Adherence to the HPV Vaccine Dosing Intervals and Factors Associated With Completion of 3 Doses

Abstract

OBJECTIVE: The objectives of this study were to determine (1) adherence to the immunization schedule for the human papillomavirus quadrivalent vaccine and (2) factors associated with completion of the 3-dose series. METHODS: This was a retrospective review of health information records from an academic medical center. The sample included all 9- to 26-year-old female patients who initiated vaccination within 2 years after quadrivalent vaccine availability. Multivariable logistic regression models were estimated to determine associations with completion of the 3-dose series within 7 and 12 months. RESULTS: Among the 3297 female patients who initiated vaccination with human papillomavirus quadrivalent vaccine, 67% self-identified as black and 29% self-identified as white. Fewer than 3% of vaccine doses were received earlier than recommended, but >50% of doses were received late. Completion rates were 14% by 7 months and 28% by 12 months. Independent predictors of completion by 7 months included white versus black race (odds ratio [OR]: 2.04 [95% confidence interval (CI): 1.64–2.56]; P < .001), use of contraception that required intramuscular injections every 3 months (OR: 1.53 [95% CI: 1.12–1.95]; P < .001), and private versus public insurance (OR: 1.31 [95% CI: 1.06–1.63]; P < .05). Age and clinic type were not independent predictors of completion. CONCLUSIONS: Adherence to recommended intervals and completion of the vaccine series were low. Lower rates of completion in black patients compared with white patients raises concern that disparities in vaccine completion could exacerbate existing disparities in cervical cancer.