New federal data show Rhode Island is having unparalleled success immunizing teenagers with a shot that has been a hard sell elsewhere — the vaccine against HPV, human papillomavirus.
Rhode Island health officials sparked a firestorm last year by requiring that students get the HPV vaccine before entering seventh grade. The mandate was in effect for only the last few months of 2015, and applied to children younger than those in the federal study, a survey conducted in 2015 and released Thursday.
Still, Rhode Island health officials said they believe the requirement contributed to the surge in adolescent vaccinations — and Massachusetts officials are watching the Ocean State's experience as they seek to improve their own record.
HPV vaccination rates among Massachusetts teenagers were higher than the national average in the 2015 survey but still more than 10 percentage points behind Rhode Island, which led the nation.
HPV is a sexually transmitted disease that, years after infection, can cause cancers of the cervix, anus, penis, head, or neck. The vaccine, introduced in 2006, is one of three recommended for adolescents — but the only one that most states don't require for school entry.
Acceptance of the HPV vaccine has lagged far behind that of other recommended vaccines, amid uneasiness over teenage sexuality and, sometimes, misinformation about the vaccine's risks. Also, three doses are required, and adolescents don't see their doctors as regularly as do younger children.
The 2015 data, from the US Centers for Disease Control and Prevention, show that nationwide, only 42 percent of girls age 13 to 17, and 28 percent of boys in that age group had received the three doses needed to confer immunity.
In Rhode Island, 68 percent of girls and 58 percent of boys had received all three doses, by far the highest in the nation and a significant increase over 2014.
The Rhode Island school mandate "definitely was a factor" in the state's high vaccination rates in 2015, said Tricia Washburn, chief of the Rhode Island Health Department's immunization office.
Although most seventh-graders are younger than the students included in the CDC survey, the school requirement raised awareness of the vaccine's availability and importance, Washburn said.
The state took other steps to promote the vaccine, including advertising HPV immunization, employing a physician-consultant who advised pediatricians on offering the vaccine, and expanding the in-school vaccination program to include middle schools.
Nearly 400 middle-school students received HPV shots in school during the 2015-2016 year.
In Massachusetts, 53 percent of adolescent girls and 35 percent of boys received the shots.
The HPV vaccine rate for Massachusetts increased slightly since 2014, but not enough to be statistically significant. Kevin Cranston, director of the state's Bureau of Infectious Diseases, said state health officials are eager to learn from the Rhode Island experience but are not sure whether the CDC data reflect the mandate's effects.
Massachusetts has no current plans to institute a similar school requirement.
Instead, Massachusetts health officials are working at making HPV vaccination easy and routine.
A policy adopted Nov. 1 makes the vaccine free to everyone; the doses are purchased by the state and delivered to pediatricians' offices along with other recommended vaccines. Previously, doctors had to seek reimbursement from insurers for this vaccine.
Massachusetts has also tackled another problem occurring around the country: Doctors, although supportive of the vaccine, tend not to recommend it as strongly as other vaccines.
Dr. Sean Palfrey, who leads the immunization initiative of the Massachusetts chapter of the American Academy of Pediatrics, said pediatricians would often tell parents something like, " 'Your child is 11 today. There are two vaccines we normally give out, and would you like this third one which prevents a sexually transmitted disease?' That was the problem."
Massachusetts health officials have encouraged doctors to treat vaccinating against HPV as a routine part of health care.
Dr. John Snyder, an Amherst pediatrician who is active in vaccine promotion, noted another challenge: "Because this is associated with sexuality, emerging sexuality in children, it touches on some areas of discomfort in parents."
But the goal is to protect children long before they are at risk for infection, Snyder said. HPV is highly prevalent, infecting as many as half of all teenage girls, and the vaccine won't work once someone is infected, he said.
Palfrey and Snyder said they favor school mandates such as Rhode Island's, but know they are politically difficult. Other measures, such as allowing pharmacies to vaccinate children, might be more effective, Palfrey said.
In addition to Rhode Island, only Virginia and the District of Columbia require HPV vaccination for schoolchildren. The results are mixed. D.C. has one of the nation's highest HPV vaccination rates, while Virginia is well below the national average.
When the school mandate was introduced, Rhode Island already had the highest rate of HPV vaccination in the nation. But a group of parents objected loudly to making HPV vaccine a requirement for starting school, noting that unlike measles and mumps, HPV is not transmitted in the classroom.
The debate also opened a forum for vaccine opponents who circulated stories of harm from the HPV vaccine — stories that doctors and health officials denounce as false.
The Rhode Island school mandate is not ironclad. Parents can excuse a child from the requirement by signing a form saying they object on religious grounds, and the Health Department advised schools not to exclude any child for lack of vaccination, even those who don't submit the form.
Religious exemptions — usually about 1 percent — increased to 4 percent for the HPV vaccine in 2015, Washburn said.
Aimee Gardiner, director of Rhode Islanders Against Mandated HPV Vaccinations, said she remains confident that opponents will eventually eliminate the school-entry requirement in Rhode Island.
Bills to do so in the last legislative session died without a vote, but three dozen opponents packed the hearing room, she said.
Felice J. Freyer can be reached at email@example.com.