Simplirix, a herpes simplex experimental vaccine did not meet its primary trial endpoint – the prevention of genital herpes disease in women – so GlaxoSmithKline announced today it is not going to pursue any further worldwide development. Although the vaccine was found to be safe, it was not effective, according to the Herpevac Trial for Women, a Phase III trial, carried out with the collaboration with the National Institute of Allergy and Infectious Diseases, USA, part of the NIH (National Institutes of Health).

The trial involved 8,323 women aged between 18 and 30 years at 50 sites across the USA and Canada. They all received the experimental vaccine. At the start of the trial all the women were free of infection by either the herpes simplex 1 virus (HSV-1, the cold sore-causing one) or the HSV-2 (genital herpes one).

A final assessment showed that the vaccine had an acceptable safety profile only, but it was not effective.

Gary Dubin, Vice President and Director, Late Clinical Development at GlaxoSmithKline Biologicals said:

We would like to express our gratitude towards our partner NIAID for their proactive collaboration and substantial contribution in the program and the volunteers for their participation in the study.

In a statement, the National Institute of Allergy and Infectious Diseases said that Simplirix vaccine failed to protect the women significantly from the genital herpes-causing virus.

The National Institutes of Health wrote:

The estimate of vaccine effectiveness was 20 percent, but all estimates have statistical uncertainty, and this effect was not substantially different from zero,”

Genital herpes is a sexually transmitted infection caused by HSV (herpes simplex virus). The virus affects the genitals, cervix, as well as the skin in other parts of the body. There are two types of herpes simplex viruses:

  • HSV-1, or Herpes Type 1
  • HSV-2, or Herpes Type 2

Herpes is a chronic condition. Chronic, in medicine, means long-term. However, many people never have symptoms even though they are carrying the virus. Some individuals with HSV have recurring genital herpes. When a person is initially infected the recurrences, if they do occur, tend to happen more frequently. Eventually the remission periods get longer and longer. Each occurrence tends to become less severe as time goes by.

The herpes simples virus (HSV) is easily human transmissible. It is passed from one person to another by close, direct contact. The most common mode of transmission is through vaginal, anal or oral sex. When somebody becomes infected with HSV, it will generally remain dormant.

Click here to read about herpes in more detail.

Source: GlaxoSmithKline, Medical News Today (archives)

Written by Christian Nordqvist