Quadrivalent Human Papillomavirus Vaccine Initiation in Boys Before and Since Routine Use: Southern California, 2009-2013.

ABSTRACT

OBJECTIVES: We examined the trends and correlates of quadrivalent human papillomavirus vaccine (HPV4) initiation in insured boys during the periods before and after routine use recommendation. METHODS: We grouped data from electronic medical records of boys aged 9 to 17 years from the Kaiser Permanente Southern California prepaid health plan into 3 open cohorts permissive use 2009 to 2010; anal cancer indication added 2010 to 2011; and routine use 2011 to 2013. We estimated adjusted risk ratios (ARRs) between demographics and vaccination initiation using Poisson regression. RESULTS: HPV4 initiation increased across cohorts--1.6%, 3.4%, and 18.5%--with the greatest increase among boys aged 11 to 12 years in cohort 3. Initiation was associated with receiving influenza vaccination in the previous year in all cohorts (cohort 3 ARR = 1.48; 95% confidence interval [CI] = 1.46, 1.51) and with non-White race/ethnicity following routine recommendation (cohort 3, non-Hispanic Black ARR = 1.18; 95% CI = 1.08, 1.30; Hispanic ARR = 1.23; 95% CI = 1.17, 1.29; Asian/Pacific Islanders ARR = 1.16; 95% CI = 1.11, 1.20). CONCLUSIONS: Routine use recommendation increased the uptake of HPV4 in boys. System-level interventions to encourage providers to routinely recommend HPV4 vaccination may help increase HPV4 uptake in boys.