National Trends in Parental Human Papillomavirus Vaccination Intentions and Reasons for Hesitancy, 2010-2015

"Although parental vaccination intent and knowledge improved over time, intent remains low and many parents still have significant concerns about HPV vaccination, even after series initiation."

Despite efforts to communicate the value, safety, and efficacy of human papillomavirus (HPV) vaccines, parental concerns contribute to their delay or refusal to vaccinate their children. In the United States (US), series completion rates are still far below the Healthy People 2020 goal of 80%, at 42% among females and 28% among males in 2015. This study was conducted based on the belief that understanding how vaccination intent and reasons for hesitancy have changed over time can inform healthcare providers' and public health practitioners' understanding of the impact of efforts to improve HPV vaccine uptake, why a large proportion of teens remain unvaccinated or undervaccinated against HPV, and how best to tailor messaging to address the changing landscape of concerns going forward.

Study participants included US residents aged 13-17 years with documented vaccination status who had received fewer than 3 doses of HPV vaccine whose parents responded to the National Immunization Survey-Teen, 2010-2015. Of the 76,971 participants, 63.0% were male and 58.8% were non-Hispanic white; 14.4 years was the median age.

The percentage of unvaccinated teens decreased between 2010 and 2015, from 91.7% to 66.9% among females and from 99.6% to 72.7% among males. In each year, the percentage of parents of unvaccinated teens reporting that they were "not likely at all" to vaccinate their teen against HPV was significantly higher than any other reported level of intent. Between 2010 and 2015, there was a significant decrease in the percentage of parents of females who were "not likely at all" to vaccinate (from 41.5% to 31.2%), and a significant increase in those "somewhat likely" to vaccinate their teens (from 16.3% to 22.0%). Between 2012 and 2015, there were no statistically significant changes in parental intent to vaccinate among parents of males. In 2015, parents of females (vs. males) were significantly more likely to report that their teen was "very likely" to be vaccinated (3.5 percentage point difference), and parents of males (vs. females) were significantly more likely to report that their teen was "not too likely" to be vaccinated (4.4 percentage point difference).

Among parents of both male and female unvaccinated teens, the most prevalent reason for HPV vaccine hesitancy in 5 of the 6 years analysed was due to the belief that the vaccine was not needed or necessary, including in 2015. The percentage of parents of females citing this reason significantly increased from 25.8% in 2010 to 32.7% in 2015. While "safety concerns/side effects" was the first (2010) or second (2011-2015) most prevalent reason for vaccine hesitancy among parents of females, the percentage citing this reason significantly decreased from 30.3% to 21.1% from 2010 to 2015. The percentage of parents of males reporting "safety concerns/side effects" as their main reason significantly increased from 7.3% to 14.8% between 2012 and 2015. Parents of females were significantly less likely than parents of males to cite a lack of a provider recommendation as their primary reason - suggesting that providers continue to more consistently make recommendations to females than males - and significantly more likely to report that that their teen was "not sexually active" or that they had safety concerns than parents of males.

The most commonly reported reasons among parents of undervaccinated teens were similar to those seen among parents of unvaccinated teens. These findings highlight the additional importance of follow-up HPV vaccination counseling with parents even after initiation, as these parents may still have concerns that should be addressed to support vaccination series completion. Of particular note is that a substantial proportion of parents cited HPV vaccine not being recommended as their main reason for hesitancy. Suggestions for reducing parental hesitancy and emphasising that additional doses are recommended - thus increasing series completion - include: proactively discussing HPV vaccination with parents after initiation; providing reminders by mail, phone, and electronically; scheduling visits for subsequent doses at the time of series initiation; and reducing missed opportunities to administer HPV vaccine during other types of healthcare visits (e.g., acute care).

Thus, the results suggest that parental attitudes may be a larger barrier to HPV vaccination initiation than to series completion, and that different interventions are needed to address both. Many of the common reasons for hesitancy that parents report have persisted over time and reflect modifiable factors that can be addressed. Strong, quality provider recommendations are critical for series initiation but should be paired with additional strategies such as follow-up counseling and reminder/recall systems to bolster series completion. In addition, the researchers suggest that messages to parents should convey the importance of vaccination, including the benefits of on-time vaccination at the recommended age and of series completion.