HCV infection occurs mainly from contaminated blood or blood products. Using illegal injectable drugs, sharing needles, and unsafe blood transfusions are major causes of infection. More rarely, HCV can also be acquired from sexual and household contacts. Very many people were infected between the 1930s and the 1970s, due to unsafe injection use in many countries, including places in southern and eastern Europe. The most frequent way of HCV infection today is from injection of illegal drugs.