• Portion of subjects who have a seroprotective immune response (anti-HBsAg ≥ 10 mIU/ml) after the final active injection in each treatment group (Week 12 for HEPLISAV™ and Week 28 for Engerix-B®) [ Time Frame: 28 weeks ] [ Designated as safety issue: No ]
  

• Rates of adverse events and local and systemic reactions to injections [ Time Frame: 28 weeks ] [ Designated as safety issue: Yes ]
  

Infection with hepatitis B virus (HBV) is a major global health problem. Worldwide, it is estimated that 2 billion people have been infected previously and 350 million are chronically infected. While acute HBV infection is associated with significant illness, the risk of chronic infection is of great importance since 5-10% of infected adults will not clear the infection after the initial phase of the illness. About 25% of people who do not initially clear the infection will later develop chronic active hepatitis.

This study will evaluate the safety and efficacy of two injections of HEPLISAV™, compared with three injections of a commercially available HBV vaccine, Engerix-B®, in subjects 11 to 55 years old. About 1,740 subjects will be included in the study. Once subjects have been consented, screened, and randomized to treatment, all subjects will receive a total of three injections over a 24-week period, with a follow-up visit at 28 weeks. Subjects randomized to Engerix-B® will receive 3 injections of active vaccine, while subjects randomized to HEPLISAV™ will receive 2 injections of active vaccine plus 1 injection of placebo. Safety and tolerability will be evaluated by occurrence of adverse events, periodic laboratory tests, vital signs, and local/systemic reactogenicity.

Comparison: Subjects will receive treatment with either HEPLISAV™ or the comparator vaccine, Engerix-B®.