Changing epidemiology and prevention of hepatitis A virus infection

Hepatitis A virus infection is a world-wide public health problem and commonly found in many developing countries, especially in areas where the infection pattern is changing from hyperendemic to hypoendemic. Due to improvement of living standard, infections during childhood have been deferred towards adulthood. Hepatitis A infection in early childhood is usually subclinical, while symptomatic hepatitis A occurs with increasing age. In Southeast Asia, hepatitis A antibody prevalence had considerably declined among the children and adolescents. These data probably reflect the remarkable improvement of hygienic conditions and of effective health education. An increase in the number of susceptible populations could result in an outbreak and become a problem in the near future, particularly in schools, communities and among high risk groups. Therefore, preventive measures are essential in reducing the infection rate. In addition to personal hygiene, immunoprophylaxis represents another promising measure. The hepatitis A vaccines have proven to be safe and efficacious in several clinical trials and are available in many countries. However, the vaccine is very expensive for those residing in developing countries. If possible, reducing the usage of vaccine to one single dose and thus lowering the price would facilitate the implementation of mass vaccination campaigns and thus contribute to the control and possibly to the eventual eradication of the disease.