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.