Serum level of anti-hepatitis B surface antigen 6-8 years after hepatitis B vaccination at birth

The duration of protection after hepatitis B vaccination in children is unknown. We determined the serum level of antibody to hepatitis B surface antigen [anti-HBsAg] in 273 randomly selected 7-9-year-old schoolchildren from Zanjan City, Islamic Republic of Iran, who had been fully vaccinated against hepatitis B starting at birth. Titres