Why the HPV vaccine has stalled

Doctors had hoped that the twin scourges of cervical cancer and genital warts would end after the 2006 introduction of Gardasil, a safe and effective vaccine against human papilloma virus (HPV), which causes both diseases. But so far, fewer than 25 percent of eligible women and girls have received even one dose, and proposals to require vaccinations of preteens have met with fierce resistance.

To understand why, epidemiologist Alison Galvani, an assistant professor at the School of Public Health, and her colleagues surveyed 326 parents of eligible preteens and 286 college students about their perceptions of Gardasil's risks and benefits. While both groups felt the vaccine could prevent many instances of genital warts—and the more than 10,000 cases of cervical cancer a year in the United States alone—a majority of parents and students also thought vaccination would lead to increased promiscuity. Indeed, the students thought vaccinated women would go on to have 1.8 times as many sexual partners as unvaccinated ones. Gardasil's cost also emerged as prohibitive. Even with health insurance, the average cost of the three required vaccinations is $181. (Side effects were a minor concern.)

Galvani and her team developed a mathematical model for evaluating ways to boost vaccination rates. (The results appear in the December 2 Proceedings of the National Academy of Sciences.) Because there is no evidence that changes in sexual behavior will occur as a result of vaccination, they argue, a targeted public health education campaign would likely counter fears of increased promiscuity. And a little financial aid wouldn't hurt.