Herpes Simplex Virus type 2 Vaccine fails in stage three trials

The search for a vaccine to prevent Herpes Simplex type 2 infection (genital herpes) has been sought after for decades.  The need for an HSV-2 vaccine has recently been highlighted by the observation that people that have genital herpes have a greater increase of risk of getting HIV.  Unfortunately, making an HSV vaccine has proven quite elusive.  Some glimmer of hope, however, had emerged from a subunit vaccine produced by GlaskoSmithKlein (GSK).  In two independent stage II trials, the vaccine prevented HSV transmission in 70% of HSV-1 seronegative women (aka, women that had not been exposed to the closely related virus most often associated with cold sores), encouraging GSK to move to a larger stage three trial.  After 8 years of study, the results of that trail were released on Friday and, sad to say, the 70%  reduction in transmission observed in the stage II trial did not hold up.  In fact, the vaccine only reduced HSV-2 transmission by 20% which was not statistically different than the control group.  It is unclear what steps GSK will take from here but if they do continue with an HSV vaccine program, it probably will be starting from scratch.