ANN ARBOR, Mich. - Three years after the vaccine to prevent human papillomavirus (HPV) was approved for use in the United States, researchers are discovering that usage rates for those targeted to take it is low.
HPV is a leading cause of cervical cancer among women. The HPV vaccine is only useful if provided prior to exposure, which generally happens at the onset of sexual activity.
In a new study appearing this month in the journal Vaccine, lead author and pediatrician Amanda Dempsey, M.D., PhD, MPH , describes an analysis of the factors associated with adolescent HPV vaccine use and reports variation by insurance type, race, type of visit, and whether the health care provider was a pediatrician, gynecologist or family medicine doctor.
The study looked at vaccination data from January 2007 through March 2008, coinciding with the first 15 months of HPV vaccine availability in university-based health system clinics where adolescents in the study were seen as patients.
The purpose of the study was to define adolescent populations with low usage to understand what types of interventions might be most effective for improving vaccination rates in the future.
Researchers looked at HPV vaccination rates among nine to 18 year-old patients seen at 20 university-affiliated outpatient clinics in southeast Michigan in three medical specialties - family medicine, pediatric and gynecological clinics. The study found:
- Overall HPV vaccine use was low among adolescents. Among girls who were eligible to have received all three doses in the vaccination series, only 15 percent did so. This finding is consistent with a national study showing low vaccine series completion among 13 to 17 year-olds in 2007.
- Even though overall uptake of the vaccine among adolescents was low, once the vaccine series was initiated there was a relatively high likelihood they would receive all three doses, with more than three quarters of those eligible getting second and third doses.
- Despite recommendations from the Advisory Committee on Immunization Practices for universal vaccination of all 11-12 year old females against HPV, this age group was significantly less likely to initiate the vaccine series when compared to 13-15 year-olds, or those over the age of 16. However, among girls that did initiate the series, all three age groups had a similar likelihood of being fully vaccinated with all three doses.
- Gynecologists were less likely to initiate the vaccine series than pediatricians or family practitioners. However, after the three-dose series began, there were no statistical differences in series completion among patients seen at each medical specialty.
- Most adolescents received the first dose of vaccine at a "well child check up." Subsequent doses of vaccine were typically provided at "immunization only appointments," where the patient receives the vaccine from a nurse and has no interaction with a doctor. However, this pattern varied by age. The older an adolescent, the more likely they were to receive second and third doses at a "sick visit" with the doctor.
Researchers also found disparities in series completion by race and insurance status. The fact that minorities and those with public health insurance were less likely to be completely vaccinated raises questions about the degree to which HPV vaccination will impact cervical cancer rates in the U.S. since these groups are already known to be at higher risk for developing cervical cancer, Dempsey says.
Results suggest continued outreach to adolescents is needed in order to improve HPV vaccination, and particularly strong efforts are needed to increase vaccination among underserved minorities, those who are socio-economically disadvantaged, and pre-adolescents (11 to 12-year-olds).
In addition, "starting the series seems to be critical element in the overall HPV vaccination process," says Dempsey. "Finding ways to convince families to start is really the key."
Additional authors: Lisa Cohn, M.S., Vanessa Dalton, M.D., M.P.H., Mack Ruffin, M.D., M.P.H., all of the University of Michigan
Funding: Clinical Science Scholars Program at the University of Michigan
Disclosures: Dempsey is a consultant for Merck on male HPV vaccination
Journal reference: DOI is 10.1016/j.vaccine.2009.10.133