Still no dice for herpes vaccine

An initially promising vaccine against herpes (HSV-1 and HSV-2) has failed in a large clinical trial, the results of which were just published in The New England Journal of Medicine. Researchers, led by a specialist in infectious diseases at St. Louis University in Missouri, are especially disappointed, given that two earlier but smaller trials for this new vaccine had found it effective.

The latest double-blind clinical trial randomly assigned 8,323 women, aged 18 to 30, who had no antibodies to HSV-1 or HSV-2, to receive either the herpes vaccine or a hepatitis A vaccine. While it did provide some protection against HSV-1 (most commonly associated with cold sores), the experimental vaccine did not protect against HSV-2 (the primary cause of genital herpes), and was only 20 percent effective overall at reducing the incidence of genital herpes. Researchers theorize that this rate of protection, which can t compare with the over 70 percent efficacy rate shown in the earlier trials, may be explained by the fact that those initial trial participants had male partners who were already infected with one of the two viruses.

A vaccine against HSV-2 would have been a major advance, says ACSH s Dr. Josh Bloom. In the US, about one person in six is infected with genital herpes. The disease is partially manageable with the antiviral drug valacyclovir, either at the start of an outbreak, or chronically, to minimize the frequency outbreaks and degree of infectivity. There is, however, no cure, and the disease can still be transmitted in the absence of symptoms. This is not a trivial infection.