[Vaccination against hepatitis A]

Abstract

Hepatitis A is a worldwide disease transmitted by oral-fecal route, the endemicity level is high in developing countries and in the Far East. In northern Europe the endemicity level is low, but it is intermediate in the European Mediterranean area. Seroepidemiological surveys show that in Italy, as in many other European countries, hepatitis type A endemicity is declining. Therefore, immunity to infection shifts towards the older generations, leaving an increasing number of teenagers and young adults susceptible to the infection. Since in adults the infection is associated with higher levels of morbidity and mortality than in children, hepatitis A remains a public health problem. Moreover, travellers visiting an endemic area are at risk of acquiring the disease. Short-term, passive immunization with immune serum globulins is not a satisfactory method of controlling hepatitis A. The best way of controlling HAV endemicity is vaccination and a satisfactory vaccine will be available by 1993. Soon after HAV propagation in cell culture was achieved, three different approaches to HAV vaccine production were investigated: recombinant vaccines, live attenuated vaccines, inactivated vaccines. The production of a recombinant vaccine is, as yet, unavailable, because two HAV surface proteins linked together in a definite three dimensional configuration are needed to stimulate an effective immune response. A satisfactory live attenuated vaccine has not yet been obtained because of difficulties in maintaining a stable level of attenuation. Consequently, attention has shifted towards inactivated vaccines, and the HM 175 strain inactivated vaccine has been produced and widely studied in over 25,000 human volunteers.(ABSTRACT TRUNCATED AT 250 WORDS)