Going beyond the Individual: How State-level Characteristics Relate to HPV Vaccine Rates in the United States

"Given that gender, religiosity, political ideology, and education policies are predictors of HPV vaccine completion, the interaction and underlying mechanism of these factors can be used to address the underutilization of the HPV vaccine."

Despite efforts to increase uptake, such as communication campaigns and distribution of vaccines to uninsured and low-income individuals, human papillomavirus (HPV) vaccination coverage is drastically lower than other childhood vaccines in the United States (US). In order to explore opportunities to enhance HPV vaccine uptake, the aim of this paper is to study the combination of individual (e.g., gender, race) and macro-level factors (e.g., political environment, state religiously, sex/abstinence education polices) that potentially influence HPV vaccine completion rates, as limited evidence is available. The hope is that further understanding these relationships may not only broaden the evidence in the literature to consider influences beyond the individual but may also provide guidance to leaders and facilitators who have decision-making power in HPV vaccine-related activities.

A comprehensive database was developed using individual-level date from the National Immunization Survey (NIS)-Teen (2016) and state-level data collected from publicly available sources to analyse HPV vaccine completion. The analysis included 20,495 adolescents from 50 US states and the District of Columbia (DC).

The study showed that most states identified as highly religious, had a conservative political ideology, and were in support of abstinence education. In 2016, only DC and 2 states had enacted an HPV vaccine mandate; Rhode Island (70.8%) and DC (62.0%) had the highest HPV vaccine coverage rates in the US. Those with the lowest HPV vaccine coverage rates in 2016 were Wyoming, Mississippi, South Carolina, Utah, and Texas. These states were found to be more conservative and highly religious than states with the highest coverage rates. Little variation among these states regarding education polices and vaccine exemptions was observed.

Individual and state effects of HPV vaccine completion were teen gender-female (odds ratio (OR), 1.65; 95% confidence interval (CI),1.56-1.75), Hispanic teen race/ethnicity (OR, 1.52; 95% CI,1.36-1.69), non-Hispanic Black teen race/ethnicity (OR, 1.34; 95% CI, 1.18-1.51), HPV vaccination recommended by healthcare provide (OR, 3.57; 95% CI 3.24-3.92), and HPV vaccine mandate (OR, 1.65; 95% CI 1.16-2.35). A larger percentage of highly religious adults within a state had significantly lower rates of HPV vaccine completion (with by far, the largest effect estimate). Gender, political ideology, religiosity, and sex education policy were not found to have similar impacts on Tdap and measles, mumps, and rubella (MMR) vaccination rates as the HPV vaccine. Abstinence education, Centers for Disease Control and Prevention (CDC) funding (per capita), and public health governance were found to be non-significant model factors.

This study suggests that a state's sex and abstinence education policy, religiosity, and political ideology may be important correlates of HPV vaccine completion. Most literature focuses on the intent to vaccinate teens against HPV based on religious beliefs, yet few give insights on religious impact on HPV vaccine completion. In fact, the present study suggests an 11-fold decrease in HPV vaccine completion rates among states with a higher percentage of religious adults. If parents are religiously opposed to immunising their children against infectious disease such as tetanus or measles, the likelihood of vaccinating these teens for a sexually transmitted infection (STI) like HPV poses a challenge to vaccine completion rates. "By considering the religious climate, states with a denser religious population (e.g., Utah) can benefit from faith-based HPV vaccine interventions delivered by religious leaders to increase coverage rates."

The results also suggest that suboptimal utilisation of the HPV vaccine may be increased through HPV school-mandates by requiring teens to be vaccinated for school enrollment. Furthermore, although enactment of sex education-only policies showed significance on HPV vaccine completion rates in this analysis, on average, states with both sex and abstinence education policies only had a slightly higher HPV coverage rate compared to states that had not enacted any education policies. This finding suggests that other contextual factors are driving HPV vaccine completion in states that do not have either policy in place.

As shown in other studies, the results indicate that females are more likely than males to complete the HPV vaccine series. Several efforts are shifting the mentality of HPV as a female-specific disease, including media campaigns that incorporate messages around male vaccination, the addition of males to the CDC's Advisory Committee on Immunization Practices (ACIP) HPV vaccine recommendations in 2010, and a growing body of evidence of the burden of disease in both males and females. Further, the results indicate that healthcare providers play a major role in HPV vaccine completion rates. Gender bias among healthcare providers' recommendations could also be influencing HPV vaccination rates among males. This further stresses the importance of provider recommendation for HPV vaccine completion, regardless of gender, to achieve desired coverage rates.

In the researchers' estimation, "further research should consider the complexity of the political and religious environment as well as other state-level policies [that] must be considered when trying to the address the underutilization of this cancer prevention vaccine." More broadly: "Further studies need to continue to identify state and local-level factors that contribute to HPV vaccine uptake and adherence as well as understand the underlying mechanisms of these factors within states of high and low HPV vaccine coverage rates. An in-depth case analysis of these states may provide insight on effective strategies, initiatives, and policies along with overcome challenges and barriers to serve as a guidance for other states and better inform HPV vaccine interventions."