Herpes vaccine study produces partial victory

Finding a vaccine to stop herpes has been frustrating for researchers. The family of herpes viruses inflict suffering on millions of people. Herpes simplex virus type 1 is generally linked to fever blisters and genital herpes and type 2 causes genital sores.

A study published Wednesday shows progress toward a vaccine but hardly perfection. Researchers evaluated 8,323 women ages 18 to 30 who were not infected with either virus. Almost 3,800 of the study participants received an experimental vaccine known as glycoprotein D. Previous studies suggested the vaccine could be effective against herpes type 2.

But after 20 months of follow-up, the new study found the vaccine was partially effective in preventing herpes type 1 (after two or three doses) and failed to prevent herpes type 2. Overall, the vaccine reduced type 1 infection by about 35% in the vaccinated women.

The disappointing results are puzzling, said the authors, led by Dr. Robert Belshe, director of the Saint Louis University Center for Vaccine Development. It’s not clear why the new study results diverged from the more promising earlier studies. Moreover, researchers can’t explain the difference in vaccine effectiveness between the two herpes strains. “. . .additional progress is needed before a herpes vaccine is likely to be approved for general use,” they wrote.

Once infected, the herpes virus stays in the body. Some infected people never have outbreaks of painful blisters while others have recurring disease. There is no cure, although infected individuals can take antiviral medications to prevent and treat outbreaks. About 25% of U.S. women are infected with herpes, and the virus can be dangerous to infants if transmitted during childbirth.

However, even a partially effective vaccine against type 1 may be of public-health significance. While medical experts used to think of type 1 as strictly causing oral blisters and type 2 as the genital form, increasingly, herpes 1 is responsible for cases of genital herpes.

The study appears in the New England Journal of Medicine.

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