Experimental Genital Herpes Vaccine Fails Major Clinical Trial

Researchers said on Thursday that an experimental vaccine to protect women from genital herpes disease had failed in a Phase III trial. GlaxoSmithKline, which manufactured the candidate, said it is abandoning its work on the Simplirix vaccine. The Herpevac trial, which began in 2002, enrolled 8,323 women ages 18-30 at 50 sites in the United States and Canada. All were free of herpes simplex virus types 1 and 2 at enrollment. Half the women received the Havrix hepatitis A vaccine (control group), while the others received Simplirix, which contains HSV protein and an adjuvant to boost immune response (intervention group). Volunteers were vaccinated at baseline and months one and six, then followed up for 20 months. The results found the vaccine candidate was ineffective. Its estimated efficacy was 20 percent, a level that is not statistically significant from zero. Researchers are continuing to evaluate the data, but it is not known now why the vaccine failed. Participants who received Simplirix will be offered the opportunity to receive Havrix. The National Institute of Allergy and Infectious Diseases supported the study. For more information, visit www.niaid.nih.gov/news/newsreleases/2010/Pages/Herpevac.aspx and www.niaid.nih.gov/news/QA/Pages/HerpevacQA.aspx.