Harvoni is a prescription medication used to treat chronic hepatitis C (genotype 1) in adults. It contains a combination of two drugs, ledipasvir (an HCV NS5A inhibitor) and sofosbuvir (a nucleotide analog inhibitor of HCV NS5B polymerase), and is a fixed dose medication for patients infected with the disease (severe hepatitis C genotype 1--the most prevalent form of infection). Harvoni is prescribed to adults, and is not yet known to be safe and effective for children. Medical studies by CDC indicate that over 3 million people in the US carry the disease. The drugs in Harvoni form a new type of drug known as direct acting antiviral agents whose function is to obstruct the enzymes the hepatitis C virus requires to multiply.