Hepatitis B Vaccine in Seniors

The first purpose of this study is to test the body\'s protective reaction (making antibodies) to a licensed hepatitis B vaccine (Recombivax-HB) after it is injected either in the arm fat or muscle. Hepatitis B virus is an important cause of liver disease in humans. More than 21% of healthy adults over age 60 years demonstrate evidence of previous Hepatitis B infection using a common blood test. The second purpose of this study is to learn more information about other reasons (such as body fat content, gene types, etc.), why older people respond less well than younger people to vaccines. The Investigators will also learn more about the ability of certain white blood cells, called T cells, to respond to protein signals in the blood. T cells do not seem to respond as well to these protein signals as individuals age. The Investigators will compare results to a younger group of volunteers who have also been vaccinated with hepatitis B vaccine.