Inadequacy of lmmunoglobulin M hepatitis B core antibody in detecting acute hepatitis B virus infection in infants of HBsAg carrier mothers

To study the usefulness of IgM hepatitis B core antibody (anti‐HBc IgM) for detecting hepatitis B virus infections in infants of hepatitis B surface antigen (HBsAg) carrier mothers, serial serum samples from 86 infants of carrier mothers were tested for anti‐HBc IgM with a highly specific enzyme immunoassay. Asymptomatic hepatitis B infection occurred frequently in infants under 12 mo of age. Anti‐HBc IgM never became positive in 25 infants infected under 9 mo old. It was positive in only 1 of 6 infected at 9 mo and 4 of 13 infected at 12 mo of age. The IgM antibody lasted for less than 6 mo. Although the infection was delayed in 28 infants receiving hepatitis B immune globulin, the poor anti‐HBc IgM response did not seem to be due to the immune prophylaxis. Our study clearly indicates the limitation of anti‐HBc IgM for detecting acute hepatitis B infection in infants born to HBsAg carrier mothers.