[Prevention of hepatitis A and hepatitis B by vaccination].

Abstract

In spite of low endemic levels in France, hepatitis A and hepatitis B remain major concerns for public health. Seroprevalence of antibodies against hepatitis A (anti-HAV), declining below 15% in the 20 years-aged subjects, highlights an increasing susceptibility to hepatitis A. Later in the life, HAV infections become more serious and expansive. Control measures against hepatitis B have nearly stopped HBV spread linked to blood transfusions and mothers to infants transmission. Now, common risk factors are first sexual exposure, then injecting drug use, especially among young people. Vaccination is recognized as the most effective process for prevention. Recombinant hepatitis B vaccines have taken the place of plasma-derived vaccines. Although non responder individuals and escape mutants of HBV may hamper vaccinal coverage, hepatitis vaccines are highly immunogenic in immunocompetent people, allowing simplified schedules and reduced HBsAg dosages for children. Inactivated HAV vaccines now licensed prove to be highly immunogenic after only one injection. Hepatitis B vaccination targeted on high risk groups remains imperative but inadequate for reducing hepatitis B occurrence. A universal hepatitis B vaccination program in childhood and early adolescence would nearly stop the spread of HBV in the populations before ten years. Likewise, hepatitis A vaccination of travelers to endemic areas, all individuals exposed to contaminations from fecal sources, and food handlers, could reduce the spread of HAV in the community but would not completely prevent outbreaks of hepatitis A. Advantages of universal immunization of babies are not proved yet. Implementation of preventive strategies first needs a comprehensive surveillance of viral hepatitis in France.