HPV vaccine initiation at 9 or 10 years of age and better series completion by age 13 among privately and publicly insured children in the US.

The US Advisory Committee on Immunization Practice recommends routine human papillomavirus (HPV) vaccination at 11-12 years of age, but states that vaccination may be initiated as early as 9 years. Our primary goal was to assess whether initiating HPV vaccination at 9-10 years of age, compared to 11-12, was associated with a higher rate of series completion by 13 years of age, and to identify factors associated with series completion by age 13. The study used vaccine claims and other data from the IBM MarketScan Commercial Claims and Encounters (privately insured) and IBM MarketScan Multi-State Medicaid (publicly insured) databases. Participants were 9-12 years of age and initiated HPV vaccination between January 2006 and December 2018 (publicly insured) or February 2019 (privately insured). Among 100,117 privately insured individuals, those initiating the HPV vaccination series at 9-10 years of age had a significantly higher series completion rate by 13 years of age than did those initiating at 11-12 years of age (76.2% versus 48.1%;  < .001). The same pattern was observed for 115,863 publicly insured individuals (70.4% versus 40.0%;  < .001). Provider and health care plan type, female sex, race/ethnicity, and wellness checks or non-HPV vaccinations during the baseline period were significantly associated with series completion by 13 years of age. Proactive initiation of HPV vaccination at 9-10 years of age was associated with higher rates of series completion by 13 years of age. These findings can inform provider education and other interventions to encourage timely HPV vaccination series completion.