Predictors of HPV vaccine uptake: Do boys differ from girls?

Objective: The human papillomavirus (HPV) vaccine, which prevents strains of the virus that cause genital warts and cervical cancer, has been recommended as a routine vaccination for 11-12-year-old girls since 2007. In 2011, the recommendation was extended to include adolescent boys amidst recognition that HPV causes some cancers in males, as well as to promote herd immunity and prevent disease in females. This study aims to identify patterns of uptake among boys and determine whether predictors of HPV vaccination differ for boys and girls.

Methods: Data are from the 2011 National Immunization Survey – Teen, a survey of households with 13-17-year-old children that also contacts teens' vaccination providers. We assessed the bivariate relationship between socio-demographic characteristics and provider-reported HPV vaccination status (≥1 dose and ≥3 doses) separately among male and female adolescents. We then estimated the relationship with multivariate logistic regression, using interaction terms to detect differences by sex.

Results: Fifty-three percent of girls and 8.3% of boys had received at least one dose of the HPV vaccine. In bivariate analyses, black and Hispanic teens of both sexes had higher vaccine initiation rates than white teens. Lower household income, lower education level of the teen's mother, and provider recommendation for the vaccine were also associated with higher initiation rates. For boys, none of these characteristics was associated with completion of the three-dose series among those who had had at least one dose. For girls, HPV vaccine completion was associated with white race, higher family income, and higher level of mother's education.

In multivariate analyses, black and Hispanic teens had 50-67% higher odds of vaccine initiation compared to white teens. Household income above 300% of the federal poverty line (FPL) (vs. less than 100%), older age of the teen, having a check-up within the last year, and having a provider recommend the vaccine were also positively associated with vaccine initiation. The effect of provider recommendation was stronger for boys than for girls. Few characteristics were associated with HPV vaccine completion in the multivariate model.

Conclusions: In 2011, HPV vaccine uptake was quite low among boys, although the proportion of boys having received at least one dose of the vaccine had quadrupled since 2010. Black and Hispanic race/ethnicity and lower income were associated with higher rates of vaccine initiation among both boys and girls. Provider recommendation was a strong predictor of vaccination in all teens, but was even more important for boys.