SOURCES: Jason Schwartz, Ph.D., research associate, bioethics, Princeton University, Princeton, N.J.; Jessica Kahn, M.D., M.P.H., professor, pediatrics, Cincinnati Children's Hospital Medical Center, Ohio; Fred Wyand, director, communications, American Sexual Health Association, Research Triangle Park, N.C.; July 14, 2015, Journal of the American Medical Association
TUESDAY, July 14, 2015 (HealthDay News) -- Almost a decade after the HPV vaccine was first recommended for girls, only two U.S. states and Washington, D.C., require the immunization, a new study finds.
What's more, researchers say, most U.S. states do require other vaccines routinely recommended for preteens and teenagers -- the vaccines against hepatitis B, chickenpox and meningitis.
"Our study can't answer the question of why," said Jason Schwartz, a bioethics researcher at Princeton University in New Jersey. "We can only show that there's a stark difference between HPV and these other vaccines."
But Schwartz speculated that states may not want to revisit the controversy that arose with HPV vaccine approval in 2006.
At the time, numerous states did propose legislation to require the vaccine. But that drew opposition from wary parents and even public health experts, who said it was too soon for mandates.
"It's a controversy that was unique to the HPV vaccine," Schwartz said.
The study findings appear in the July 14 issue of the Journal of the American Medical Association.
The HPV vaccine protects against several strains of the human papillomavirus that cause genital or anal warts and can eventually lead to cancer. Most cervical cancers are caused by HPV, and the virus can also contribute to vaginal, anal and vulvar tumors.
Since 2007, U.S. health officials have recommended that all girls ages 11 and 12 receive the HPV vaccine, and that teenagers and young women up to age 26 get "catch-up" shots if they missed the earlier window. The advice was later extended to boys and young men.
Right now, though, Virginia and Washington, D.C. are the only jurisdictions that require HPV vaccination. In August, Rhode Island will join them, Schwartz said.
In contrast, 29 states and the District of Columbia require the meningococcal vaccine, which protects against serious infections of the brain, spinal cord and blood, the researchers said in background notes. Forty-seven states and D.C. require the vaccine against hepatitis B, which, like HPV, is sexually transmitted.
All states require kids to be vaccinated against chickenpox, the study authors added.
And it's not just because those vaccines have been around longer, Schwartz's team found. When the hepatitis B vaccine was at its eight-year mark, for example, 36 states and Washington, D.C. had made it mandatory.
"The difference is striking between state-level requirements for the HPV vaccine and other recently recommended adolescent vaccines," said Dr. Jessica Kahn, a professor of pediatrics at Cincinnati Children's Hospital Medical Center.
If more states made the vaccine a requirement, that would help boost the low rate of HPV vaccination nationwide, said Kahn, who was not involved in the study.
In 2013, only 38 percent of U.S. teenage girls and 14 percent of boys had received all three doses of the HPV vaccine, according to the U.S. Centers for Disease Control and Prevention.
There are three vaccines that can prevent infection with certain cancer-related strains of HPV: Cervarix, which protects females against genital warts and cervical cancer; and Gardasil and Gardasil 9, which protect against warts and anal cancer in both sexes, as well as vaginal and vulvar cancers, the CDC says.
The vaccines cost about $400 for all three doses, but most insurance plans and Medicaid cover them.
Schwartz said he did not think cost was a major barrier to state requirements for HPV vaccination. Some other vaccines that are required, such as the meningococcal jab, are not cheap, he pointed out.
"Strong" recommendations from doctors would also help improve HPV vaccination rates, Kahn said, as would efforts to make more parents aware of the potential benefits of vaccination.
Some parents worry that HPV vaccination gives kids tacit approval to have sex, Schwartz said. "But we now have clear evidence, from a number of studies, that vaccination does not encourage sexual activity," he said.
Schwartz agreed that state mandates are not the only way to boost HPV vaccination rates.
"But I also think it may be time to start thinking about requirements, and how they could raise (HPV vaccine) coverage," he said.
According to Fred Wyand, communications director for the American Sexual Health Association, mandates are "obviously" an effective way to boost vaccination rates.
But even without laws, Wyand said, HPV vaccination needs to be seen as "normal and routine," and doctors should promote it that way. Some parents, he noted, mistakenly believe their children are unlikely to need protection against HPV.
"The majority of sexually active individuals will have one or more HPV infections in their lifetime," Wyand said, "and HPV cuts across all demographics."
The U.S. Centers for Disease Control and Prevention has more on HPV vaccination.