The cancer-preventing vaccine Gardasil, which protects against HPV strains that cause most cervical cancers and many other anogenital cancers, has had a fraught history in the public eye.
Even though it’s an easy and effective way to prevent a cancer that kills more than 4,000 women in the U.S. every year, less than 40 percent of eligible teenage girls had received the full course of the vaccine in 2013. And it’s not entirely clear why so few get vaccinated.
But a new study is shedding light on who is getting the HPV vaccine in the U.S. The study, published Thursday in the journal Cancer Epidemiology, Biomarkers & Prevention, examined the racial and socioeconomic factors influencing vaccination decisions by looking at community and geographic data, such as ZIP code, in addition to individual demographics.
Researchers found that HPV vaccine uptake is highest in high poverty and predominantly Hispanic communities. In fact, Hispanic families living in predominantly non-Hispanic white communities were no more likely than their white neighbors to choose the vaccine.
So it’s not just who you are, but where you live, that influences your choice to vaccinate, said Dr. Kevin Henry, a health outcomes researcher at Temple University and Fox Chase Cancer Center who led the study.
“We have this cancer-prevention vaccine that is severely underutilized in the United States,” Henry said. “We need to explore ways to improve targeted public health messaging to improve this vaccine among the sociodemographic groups that are less likely to receive it, which we’re finding are the higher income groups.”
Fred Hutchinson Cancer Research Center’s Dr. Denise Galloway, a virologist whose discoveries helped lay the groundwork for Gardasil and other HPV vaccines, said it’s nice to see that some communities are doing a bit better than average, but there’s still work to do in all neighborhoods in the U.S.
“It’s great that [two-thirds] of Hispanic teens are getting at least one dose,” Galloway said. “But it’s still not where we need to be.”
Henry and his colleagues parsed through data from the National Immunization Survey, a federal database to track childhood vaccinations throughout the country. The researchers looked at HPV vaccine uptake in more than 20,000 teenage girls aged 13 to 17 years old in 2011 and 2012.
For simplicity’s sake, they asked how many girls had received at least the first dose of the three-dose series for the current study, Henry said, although they also plan to look at dose-completion in a future study. Overall, slightly more than half of teenage girls in the U.S. got one or more HPV shots.
Hispanic girls living in predominantly Hispanic communities were the most likely to have received the vaccine — 69 percent of these girls had received at least the first dose of the 3-dose vaccine series. Families living in majority non-Hispanic white communities were the least likely, with only 50 percent having initiated the vaccine series, and 54 percent of those in non-Hispanic black neighborhoods had initiated.
Those results match earlier reports showing that at an individual level, Hispanic girls were far more likely to get the HPV vaccine than white girls. But the finding that community matters is new, Henry said: The trend for Hispanic girls living in predominantly white neighborhoods seemed to echo their surroundings — only 49 percent had initiated vaccination.
There are several reasons that neighborhood could matter, Henry said, although they haven’t yet dug into the reasons behind this disparity. The U.S. Centers for Disease Control and Prevention operates Vaccines For Children, a program that gives free vaccines to children from low-income families.
It’s possible that program is doing a particularly good job in Hispanic neighborhoods, Henry said, which tend to also be poorer neighborhoods. The researchers did see a correlation between neighborhood poverty and vaccine uptake — neighborhood poverty also correlates with higher rates of vaccine initiation. But it’s not purely a question of economics, Henry said, because predominantly black neighborhoods also tend to have high poverty rates and those communities didn’t have significantly higher vaccine uptake.
Hispanic women have the highest rates of cervical cancer and cervical cancer deaths of any racial or ethnic group in the U.S., so it’s also possible that care providers in their communities are doing a good job getting the prevention message out, Henry said. But there seems to be something about vaccines that bucks the typical American health disparities trend.
“Cervical cancer screening is lowest amongst the poor; breast cancer screening is lowest among some of the poorer populations. The Pap smear is low amongst Hispanics — yet you see the opposite here,” Henry said. “In itself that’s very interesting.”
In a follow-up study, Henry and his colleagues aim to address the reasons behind the community disparity through answers that survey participants gave as to why they got the vaccine (or didn’t).
“That part is critical,” Henry said. “It’s good to look at these national surveys to try to get some context, but we want to really delve into the cultural values, what made them decide not to or what made them decide to get [the vaccine].”
Fred Hutch public health researcher Dr. Victoria Taylor, who studies cancer prevention and screening in minority populations, called the ZIP code-based research “an interesting study.” However, some of Taylor’s work has suggested that national surveys might not fully capture certain underserved populations.
In a study published in 2014, Taylor collaborated with Kaiser Permanente’s Dr. Gloria Coronado to look at HPV vaccination rates among teenage Latinas in certain pockets of the country. The researchers surveyed Hispanic families in Washington state’s Yakima Valley, a predominantly rural and agricultural community with a high percentage of migrant farm workers.
Using data collected in 2009, they found that only 37 percent of the 90 families surveyed in Yakima Valley had received at least one dose of the vaccine, a rate lower than the 2009 national averages even though nationwide surveys have consistently shown Latina girls to have higher than average HPV vaccination rates.
The Yakima Valley Latino community and those in other regions surveyed by Taylor’s collaborators in the 2014 study — Los Angeles County, Houston and the Lower Rio Grande Valley in Texas — tend to have poorer access to health care than the average Hispanic U.S. community, the researchers wrote.
Whatever the reason, “HPV vaccination initiation and completion rates remain low among all population groups,” Taylor wrote in an email.
In Henry’s study, having a care provider recommend the vaccine was one of the strongest indicators that a family would choose to vaccinate — that’s consistent with previous findings as well. And a recent survey of U.S. physicians found that many are not following the CDC’s guidelines of how to recommend the HPV vaccine to their patients, with more than a quarter saying they don’t strongly endorse the vaccine or recommend it in a timely fashion.
So it’s possible that education needs to start with the doctors, not the families themselves. In that survey, nearly 60 percent of doctors recommended the vaccine more strongly to patients they deemed at high risk of HPV or HPV-associated cancers. But that’s exactly the wrong approach, Henry said, and it’s not the one recommended by federal guidelines.
“It’s important to target high-risk populations, but from a vaccination standpoint when you think about herd immunity, it’s important across the board to have high vaccination rates, not just in certain populations,” he said.
Rachel Tompa is a former staff writer at Fred Hutchinson Cancer Research Center. She has a Ph.D. in molecular biology from the University of California, San Francisco and a certificate in science writing from the University of California, Santa Cruz. Follow her on Twitter @Rachel_Tompa.