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-a ged subjects, highlights an increasing susceptibility to hepatitis A. Later in the life, HAV infections become more serious and expansive. C ontrol measures against hepatitis B have nearly stopped HBV spread lin ked to blood transfusions and mothers to infants transmission. Now, co mmon risk factors are first sexual exposure, then injecting drug use, especially among young people. Vaccination is recognized as the most e ffective process for prevention. Recombinant hepatitis B vaccines have taken the place of plasma-derived vaccines. Although non responder in dividuals and escape mutants of HBV may hamper vaccinal coverage, hepa titis vaccines are highly immunogenic in immunocompetent people, allow ing simplified schedules and reduced HBsAg dosages for children. Inact ivated HAV vaccines now licensed prove to be highly immunogenic after only one injection. Hepatitis B vaccination targeted on high risk grou ps remains imperative but inadequate for reducing hepatitis B occurenc e. A universal hepatitis B vaccination program in childhood and early adolescence would nearly stop the spread of HBV in the populations bef ore ten years. Likewise, hepatitis A vaccination of travelers to endem ic areas, all individuals exposed to contaminations from fecal sources , and food handlers, could reduce the spread of HAV in the community b ut would not completely prevent outbreaks of hepatitis A. Advantages o f universal immunization of babies are not proved yet. Implementation of preventive strategies first needs a comprehensive surveillance of v iral hepatitis in France.