The A's and B's of vaccine-preventable hepatitis: improving prevention in high-risk adults.

Acute hepatitis A and acute hepatitis B are associated with significant morbidity, time away from work or usual activities, substantial cost to the healthcare system, and some mortality. Despite the availability of vaccines against hepatitis B and hepatitis A since 1981 and 1995, respectively, and a combined hepatitis A and B vaccine since 2001, immunization rates against these vaccine-preventable diseases are appallingly low. In particular, several groups of adults, such as men who have sex with men, heterosexuals with multiple partners, injection drug users, persons with human immunodeficiency virus infection, travelers to endemic areas, and persons with chronic liver disease, are at particularly high risk for acute hepatitis A and B or for a more severe illness or a higher rate of chronicity in the case of hepatitis B. Studies have confirmed that hepatitis A and hepatitis B vaccines are safe and immunogenic in patients in these populations, although patients with more advanced disease may respond less well. These observations have led to the recommendation that patients falling into the above risk groups undergo hepatitis A and B vaccination early in the natural history of their underlying risk behavior or diseases. Vaccination rates are low in clinical practice, and public health and educational programs are needed to overcome barriers to facilitate timely implementation of these recommendations. The use of a combined vaccination, possibly using an accelerated administration schedule, provides convenience and may increase compliance.