In the US, adult immunization coverage remains low, especially among vulnerable populations, as recent hepatitis A outbreaks have demonstrated. We studied the vaccination history variation among the US adults who use drugs by implementing a community-engaged research survey to identify reported immunization coverage, missed opportunities (MO), and places where immunizations might be delivered. Our analysis of a sample of 1127 participants recruited at community syringe exchanges in three cities identified higher overall vaccination receipt in Los Angeles compared to Atlanta or Las Vegas (e.g., HAV receipt 52.2% LA, 42.1% LV, 41.4% Atlanta). Overall, fewer participants reported having received HAV (45.9%), HBV (47.5%), or influenza (47.6%) vaccines than MMR (57.1%) or Td/Tdap (61.1%). Across sites, HAV receipt was higher for participants incarcerated ≥ 5 years (54.2% vs. 43.6% for those incarcerated < 5 years, 49.4% no incarceration history, p = 0.02). HBV receipt was higher among participants who were not intravenous drug users (56.1% vs. 46.0%, p = 0.03). Additionally, income >$20k predicted higher rates of MMR receipt (67.0% vs. 56.5%, p = 0.009), as did stable housing (62.8% vs. 54.3%, p = 0.01). To address the need to expand vaccine coverage among vulnerable adults, delivering vaccine at sites where persons who use drugs access services, or in correctional facilities, may be warranted.
Keywords: adult vaccination; health equity; hidden populations; immunization; opioid crisis; social determinants; substance use; vaccine coverage; vaccine missed opportunities; vaccine uptake.