Predicting a child's future is a near impossible task - today's straight-A student may not become tomorrow's doctor, and the school-yard bully may actually grow up to become a member of the Peace Corps.
So why should an adolescent's sexual behavior- or lack thereof - determine whether or not she gets vaccinated against the human papillomavirus, to protect against future HPV infection? It shouldn't, say researchers at the University of Michigan C.S. Mott Children's Hospital's Child Health Evaluation and Research (CHEAR) Unit.
The study, set to appear in the July issue of the journal Pediatrics, finds women who were sexually active as adolescents were just as likely as women who were not sexually active during their youth to get HPV as adults.
"Using risk factors as a means to determine who should get the HPV vaccine is not a good strategy. In our study, all women who eventually became sexually active at some point had an equivalent risk of getting HPV," says study lead author Amanda F. Dempsey, M.D., Ph.D., MPH, a member of the CHEAR Unit in the U-M Division of General Pediatrics.
These findings, Dempsey says, support the Centers for Disease Control and Prevention's Advisory Committee on Immunizations Practices recommendation for universal vaccination for all women ages 11 to 26, regardless of sexual experience.
Much of the confusion over whether or not to vaccinate a patient stems from conflicting recommendations. While the ACIP advocates for universal vaccination, the American Cancer Society recommends vaccinating all females younger than 18, and selectively vaccinating women ages 19 to 26 based on an informed discussion between the patient and her doctor about sexual history.
The price of the vaccine is also a factor. With each dose costing approximately $120 - along with high up-front costs to stock the vaccine, inconsistent coverage from government programs and low levels of reimbursement from private insurance - many states are struggling to provide the vaccine to all eligible girls and women.
For those reasons, many clinicians are targeting the HPV catch-up vaccination to only girls and women they deem to be at the greatest risk for acquiring HPV. Previous studies of sexually active adolescents and young adults identified specific sexual partnerships, behavioral and sociodemogrpahic characteristics associated with increased risk for HPV infection.
The problem, Dempsey says, is that those studies only looked at women currently infected with HPV, and retrospectively analyzed potential risk factors for infection.
"Few studies have evaluated the ability of specific risk factors to predict future HPV infection prospectively," says Dempsey. "This is an important distinction, given that, to be effective, the HPV vaccine must be provided before vaccine type-specific infection occurs."
For their study, Dempsey and her colleagues selected six high-risk behaviors that have been shown in other studies to be associated for sexually active women with a higher risk of HPV - the number of sexual partners, history of having an older male sexual partners and/or a new sex partner with the past year, illegal drug use, history of sex while impaired by drinking, and regular use of cigarettes/alcohol. For virgins the team also assessed risk factors found in other studies to be associated with the acquisition of other sexually transmitted diseases, and early sexual activity.
Of the risk factors evaluated during adolescence, none were found to be associated with future HPV infection. Among sexually active adolescents, only a history of having sex while impaired by alcohol was associated with increased odds of testing positive for vaccine-type HPV as a young adult.