Diane D. Davey, MD
January 2018—Diane Harper, MD, MPH, and Leslie DeMars, MD, provide an extensive review of the efficacy of available FDA-approved HPV vaccines in different age groups and describe immunogenicity findings in particular (Gynecol Oncol. 2017;146:196–204). The World Health Organization and the Centers for Disease Control and Prevention recommend a two-dose vaccine for younger children due to high rates of seroconversion and antibody titers in this age group. Girls age 15 and older should continue to get three doses.
Immunogenicity (immunologic non-inferiority) is now an agreed endpoint for individuals ages 16–26 after persistent type-specific HPV infection protection is demonstrated. Cervarix, which is predominantly used in countries other than the U.S., appears to sustain high antibody titers to HPV types 16 and 18 for at least 10 years. Areas with extensive Gardasil use have demonstrated reduced numbers of HPV16/18 infections; however, both Gardasil and Gardasil9 (which has largely replaced Gardasil) demonstrate rapid loss of seropositivity to HPV types 18 and 45. A Gardasil9 booster does not appear to be helpful in women who have previously been vaccinated with Gardasil. The authors also review studies on use of a single-dose vaccine administration.
While the number of abnormal Pap tests and colposcopy procedures has decreased in countries with high rates of vaccine administration, countries that achieve higher vaccination rates tend to be higher income with less invasive cervical cancer. The percentage of targeted women worldwide who are adequately vaccinated remains low: less than two percent of females ages nine to 45, and nonexistent in countries where the cervical cancer rate is highest. Given that current vaccines do not protect against all oncogenic HPV types and may show variable loss of HPV type-specific seropositivity over time, women who are vaccinated must continue to receive cervical cancer screening indefinitely.
Dr. Davey, a member of the CAP Cytopathology Committee, is associate dean of graduate medical education, University of Central Florida College of Medicine, Orlando, and practices at the Orlando VA Medical Center.