Vaccines to prevent hepatitis B and hepatitis A virus infections.

Vaccines to prevent hepatitis B infection became available in 1982, and were recommended primarily for adults considered at high risk because of exposure in the workplace or lifestyles that lead to sexual or parenteral exposure to the virus. Plasma-derived and recombinant vaccines produced in yeast are highly immunogenic, safe, and effective for all age groups. Decreased response and protection by vaccine occur in older persons and in persons with immunosuppressive illnesses. The main issues concerning current vaccination programs include the possible use of lower doses to reduce the cost of the vaccine, the duration of protection and need for vaccine booster doses, and the need for postvaccination testing in hospitals. The failure of current vaccination programs to decrease disease incidence, a matter of great concern nationally, can be ascribed to failure to deliver vaccine to the groups at highest risk. More effective strategies for control, including the universal vaccination of infants or adolescents, must now be examined. Newer vaccines that incorporate other viral antigens and that may offer increased efficacy are being developed. Vaccines to prevent hepatitis A--both killed and live attenuated vaccines--are undergoing clinical trials and may become available in the next 5 years.