Illustration of the US physician and virologist Harvey Alter (born 1935). Alter is best known for his work on the viruses that cause hepatitis. His work contributed to the isolation and discovery of the Hepatitis C virus, a virus that is spread through blood contact, blood transfusions and sharing of infected needles. This discovery led to the introduction of blood screening programs to prevent transfusion-transmitted hepatitis. Alter was awarded a share of the 2020 Nobel Prize in Physiology or Medicine along with Michael Houghton and Charles M. Rice for his work on the hepatitis C virus.