HEPATITIS-B - EVOLVING EPIDEMIOLOGY AND IMPLICATIONS FOR CONTROL

Control and the possible elimination of transmission of HBV infection is possible with the appropriate use of hepatitis B vaccines. The prevention of chronic HBV infection has the potential of reducing the association burden of chronic liver disease and primary hepatocellular carcinoma. Worldwide, strategies for the effective use of hepatitis B vaccine have been developed and are being implemented in those areas where childhood transmission is the predominant source of chronic HBV infections. However, in the United States and other areas with ''low'' rates of HBV infection, current vaccination strategies have not been effective and have not fully taken into account the multifaceted epidemiology of HBV infection in those areas. Unfortunately, the majority of infections occur among adults who have been the most difficult to access, who acquire infection before they realize they are at risk, and where the changing epidemiology of HBV infections among the various risk groups only emphasizes the problems of vaccine delivery.(33,78) In addition, the majority of persons receiving vaccine as a result of the current strategy to immunize adult high-risk groups have been persons who acquire HBV infection through occupational exposure, a group that accounted for no more than 5% of cases even before vaccine was introduced. The failure of the current immunization strategy to prevent a disease with significant health care and economic consequences is beginning to cause a reevaluation of this approach.(32,33,85,86) A comprehensive approach to eliminating HBV transmission must address infections acquired during early childhood as well as those acquired by teenagers and adults. The epidemiology of HBV infections in the United States indicates transmission of infection could be eliminated by: (1) universal HBsAg screening of pregnant women with immunoprophylaxis of infants born to potentially infectious mothers to prevent perinatal infections, and (2) the integration of hepatitis B vaccine into current childhood immunization schedules to prevent early childhood infections in high-risk populations and to provide immunity to teenagers and adults prior to becoming at risk of infection. The currently emerging data showing the long-term efficacy of hepatitis B vaccine given to infants and the success of integrating hepatitis B vaccine into childhood immunization schedules(87,88) indicate that control of this most important chronic infection is attainable.