Hepatitis B antigen and prevention of post-transfusion hepatitis B

Screening for hepatitis B antigen (HB-sAg) in the serum of blood donors and exclusion of antigen-positive blood units have reduced the frequency of post-transfusion hepatitis but several cases of hepatitis B still occur in association with transfusions. One explanation for this is probably that HB-sAg is not an indicator of infectivity. Thus healthy carriers of the antigen seem to have low infectivity while carriers with chronic liver disease as well as donors incubating hepatitis B probably present a great risk.