title: Human Papillomavirus Vaccine Initiation among 9-13-Year-Olds in the United States.
abstract: OBJECTIVE
  The quadrivalent and 9-valent human papillomavirus (HPV) vaccines are licensed for administration among 9-26-year-old males and females, with routine vaccination recommended for 11-12-year-olds. Despite the availability of the vaccine at younger ages, few studies have explored vaccine uptake prior to age 13, and national HPV vaccination surveillance data is limited to 13-17-year-olds. Our objective was to examine rates and predictors of HPV vaccine initiation among 9-13-year-olds in the United States.
  
  
  METHODS
  A national sample of mothers of 9-13-year-olds in the United States (N=2,446) completed a 2014 Web-based survey assessing socio-demographic characteristics, child's HPV vaccination history, provider communication regarding the vaccine, and other attitudes and behaviors pertaining to vaccination and healthcare utilization. The main outcome measure was child's initiation of the HPV vaccine (i.e., receipt of one or more doses).
  
  
  RESULTS
  Approximately 35% of the full sample and 27.5% of the 9-10-year-olds had initiated HPV vaccination. Females were more likely than males to have initiated HPV vaccination by the age of 13 but not by younger ages. Strength of health provider recommendation regarding HPV vaccination was a particularly salient predictor of vaccine initiation.
  
  
  CONCLUSIONS
  Approximately a third of children may be initiating the HPV vaccine series before or during the targeted age range for routine administration of the vaccine. Because coverage remains below national targets, further research aimed at increasing vaccination during early adolescence is needed. Improving providers' communication with parents about the HPV vaccine may be one potential mechanism for increasing vaccine coverage.
authors.affiliation: Indiana University School of Medicine, Dept. of Pediatrics, Indianapolis, IN, 410 West 10 Street, Suite 1001, Indianapolis, IN, 46202, USA.
authors.forename: Kelly L
authors.initials: KL
authors.lastname: Donahue
authors.affiliation: Indiana University School of Medicine, Dept. of Pediatrics, Indianapolis, IN, 410 West 10 Street, Suite 1001, Indianapolis, IN, 46202, USA.
authors.forename: Kristin S
authors.initials: KS
authors.lastname: Hendrix
authors.affiliation: Indiana University School of Medicine, Dept. of Pediatrics, Indianapolis, IN, 410 West 10 Street, Suite 1001, Indianapolis, IN, 46202, USA.
authors.forename: Lynne A
authors.initials: LA
authors.lastname: Sturm
authors.affiliation: Indiana University School of Medicine, Dept. of Pediatrics, Indianapolis, IN, 410 West 10 Street, Suite 1001, Indianapolis, IN, 46202, USA.
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Zimet
keywords: early adolescence; healthcare providers; immunization