The status of Australia antigen (Au-Ag) and Australia antigen antibody (Au-Ab) was investigated in 27 infants less than 4 months of age with direct reacting hyperbilirubinemia, and in their parents. A diagnosis of viral hepatitis
could be excluded in eight infants; of the remaining 19, ten were positive for Au-Ag and another three had suggestive evidence of hepatitis virus B (HBV) infection.
https://pediatrics.aappublications.org/content/54/2/157