- and in the U.S., we're seeing about 3,000 cases a year where the infection is passed from mother to baby," says lead researcher Lawrence R. Stanberry, MD, PhD, director of the Sealy Center for Vaccine Development and chairman of Pediatrics at the University of Texas Medical Branch in Galveston.
"It's clear that the best way to prevent this terrible outcome in infants is to prevent infection in the mother. If approved, this vaccine could be similar to the rubella vaccine -- [used] principally to benefit the baby."
The studies were published in the Nov. 21 issue of TheNew England Journal of Medicine.
Genital herpes typically results from infection by herpes simplex type 2 (HSV-2), causing painful lesions on genitalia and increasing susceptibility to other sexually-transmitted diseases, including AIDS. However, recent studies suggest that genital herpes can also be caused by oral sex with someone infected with the more common HSV-1, which infects about 80% of Americans and causes cold sores or fever blisters on the lips or face.
Both forms of the virus are incurable, and those infected may not even know it. The virus may lie dormant for years or decades, producing little or no symptoms. It is highly contagious when active.
The two studies involved more than 2,700 people in the U.S, Canada, Italy, New Zealand, and Australia between 18 and 45 years old. In both studies, the people had regular sex partners who had a history of genital herpes. Some study participants received three doses of the vaccine and others got a placebo injection -- at the start of the study, one month later, and at six months. They were monitored for 19 months.