HPV vaccine has no impact on existing infections

A vaccine developed to prevent infection with human papillomavirus virus (HPV) does not help clear the virus in women who are already infected, according to the results of a community-based study published in the Aug. 15 issue of the Journal of the American Medical Association.

Allan Hildesheim, PhD, of the National Cancer Institute in Rockville, Md., and colleagues tested 2,189 Costa Rican women (aged 18 to 25 years) who were positive for HPV-16 or HPV-18. Subjects were randomly assigned to receive either the bivalent HPV-16/18 vaccine or a control hepatitis A vaccine. Doses were administered at enrollment, 1 month, and 6 months. Specimens were collected for HPV DNA testing at 6 months (before the third dose) and 12 months.

At 6 months, viral clearance rates were 33.4% in the vaccine group versus 31.6% in the control group. At 12 months, clearance rates in the vaccine group were 48.8% and 49.8% in the control group.

Hildesheim A, Herrero R, Wacholder S, et al. Effect of human papillomavirus 16/18 L1 viruslike particle vaccine among young women with preexisting infection. A randomized trial. JAMA. 2007;298:743-753.