[Transmission of viruses (from A to E) and prevention].

Recent advances in epidemiology, virology and molecular biology have made it possible: 1) to isolate and characterize the hepatitis C and D viruses (and soon the virus of hepatitis E); 2) to develop vaccines against hepatitis A and recombinant vaccines against hepatitis B; and 3) to obtain a better understanding of the modes of transmission of the viruses and, consequently, to devise and offer an efficient prophylaxis.