Paediatricsmiddle twist
A boy was born at term to a woman with chronic hepatitis B infection. He was given hepatitis B immunoglobulin and monovalent hepatitis B vaccine within twelve hours of birth, and has now had the hepatitis B containing vaccine at two, four and six months of age. He is thriving and has been breastfed throughout. His mother wants to know when they will find out whether he has been infected. Testing for hepatitis B surface antigen and surface antibody is best performed at which one of the following times?