Hepatitis-associated markers in the American Red Cross blood donor population. V. Prevalence of antibodies to core antigen in three blood services regions.

A total of 20,643 samples of blood donated to three American Red Cross Blood Service regions were tested for antibodies to hepatitis B core antigen (anti-HBc) in order to evaluate and understand its significance and implications. All 20,643 samples were non-reactive for hepatitis B surface antigen (HBsAg) when screened at the regions. Overall, 2.2% of all samples were found to have anti-HBc, and a total of 16 had anti-HBc in the absence of antibodies to surface antigen (anti-HBs) activity. 1 of the 16 samples with anti-HBc in the absence of anti-HBs was found to have HBsAg when tested by a sensitive procedural modification of the Austria II test. Samples with low levels of anti-HBc activity were significantly more likely to be negative for anti-HBs.