Objective To determine the prevalence of hepatitis B surface antigens (HBsAg) and hepatitis B surface antibodies (anti-HBs) in 1-12 years-old children in Mianyang city, Sichuan Province. Methods Children born after the implementation of Hepatitis B immunization policy were selected using a stratified random cluster sampling strategy from January to December 2015. A total of 72 623 eligible children participated in the study, which included a questionnaire survey and blood tests (0.3 mL vein blood) for HBsAg and anti-HBs with ELISA method. Repeated tests were performed on the blood samples with a HBsAg positive result. Results About 0.24% of the children were HBsAg positive; 64.50% were anti-HBs positive; 35.26% were both HBsAg and anti-HBs negative. The standardized rates based on the 2010 population census were: 0.24% HBsAg positive, 64.05% anti-HBs positive, and 35.71% both HBsAg and anti-HBs negative. HBsAg positive rates increased with age, ranging from 0% to 0.65% (PPPPPPP
