OBJECTIVES: The latest recommendation from CDC suggests that U.S. adults ≥ 50 years receive the herpes zoster (HZ) vaccine. However, recent studies showed very low rates of HZ vaccination, particularly among those under 60 years. This study aimed to identify the factors predicting early HZ vaccination among U.S. adults ≥ 50 years.

METHODS: This retrospective observational study included U.S. adults aged ≥ 50 years between 2014 and 2016 who had ≥ 1 year of continuous enrollment in the IBM Marketscan® commercial claims and Medicare supplemental databases. Select social determinants from multiple publicly-available sources were linked with the Marketscan® data. Pharmacy, inpatient, and outpatient claims were assessed to evaluate HZ vaccination. The vaccinated individuals were categorized into groups of five-year age-increments. Ordinal logistic regression identified predictors of early vaccination.

RESULTS: Between 2014 and 2016, 557,077 individuals were vaccinated against HZ. Odds of HZ vaccination early after 50 years decreased with female gender (OR: 0.845, 95% CI: 0.836-0.853), no flu vaccination (OR: 0.466, 95% CI: 0.461-0.471), more hospital (OR: 0.780, 95% CI: 0.768-0.792), emergency (OR: 0.929, 95% CI: 0.920-0.938), doctor office (OR: 0.998, 95% CI: 0.998-0.999), or pharmacy visits (OR: 0.985, 95% CI: 0.984-0.985), immunocompromised status (OR: 0.704, 95% CI: 0.695-0.713), and increases in percentage of Democratic voters in the MSA (OR: 0.858, 95% CI: 0.802-0.917). Residing in the East North Central or Middle Atlantic divisions compared to the Pacific, West South Central, or West North Central divisions was associated with lower odds of early vaccination. Odds of early vaccination marginally increased with increases in health literacy in the MSA.

CONCLUSIONS: Differences based on geography, political views, and health literacy exist in receiving the HZ vaccine at recommended age. Policy makers and healthcare providers need to emphasize early HZ vaccination for adults aged ≥ 50 years.