EXPERIENCE, PRESENT AND FUTURE RECOMMENDA TIONS FOR THE VACCINE AGAINST HEPATITIS-A

Four years after coming on the market, the first available vaccine aga inst Hepatitis A has revealed an immunogenicity allowing one to forese e 20 years of protection and an innocuity making possible the vaccinat ion of children as young as 1 year old. Over 100 000 members of the Fr ench military have been vaccinated since 1994. This measure is in agre ement with present national recommendations concerning non immune adul ts about to sojourn in endemic regions, individuals who are exposed to risks of contamination in their profession (personnel of day-nurserie s, of boarding establishments and services for handicapped children an d youth, and of treatment of used water), young people who live in boa rding institutions and persons exposed to particular risks (hemophilia cs, polytransfused patients, intravenous drug addicts, homosexuals). O ther targets can be identified as potential transmitters, for example, cafeteria employees and health personnel. In the case of children, a solid natural immunization, acquired by benign infection, if not asymp tomatic, has seemed up to now preferable to a vaccination for which th e efficacy and tolerance had been only partially documented. The strat egy of vaccination should be defined according to the epidemiological context, available means and public health objectives. In a country of high VHA endemicity, collective immunity developed from childhood ren ders all vaccination programs useless in the absence of drinking water and sanitation. As development progresses, the growing receptivity of populations to VHA infection encourages priority vaccination of those individuals most exposed, which does not however prevent a more or le ss occult circulation of the virus. In France, there are an estimated 25 000 cases of symptomatic hepatitis A per year. They are sporadic ca ses or limited epidemic centers in communities, such as day-nurseries, schools, or summer camps. To decrease the incidence of hepatitis A fo r highly exposed groups or the general population would be a more ambi tious objective, requiring preliminary studies : surveys of seropreval ence, investigation of each new epidemic center identification of indi viduals likely to spread the virus. A maximalist strategy seeking to e radicate hepatitis A could also be envisaged; such a strategy would co mprise generalized vaccination of young children, before the age of co llective activities, followed by boosters every 10 to 20 years.