WEDNESDAY, July 29, 2020 (HealthDay News) -- More than a decade of research has shown that the human papillomavirus (HPV) vaccine protects against a host of cancers, yet a new study finds that only half of American teens complete the multiple-shot regimen.
Why? Researchers discovered that many parents still harbor safety concerns about the vaccine, even though it guards against 90% of all cervical and anal cancers.
Using data from the 2017-2018 National Immunization Survey, researchers analyzed responses from parents or caregivers of more than 82,000 U.S. teens.
"We wanted to understand the dynamics of HPV vaccination, and why HPV vaccine rates are suboptimal despite the vaccine being in the market for over 10 years now," explained study author Kalyani Sonawane, an assistant professor at the University of Texas Health Science Center at Houston.
Sonawane and her team concluded that 7.7 million U.S. teens were not vaccinated against HPV in 2018.
The survey responses also revealed that more than half of the parents with unvaccinated teens had no intention of vaccinating them in the future.
"Among those who do not want to vaccinate against HPV, safety emerged as a main concern," Sonawane said. "A lot of parents of these teenagers who had received zero doses said that the main reason they do not wish to vaccinate their child is because they have safety concerns about the vaccine."
It is likely that the anti-vaccination movement is contributing to parent hesitancy about the HPV vaccine, according to the researchers.
They also compared the responses between different states, finding that states with the lowest rates of HPV vaccinations, such as Mississippi and Wyoming, also had high parental hesitancy rates.
Sonawane noted that these states could face a high burden of HPV-linked cancers in the future.
The HPV vaccine is a two-dose or three-dose series, depending on when a patient receives the first dose.
The U.S. Centers for Disease Control and Prevention recommends two doses of the vaccine if the first dose is given before age 15, or three doses if the series is started between ages 16 and 26.
The second dose is recommended six months to a year after the first, and only the full series ensures protection.
The researchers estimated that 2.2 million teens in the United States have only received a partial HPV vaccination.
Of those teens who only received the first dose of the vaccine, 1 in 4 parents said they did not intend to complete the series.
Many of these parents said their teens didn't get the second dose because their health care providers didn't reach out to them, the researchers found.
"The main reason that emerged among these parents was that they never received a recommendation for their teen," explained Sonawane. "A lot of times the patients or the provider fail to follow up with the teens and say, 'Hey, you need the second dose or third dose to complete the HPV vaccine series and to have enough immunity to prevent HPV infection in the future.'"
Previous research has shown that a provider recommendation is the most reliable way to ensure vaccination, but this study revealed that it might not be enough.
A full 6 of 10 parents with an unvaccinated teen who had received a recommendation from their provider said they still would not vaccinate. The most common reason was worries about the vaccine's safety.
The findings were published recently in The Lancet Public Health journal.
Debbie Saslow, director of HPV and gynecologic cancer at the American Cancer Society, pointed out that the study only looked at those who aren't vaccinated.
Despite the concerns this study raises, she emphasized that many American teens are now vaccinated against HPV.
"It's also important to look at the counterpoint, which is that most parents do vaccinate their kids against HPV," Saslow said.
Despite the findings that some parents wouldn't vaccinate their teens even with a provider recommendation, Saslow said the primary approach in HPV vaccine advocacy is working with providers and health systems.
"If a parent says, 'I read on Facebook that the vaccine has this side effect,' then the provider has the opportunity to say, 'Actually, that's misinformation, and let me explain to you how safe this vaccine is,'" Saslow said. "The provider is most parents' most trusted source of information, so that's why we've really focused on that."
Sonawane and her team also stressed the importance of training providers to remind their patients to get vaccinated, and to be prepared with clear answers to debunk any vaccine safety myths.
There's more about the HPV vaccine at the U.S. Centers for Disease Control and Prevention.