Introduction
An estimated one in four women in the United States has genital herpes, making it among the most common infectious diseases. There is no medication that eliminates herpes infection, and no vaccine to prevent it. That is why the National Institute of Allergy and Infectious Diseases and GlaxoSmithKline are co-sponsoring the Herpevac Trial for Women, a clinical study investigating a promising vaccine to protect women against genital herpes.
The trial is being conducted at more than 40 sites in the United States and Canada. Approximately 7,550 women were enrolled and randomly assigned to receive either the candidate herpes vaccine or an investigational hepatitis A vaccine. Participants received 3 doses of either vaccine within the first 6 months of the trial and were followed for a total of 20 months through periodic clinic visits and contacts.
The vaccine formulation used in the trial contains no live or infectious virus. Instead, it uses only a specific fragment of a herpes virus protein that stimulates immune response.
The Herpevac Trial for Women is fully enrolled and screening is now closed.
Promising Early Clinical Trials
In earlier studies, the herpes vaccine was shown to decrease the risk of developing symptomatic herpes simplex virus (HSV) infection in women who were not previously infected with herpes simplex. For these women, the risk of contracting genital herpes and developing symptoms was reduced by about 75%. The risk of developing antibodies to herpes, which is used as an indicator that a person has been infected, was reduced by about 40%. Unfortunately, women who were already infected with HSV type 1 (HSV-1), the usual cause of cold sores, did not benefit from the herpes vaccine in these earlier studies, and the vaccine was not effective in men. (Results were published in the New England Journal of Medicine (non-government) in November 2002.)
Vaccine Safety Information
The vaccines used in the Herpevac Trial for Women have been studied previously in thousands of individuals. Both vaccines have met safety requirements needed for larger clinical trials such as this one, which focus on further evaluating the vaccine's effectiveness in preventing disease.
The investigational herpes vaccine was studied in approximately 7,400 volunteers in previous Phase III trials and was generally well-tolerated. Non-serious side effects at the site of the injection associated with the herpes vaccine included soreness, redness, or swelling, usually lasting between 1-3 days. Other side effects noted were tiredness (fatigue), headache, general feeling of not feeling well, and less often, mild fever. These symptoms usually did not last more than 24 hours, nor did they prevent the volunteers' normal daily activities. There were only 9 reports of side effects that were considered by the investigators to be serious and related -- or possibly related -- to the herpes vaccine.
The investigational hepatitis A vaccine being used in this study has actually been given to millions of people. Based on a licensed hepatitis A vaccine, the vaccine utilized in this study is considered investigational because it will be given at a lower dose and in a smaller volume compared to the approved hepatitis A vaccine. The most common side effects associated with the vaccine included injection site soreness, redness, swelling or hardening; headache; fatigue; fever; not feeling well; loss of appetite; and nausea.
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