Women without evidence of prior HPV 16 or 18 exposure—defined as the absence of HPV 16 or 18 antibodies in blood, and no DNA evidence of cervical HPV 16 or 18 infection at time of first vaccination—experienced the greatest protection, with an efficacy of approximately 84 percent at any site, Dr. Beachler reported.
The vaccine efficacy was lower but still present among women who had evidence of prior exposure to HPV 16 or 18. Overall, the efficacy increased to 91 percent against HPV infection at two or three anatomical sites.
The HPV vaccine, Dr. Beachler stressed, cannot help clear current infections. “But it may provide some protection at one or more sites in women exposed to HPV prior to vaccination.”
The results, he added, support current recommendations for routine HPV vaccination starting at age 11 or 12, and vaccination through age 26 for those not vaccinated previously.
In addition to Cervarix, two other HPV vaccines are available in the United States: the quadrivalent vaccine Gardasil and the recently approved Gardasil9, which protects against seven cancer-causing types of HPV.