Prevalence of Undetectable Vaccine‐Induced Immunity Against Hepatitis B Virus in US Adults at High Risk for Infection

In 2015, the Centers for Disease Control and Prevention reported a substantial increase in the number of acute hepatitis B virus (HBV) infections in the United States. Although national guidelines recommend vaccination of adults at high risk for HBV infection, the prevalence of undetectable immunity (i.e., susceptibility) in this population remains unknown. In this study, we analyzed a nationally representative sample using the National Health and Nutrition Examination Survey to evaluate the prevalence, trend, and predictors of undetectable vaccine‐induced antibodies against HBV surface antigen (<10 mIU/mL) among high‐risk adults from 2003‐2014. Among adults at high risk for HBV infection, the prevalence of undetectable immunity decreased from 83.2% in 2003‐2004 (95% confidence interval [CI]: 81.3‐85.0) to 69.4% (about 64 million) in 2013‐2014 (95% CI: 66.0‐72.6). The prevalence decreased significantly in individuals with multiple sex partners or sexually transmitted disease and in pregnant women. However, there were no significant changes in men who have sex with men (MSMs), intravenous drug users (IDUs), hepatitis C virus (HCV)‐infected and patients with diabetes, and those with elevated aspartate aminotransferase/alanine aminotransferase (AST/ALT). Mexican Americans had the highest prevalence of undetectable immunity (77.6%, 95% CI: 72.6‐81.9), followed by non‐Hispanic whites (70.1%, 95% CI: 66.9‐73.1). Older age, lower socioeconomic status, and having at least 1 high‐risk factor were associated with a higher risk of undetectable immunity, whereas an increased risk among the foreign‐born disappeared after multivariable adjustment. Conclusion : Approximately 64 million high‐risk adults in the United States remain susceptible to HBV infection, especially MSMs, IDUs, diabetics, HCV patients, and populations with elevated AST/ALT. To eliminate HBV, efforts should be made to increase screening and vaccination in high‐risk adults.