CDC recommends that U.S. adults ≥50 years receive the herpes zoster (HZ) vaccine; but few are vaccinated at the recommended age. Little is known about how social determinants of health (SDH) influence timely vaccination. This retrospective observational study included U.S. adults aged ≥50 years who were vaccinated against HZ between 2014 and 2016 from IBM MarketScan commercial claims and Medicare supplemental databases. The cohort was classified into three groups based on age of vaccination: earlier (50-59 years), timely (60-64 years), and later (65+ years). Select SDH data from publicly-available sources were linked and included in multinomial logistic regression assessing the impact of SDH on timely vaccination. The final cohort comprised 549,544 individuals, 49.5% of whom were vaccinated at the age of 60-64. Odds of later HZ vaccination increased with higher poverty (OR: 1.035, 95% CI: 1.031-1.038), more democratic voters (OR: 1.011, 95% CI: 1.010-1.012), and lack of Internet access (OR: 1.028, 95% CI: 1.024-1.032), but decreased with higher health literacy (OR: 0.971, 95% CI: 0.970-0.973). Conversely, higher health literacy and lower poverty were associated with higher odds of earlier vaccination. Being male, not receiving a seasonal influenza vaccine, and higher healthcare utilization were associated with later vaccination. Individuals on an EPO/PPO vs. HMO plan, or who resided in regions other than the Northeast were more likely to receive the vaccine earlier. This study demonstrates the influence of SDH on time of HZ vaccination, but further research is needed to fully understand the impact of SDH on vaccination.
Keywords: Adult vaccination; herpes zoster; preventive medicine; social determinants; vaccine hesitancy.