And while the health of most of these people may not be seriously affected, they remain carriers of the virus, able to infect others. For about 20 percent of people infected with hepatitis C, the consequences are more serious. They will develop chronic liver diseases, the leading reason for liver transplants in the United States. Many develop cirrhosis of the liver, which is often fatal. The principal drugs used to treat hepatitis C are all based on interferon, an immune system protein produced by the body to fight viral infections.
Treatment requires injections three times a week for six months to a year.
The NIH panel found that the longer course of treatment seems to be more effective. Perhaps as many as 30 percent of patients could be cured if they stayed on interferon for a year, the panel concluded. Because of the limited efficacy of current treatment, the panel called for limiting use of interferon therapy only to patients who have signs of progressive cirrhosis. Correspondent Eugenia Halsey contributed to this report . The Hepatitis Foundation International External sites are not endorsed by CNN Interactive.