Influencing factors and necessity of post-vaccination serologic testing follow-up for HBsAg-positive mothers and their infants: A 5-year prospective study in Zhejiang Province, China (2016-2020)

In 2016, China officially proposed for the first time that infants born to HBsAg-positive mothers should be tested for HBsAg and anti-HBs 1-2 months after their third dose of HepB, also known as the post-vaccination serological testing programme. This study aimed to systematically evaluate the implementation and influencing factors of PVST to further reduce HBV infection risk in infants and improve the protective effect of HepB to the greatest extent. A prospective observational study was conducted to investigate the interruption of MTCT of hepatitis B. Univariate and multivariate analyses were applied to explore factors associated with the PVST follow-up rate among HBsAg-positive mothers and their infants. Additionally, bivariate analysis was performed on HBsAg and anti-HBs results in infants born to HBsAg-positive mothers. Here, the participation rate of PVST was 67.08% among 2120 pairs of positive mothers and infants. The HBsAg-positive rate among participants was 0.77%, whereas the anti-HBs positive rate was 96.84%, and both negative rates were 2.39%. Among infants with double negative results (34), only 15 completed three doses of HepB and PVST again, and 14 (93.33%) of which the antibody test results turned positive. Older mothers with high educational levels who reside in the local area were the most likely to PVST follow-up. The PVST programme is necessary to evaluate the HepB response status of newborns after vaccination. Moreover, revaccination for susceptible infants can effectively improve the MTCT-blocking rate of hepatitis B. Therefore, the scope of PVST projects in Zhejiang and China should be expanded.