INTRODUCTION: Adult vaccination coverage rates in the US are well below national targets, leaving many adults at increased risk. Additionally, typical vaccination coverage calculations do not adequately approximate population immunity as they do not consider whether multidose vaccines were administered within the recommended schedules. As timely administration of each dose optimizes overall vaccine effectiveness, we sought to document adherence to and completion of the hepatitis A (HepA), hepatitis B (HepB), and combined hepatitis A and hepatitis B (HepA-HepB) multidose vaccine schedule in an insured adult population in the US.
METHODS: We conducted a retrospective database study of administrative claims from 2008 to 2015 (analyzed in 2017). Completion of 2 (HepA) and 3 doses (HepB and HepA-HepB), and adherence to the 2- and 3-dose recommended schedules were measured among individuals aged 19 years and older at first dose. The proportion of patients who completed 2 and 3 doses and were adherent to the recommended schedule were estimated using Kaplan-Meier methods.
RESULTS: For HepA, 27.14% of initiating adults were adherent to the recommended schedule, and 32.05% had received a second dose by 42 months. Approximately one-third of adults who initiated the HepB or HepA-HepB series completed all 3 doses within 2 years of the minimum spacing (31.17% and 32.27%, respectively). Generally, completion and adherence were highest in individuals aged 60-64 years at the time of initiation.
CONCLUSIONS: Hepatitis vaccine adherence and completion in adults is suboptimal. As a result, the majority of adults initiating each series may not be receiving the full protective benefit of these multidose vaccines.