OBJECTIVES: Hepatitis-B virus (HBV) infection poses a significant health burden with current guidelines recommending HBV vaccination for high-risk adults. However, there is limited national-level data on the prevalence and trends of vaccine-induced immunity in high-risk US adults. Therefore, this study examined HBV immunization and vaccine-induced immunity in high-risk US adults.

METHODS: This retrospective, cross-sectional study used the National Health and Nutrition Examination Survey (NHANES) from 2013-2020. The study included adults ≥18 years classified as high-risk and non-high-risk populations based on the American Association for Study of Liver Disease & US-Preventive Task Force. These populations included patients with pregnancy, diabetes-mellitus, elevated aspartate-aminotransferase or alanine-aminotransferase, sexually transmitted diseases, illicit drug users, and dialysis. Participants having multiple sexual partners, inmates of correctional facilities, healthcare workers, and persons needing immunosuppressive therapy were not included due to a lack of data. Adults were considered immunized if serological HBV-antibody titer is >10mIU/mL. Trend analysis was used to evaluate prevalence trends of vaccine-induced immunity among high-risk adults across three survey-year cycles. Multivariate logistic regression was used to evaluate the predictors of immunization in high-risk populations based on the conceptual framework of the Anderson Behavioral Model (ABM).

RESULTS: According to 2013-2020, NHANES, an estimated 23.3% (95%CI:23.1%-23.5%) high-risk US non-institutionalized adults had vaccine-induced immunity to HBV, while 27.3% adults (95%CI:26.4%-28.0%) in the non-high-risk group, were vaccinated. The prevalence of vaccine-induced immunity among high-risk adults increased significantly from 22.04% in 2013-2014 (95%CI:21.8-22.3) to 23.89% in 2017-2020 (95%CI:22.8-24.8) (P<0.001). Multivariate analysis found that older-age (OR=0.16, 95%CI:0.13-0.18) female sex (OR=1.2, 95%CI:1.06-1.36), Asian (OR=1.82, 95%CI:1.45-2.29) race and having insurance (OR=1.32, 95%CI:1.14-1.5) were predictors of being immunized for HBV.

CONCLUSIONS: Despite having periodic releases of guidelines for immunization in the high-risk population, the prevalence of vaccine-induced immunity remains low. Concerted efforts are needed to improve the rate of immunization in the high-risk population.