VACCINATION FOR THE CONTROL OF HEPATITIS-A AND HEPATITIS-B

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-ag ed subjects, highlights an increasing susceptibility to hepatitis A. L ater in the life, HAV infections become more serious and expansive. Co ntrol measures against hepatitis B have nearly stopped HBV spread link ed to blood transfusions and mothers to infants transmission. Now, com mon risk factors are first sexual exposure, then injecting drug use, e specially among young people. Vaccination is recognized as the most ef fective process for prevention. Recombinant hepatitis B vaccines have taken the place of plasma-derived vaccines. Although non responder ind ividuals and escape mutants of HBV may hamper vaccinal coverage, hepat itis vaccines are highly immunogenic in immunocompetent people, allowi ng simplified schedules and reduced HBsAg dosages for children. Inacti vated HAV vaccines now licensed prove to be highly immunogenic after o nly one injection. Hepatitis B vaccination targeted on high risk group s remains imperative but inadequate for reducing hepatitis B occurence . A universal hepatitis B vaccination program in childhood and early a dolescence would nearly stop the spread of HBV in the populations befo re ten years. Likewise, hepatitis A vaccination of travelers to endemi c areas, all individuals exposed to contaminations from fecal sources, and food handlers, could reduce the spread ct HAV in the community bu t would not completely prevent outbreaks of hepatitis A. Advantages of universal immunization of babies are not proved yet. Implementation o f preventive strategies first needs a comprehensive surveillance of vi ral hepatitis in France.