Up to 5.3 million people-2 percent of the U.S. population-are living with chronic hepatitis B or hepatitis C. These diseases are more common than HIV/ AIDS in the U.S. Yet, because of the asymptomatic nature of chronic hepatitis B and hepatitis C, most people who have them are unaware until they have symptoms of liver cancer or liver disease many years later. Each year about 15,000 people die from liver cancer or liver disease related to hepatitis B and hepatitis C. Hepatitis B and hepatitis C can be either acute or chronic. The acute form is a short-term illness that occurs within the first six months after a person is exposed to hepatitis B virus (HBV) or hepatitis C virus (HCV) which cause hepatitis B and hepatitis C, respectively. The diseases can become chronic, although this does not always happen and, particularly in the case of hepatitis B, the likelihood of this becoming a chronic disease depends on a person's age at the time of infection. Although the number of people with acute hepatitis B is declining in the U.S., mostly because of the availability of hepatitis B vaccines, about 43,000 people still develop acute hepatitis B each year. People at risk for hepatitis B include infants born to women with the disease and those who have sexual contact or share injection drug equipment with a person with the disease. People who received a blood transfusion before 1992 and past or current injection-drug users are at risk for chronic hepatitis C. In 2008, the Institute of Medicine convened a committee to assess current prevention and control activities for hepatitis B and hepatitis C and to determine ways to reduce new cases of HBV and HCV infections and illnesses and deaths from chronic viral hepatitis. The committee concludes that chronic. .. because of the asymptomatic nature of chronic hepatitis B and hepatitis C, most people who have them are unaware until they have symptoms of liver cancer or liver disease many years later. The Institute of Medicine serves as adviser to the nation to improve health. Established in 1970 under the charter of the National Academy of Sciences, the Institute of Medicine provides independent, objective, evidence-based advice to policy makers, health professionals, the private sector, and the public.