Comparison of enzyme- and radio-immunoassay kits to detect hepatitis B surface antibody response among hepatitis B vaccinees.

A total of 288 of sera was obtained from 96 hepatitis B vaccinees to test antibody to hepatitis B surface antigen (anti-HBs) by enzyme immunoassay (EIA) and radioimmunoassay (RIA), respectively. An anti-HBs titer greater than 10 mIU/mL is required for immunity; 172 (59.7%) were positive by EIA and 173 (60.1%) were positive by RIA. A correlation study of anti-HBs titers tested by these two methods showed a correlation coefficient r = 0.889 (n = 162, p less than 0.001). Of 173 serum specimens whose anti-HBs were positive by RIA, 10 were negative by EIA; those 10 had had anti-HBs titers between 11 to 20 mIU/mL by RIA. Among 172 serum specimens whose anti-HBs were positive by EIA, 9 were negative by RIA; 3 of those were between 21 to 70 mIU/mL, and 6 were between 11 to 20 mIU/mL by EIA. Of the 96 vaccinees, following first dose of hepatitis B vaccination their anti-HBs response rates were found to be 20.8% by EIA and 17.7% by RIA. Following second and third vaccinations, their anti-HBs response rates were 65.6% and 92.7% by EIA, and 71.9% and 90.6% by RIA, respectively. Thus, EIA correlates well with RIA for anti-HBs testing especially when its titers are greater than 70 mIU/ml.