Inguva S, Barnard M, Ward LM, et al. - Utilizing 2013–2018 Mississippi Medicaid administrative claims data, researchers investigated the factors related to Human Papillomavirus (HPV) vaccine series completion in vaccine initiators in Mississippi Medicaid. They evaluated female as well as male beneficiaries aged 9 to 26 years who started HPV vaccination in the identification period, to determine completion of age-appropriate number of recommended doses within a span of 12 months. In females and males, the estimated vaccine series completion rate was 34% and 30%, respectively. In both genders, vaccine series completion was significantly predicted by younger age at initiation. Particularly, greater odds of completion were seen in initiators in age groups 9 to 10 and 11 to 12 years, respectively, while lower odds of completion were seen in initiators aged 15 to 26 years, relative to initiators aged 13 to 14 years. Lower odds of completion were reported in female as well as male beneficiaries in managed care plans (vs fee-for-service) and of African American race (vs Caucasians). The completion rates were highest among female and male beneficiaries who started HPV vaccine series with a pediatrician. Overall, findings revealed suboptimal HPV vaccination series completion rate in Mississippi Medicaid, although HPV-associated cancer incidence was high in the state. Many sociodemographic factors impact HPV vaccine series completion. To promote the completion of recommended doses, robust education and public health programs are required.