A 19-month study, conducted by Lawrence R. Stanberry of the University of Texas Medical Branch and colleagues, involved 978 women and 1,736 men whose partners had genital herpes. The trial determined that GlaxoSmithKline's experimental genital herpes vaccine showed promise in protecting women against the sexually transmitted disease. Participants in the study received either three injections of the vaccine or three injections of a placebo during the first six months of the study. The drug company will conduct a larger study involving women between the ages of 18 years and 30 years to make more specific determinations about the vaccine's prevention success rate. Stanberry, whose findings were published Thursday in the New England Journal of Medicine, believes the vaccine will help prevent neonatal herpes, which infects up to 3,000 newborns per year and is often fatal if not aggressively treated.