Experimental Herpes Vaccine
Published on Jan 26, 2012
An experimental vaccine for genital herpes had mixed results in a trial featuring women, according to a recent study.
Genital herpes is a sexually-transmitted disease (STD) caused by one of two types of the herpes simplex virus (HSV). HSV-1 is generally associated with mouth sores, but can also affect the genitals. HSV-2 is usually linked to genital sores and blisters.
There is currently no cure for genital herpes and no approved vaccine to help prevent it.
In the study, American and Canadian researchers found that the vaccine did help prevent some new cases of genital herpes caused by HSV-1. However, it was not effective against genital herpes caused by HSV-2.
Over 8,000 women between the ages of 18 and 30 participated in the study. When the study began, none of the women were infected with either type of HSV.
The women were randomly divided into two groups. One group received three doses of the experimental vaccine. The first dose was given at the start of the study. The second was given one month later and the third was given six months later.
The second group served as the control group and was given a hepatitis A vaccine instead.
The women were followed for 20 months. During this time, they were checked regularly to see if they had developed genital herpes. They were also given blood tests to see if they were infected but not having symptoms.
The researchers found that among the women who had the experimental vaccine, there were 58% fewer cases of genital herpes caused by HSV-1 when compared to the women who got the hepatitis vaccine. However, the vaccine did not prevent cases caused by HSV-2.
“We were surprised by these findings,” said Dr. Robert Belshe, the lead author of the study, in a Saint Louis University press release. “We didn’t expect the herpes vaccine to protect against one type of herpes simplex virus and not another. We also found it surprising that HSV-1 was a more common cause of genital disease than HSV-2.”
Typically, HSV-1 causes fewer cases of genital herpes, but those cases are becoming more common as more couples engage in oral sex.
Both viruses can be transmitted by direct contact with the mouth and/or genitals. The viruses can be spread even if the infected person is not having symptoms. Many people do not know that they are infected.
According to Dr. Belshe, HSV-1 is more vulnerable to antibodies than HSV-2. This might explain why the vaccine antibodies were more successful against HSV-1. However, researchers are still studying the serum of participants to learn more.
The study was published in the January 5, 2012 edition of the New England Journal of Medicine. It was funded by the National Institute of Allergy and Infectious Diseases (part of the National Institutes of Health) and GlaxoSmithKline, the developer of the experimental vaccine.
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