The data of 178 newborn infants were collected and analyzed retrospectively, who were determined for HBsAg. The positive rate of HBsAg, hepatitis B 5 items, HBsAg concentration and vaccination time after vaccine inducing were determined, and the relationships were analyzed statistically. Interference testing was performed to investigate the influence of serum jaundice in HBsAg assay. The hepatitis B virus vaccine was diluted in vitro according to neonatal blood volume, and HBsAg concentration was detected.

A total of 178 newborn infants were determined for 184 times totally, and 16 newborn infants had positive HBsAg. Of these 16 newborn infants, 11 cases could be attributed to vaccination, 3 cases were due to mother-to-child transmission, and 2 cases were with unknown cause. The HBsAg positivity for newborn infants receiving vaccine 0-7d were statistically significant in comparison with those of 8-14 d and 15-31 d (P=0.046 and 0.032). After the vaccine was injected, the concentration of HBsAg was 0.12 (0.07-0.25) IU/mL, which was at low level. The concentration of HBsAg reached the highest level after 0-2d of injection, and then it decreased gradually. There were totally 11 samples which were HBsAg single positive, and 3 samples of them were both HBsAg and anti-hepatitis B surface antigen antibody (HBsAb) positive, which was obviously different from the common serum pattern of hepatitis B virus infection. HBsAg concentration was 0.13 IU/mL at 1:600 dilution of vaccine, being similar with that of vaccine-induced HBsAg positive [0.12 (0.07-0.25) IU/mL]. Jaundice interference testing showed that 383.9 μmol/L total bilirubin and 29.9 μmol/L direct bilirubin distractors did not affect HBsAg results.

Transient HBsAg positivity can occur in newborn infants within 2 weeks post-vaccination. Newborn infants may not be screened for HBsAg within 2 weeks following vaccination against hepatitis B virus.