ew data on vaccination rates among U.S. teenagers provide some heartening news — but also pose a bit of a mystery.
The report, from the Centers for Disease Control and Prevention, shows parents of teenagers are in the main following the CDC’s advice and keeping their children up to date on vaccines that should be administered in the early teens.
But the 2016 survey revealed big differences in the rates of teenagers who are vaccinated with some but not all recommended vaccines, depending on whether they live in cities or more rural locations. And that fact is puzzling the CDC scientists who analyzed the data, published Thursday in the CDC journal Morbidity and Mortality Weekly Report.
Both rural and urban kids in large numbers were vaccinated against tetanus, diphtheria, and pertussis —a combined vaccine known as Tdap. In fact, 88 percent of teens received that vaccination, with nearly equal uptake rates among urban and rural adolescents.
But the vaccination rate against human papillomavirus, or HPV, was 16 percentage points lower in rural areas than urban areas. These sexually transmitted viruses can cause a number of cancers. And though one might be tempted to assume that rural parents were less inclined to vaccinate their children against a sexually transmitted virus, it was not the only kind of vaccine for which there was a stark rural-urban divide. The rate of rural teens who received the recommended first dose (of two) of vaccine against meningococcus, which can cause fatal meningitis, was nearly 10 percentage points lower than it was for urban teens.
The senior author of the article said the CDC isn’t sure what’s going on, but it wants to figure it out.
“It’s an area we’re definitely going to be looking into this year to better understand what might be contributing to those results,” said Shannon Stokley, associate director for science in CDC’s immunization services division.
The data were drawn from the 2016 National Immunization Survey-Teen, which focused on vaccination behavior among nearly 20,500 adolescents 13 to 17 years old. The survey is conducted annually.
Stokley said cost is probably not the reason why some rural parents are getting their children immunized with Tdap vaccine, but not HPV or meningococcus. The Affordable Care Act mandates that private insurance cover vaccination costs, and children in low-income families can get free vaccines through the federal Vaccines for Children program.
“Most children are covered, either through insurance or through the VFC program. Even when we’ve interviewed parents cost has not been an issue that has come up as a barrier,” she said. “I’m not sure at this time if we have a leading hypothesis of what’s behind this. But it’s something we want to get to the bottom of and understand.”
Though the HPV vaccine is highly effective, it was first recommended only for girls; in 2011, the CDC recommended it for boys as well.
Public health officials had thought a vaccine that protected against cancers — cervical, anal, and others — would be in big demand, but some parents worried it would be viewed by teenagers as a license to have sex.
Over the last decade, however, HPV vaccination rates have risen. The 2016 data show that about 60 percent of teens get at least one of the two recommended doses of HPV vaccine.
“HPV vaccination is the new norm for boys and girls in the United States,” said Noel Brewer, a professor of health behavior at the University of North Carolina who was not involved in the CDC study. “The majority of parents are getting HPV for their kids. That’s important.”
Also important: The 2016 data show that the gap is closing between the number of girls and boys who are vaccinated. “We’re making a lot of progress with the boys and actually getting very close to where we are with girls. And so that’s really exciting to see,” Stokley said.
Research that Brewer and others have conducted shows that the way doctors approach the issue of HPV vaccination influences whether parents will agree to let their kids get the shots. Firm recommendations that it’s time to get Tdap, HPV, and meningococcus vaccines — messages that convey that the doctor strongly urges all these vaccines — have been shown to result in more agreement from parents.
Conversely, the research shows that doctors who anticipate that parents might object to HPV vaccination and as a result approach the parents with uncertainty actually underscore parental concerns in a way that leads to lower acceptance rates.
Brewer, who heads a national HPV vaccination roundtable for the American Cancer Society, has a theory on why there’s a difference between urban and rural HPV and meningococcal vaccination rates. If he’s right, it’s not because rural doctors aren’t promoting them hard enough. It may be because some urban doctors are working extra hard.
Brewer thinks some urban doctors may more assertively recommend all available and free preventative health care options to children from low-income families when they see them because they know these kids — whose families may not have health insurance — will only infrequently see doctors. In other words, the doctors assume each encounter may be the only chance to administer recommended vaccinations, and they urge parents to accept them.
Delving into what’s happening will help public health officials devise more effective advice for all doctors on how to persuade parents to give their teenagers the full complement of recommended vaccinations, Stokley said. Part of the goal is to get more of the teenagers who have received one shot of HPV vaccine back to get the second dose. (Three doses are recommended if teenagers only begin the course of immunizations when they are 15 or older.)
“We’re really encouraged to see that over 60 percent have started the series,” said Stokley. “And we need to work to get the adolescents back in for the remaining doses.”