Assessment of human papillomavirus vaccination rates of adolescents in California, 2018-2019

Accurate documentation of state-level human papillomavirus (HPV) vaccination is required for public health planning and to inform corrective actions. To examine the representativeness of the California Immunization Registry, we compared the National Immunization Survey (NIS)-Teen, commercial HMOs in California, Medi-Cal, and California Immunization Registry data for HPV vaccine series completion. Our objectives were to evaluate the vaccine registries, compare and report their completeness, and make recommendations on how to improve and use these studies. Vaccination values were extrapolated for all adolescents aged 13 to 17 years from 2018 to 2019 from NIS-Teen, adolescents aged 13 years from 2018 to 2019 reported in the California Immunization Registry, and adolescents aged 13 years for 2018 for commercial HMOs and Medi-Cal. HPV series completion among 13-year-olds in 2018 for commercial HMOs was 50 %, Medi-Cal was 45 %, and the California Immuni-zation Registry was 28 %, with NIS-Teen rates for 13 to 17-year-olds at 50 % in 2018 and 54 % in 2019. Both rural and urban geographic regions were found to have low completion rates of the HPV series, with trends ranging from 13 % to 45 %. The California Immunization Registry's lower HPV vaccine series completion among 13-year-olds compared to the other reporting sources is most likely due differences in reporting and data collection. Importantly, this data will serve as a comparator for future, similar studies of various sources of HPV vaccination rates following the passing of Bill-1797, which will mandate immunization reporting starting in January 2023.