Determination of hepatitis A antibody response to vaccination by an enzyme immunoassay.

The quantitative responses to vaccination with hepatitis A vaccine was determined in 113 volunteers using a commercially available enzyme-linked immunosorbent assay for total antibodies to hepatitis A. Administration of vaccine or control preparation was carried out according to two regimens; at 0, 1 and 12 months (regimen I) and at 0, 0.5 and 12 months (regimen II). Seroconversion rates (concentrations of HAV antibodies > 50 IU/l) were between 94 and 97% at month 1 for regimen I and regimen II, respectively. The geometric mean titres (GMTs) fell gradually by month 12, and increased rapidly 10-100 fold 1 month after the booster dose at month 12. The GMTs of the groups receiving the control preparation remained below 50 IU/l. No significant differences were found between the antibody responses after regimen I or regimen II. It is concluded that the antibody test (Hepanostika HAV Antibody) can be used safely and adequately for quantitation of responses to hepatitis A immunisation.