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A quadrivalent human papillomavirus (HPV) vaccine was licensed in 2006, and the CDC published official recommendations in 2007. The CDC guidelines warn that girls and women should be informed that the vaccine is not a substitute for routine cervical cancer screening. To examine whether the HPV vaccine has therapeutic benefit in infected individuals, investigators in Costa Rica randomized more than 2000 HPV DNA-positive women (age range, 18–25) to receive three doses of either an HPV vaccine against the oncogenic types 16 and 18 or a control hepatitis A vaccine (HAV) at 0, 1, and 6 months.
Patients were assessed by HPV DNA testing at enrollment and at 6 and 12 months. About 19% of the women were positive for HPV 16, and 7% were positive for HPV 18. Clearance rates for HPV-16/18 infection were similar in the HPV-vaccine and HAV groups at 6 months (33% and 32%, respectively) and at 12 months (49% and 50%, respectively).
Hildesheim A et al. Effect of human papillomavirus 16/18 L1 viruslike particle vaccine among young women with preexisting infection. JAMA 2007 Aug 15; 298:743-53.
Comment
These data confirm that immunization with HPV vaccine has no therapeutic effect on preexisting infections. We can provide true prophylaxis against HPV only if we vaccinate girls and women before they initiate sexual activity. Although the lay press may tout HPV vaccine as the “cancer vaccine,” young women still need routine Pap testing and standard gynecologic follow-up for existing lesions.