Infants born to mothers with chronic hepatitis B are recommended to have serological testing 3–12 months after they complete the infant hepatitis B vaccine course

It is recommended that levels of hepatitis B surface antigen (HBsAg) and antibody to HBsAg (anti-HBs) in infants born to mothers with chronic hepatitis B are measured 3–12 months after they complete the infant vaccine course. Do not test the infant before 9 months of age, to avoid detecting anti-HBs from the hepatitis B immunoglobulin given at birth. See Infants born to mothers who are hepatitis B surface antigen–positive are recommended to receive both hepatitis B vaccine and HBIG. See Laboratory diagnosis.