Mayo Clinic: Four million people in the U.S., 100 million worldwide, are infected with Hepatitis C. It's a virus you can get from blood transfusions given before 1990, shared needles, unclean tattoo needles and sometimes sex.

In many cases it leads to cirrhosis of the liver and eventually liver cancer. Standard treatment with interferon and ribavirin only cures about 45% of all patients. But thanks to two new medications, up to 70% of people with hepatitis C may be be cured. More than 40 medications are in development.