Hope King, et al. - As prevention of hepatitis B virus (HBV) infection can be achieved through vaccination, researchers examined the prevalence and trends in protective levels of hepatitis B surface antibody (anti-HBs) from 2003 to 2014. In addition, they investigated factors linked with protection among adults at high risk. From the 2003–2014 National Health and Nutrition Examination surveys, they retrieved data of adults aged 18-49 years who were tested for HBV and reported at least 1 of the following infection risks: history of sexually transmitted disease, sex with men (for men), infection with human immunodeficiency virus, and injection drug use. Positive anti-HBs serology was reported in 23.4%. Increase in prevalence was observed from 2003–2006 (16.3%) to 2007–2010 (27.3%), but there was no change from 2007–2010 (27.3%) to 2011–2014 (28.1%). This indicates that protective antibodies ≥ 10 mIU/mL were evident in less than one-third of adults aged 18-49 years at risk of infection by 2014. Young age and higher education were the factors predictive of positive anti-HBs serology.