New Hepatitis A and B Vaccines: Summary of a Specialty Session

Five virus species called hepatitis A, B, C, D, and E have been identified as the causative agents of viral hepatitis. All these viruses are antigenically distinct except hepatitis B virus (HBV) and hepatitis D virus (HDV) which share a common hepatitis B surface antigen (HBsAg) envelope. Noninfectious HBsAg particles 22 nm in diameter abundantly contained in plasma of HBV carriers have been used for many years in the preparation of hepatitis B vaccine. Later large-scale production of the same antigen particles by recombinant DNA techniques were employed in the preparation of the vaccine. Both types of hepatitis B vaccines, plasma-derived and recombinant, have been proven to be equally well tolerated clinically and are equally useful in the prevention of HBV and HDV infections. So far, only hepatitis A (HAV) has been grown in cell culture systems. Inactivated hepatitis A vaccines consisted of virus particles propagated in cell cultures which are well-tolerated clinically and useful in the prevention of HAV infection as reported elsewhere in this proceeding.