Influencing factors for low response to hepatitis B vaccination in neonates

Objective To investigate the influencing factors for low response to hepatitis B (Hep B) vaccination in neonates born to HBs Ag-positive mothers. Methods A total of 1152 neonates born to HBs Ag-positive mothers who participated in the project of prevention of mother-to-child transmission of HBV from July 2012 to July 2015 were enrolled. After 96 neonates were excluded, 1056 neonates were included in the final analysis, including 714 neonates born to HBs Ag-positive/HBe Ag-negative mothers and 342 neonates born to HBs Ag-positive/HBe Ag-positive mothers. These two groups of neonates were given immunization at different doses, i. e., 10 μg or 20 μg Hep B derived in Saccharomyces cerevisiae and 100 IU hepatitis B immunoglobulin within 2 hours after birth, followed by the injection of 10 μg or20 μg Hep B at the ages of 1 and 6 months. Venous blood samples were collected at one month after the last immunization to measure the levels of HBs Ag and anti-HBs. The neonates with anti-HBs < 100 m IU/ml were classified as low responders, and those with anti-HBs ≥100 m IU/ml were classified as high responders. The two-independent-samples t test was used for comparison of continuous data between groups, and the chi-square test or the Fisher's exact test was used for comparison of categorical data between groups. An unconditional logistic regression analysis was used to identify the influencing factors for low response to Hep B in neonates. An analysis of covariance was used for comparison of the level of anti-HBs between groups. Results Compared with the 20 μg group, the 10 μg group had a significantly higher rate of low response (5. 7% vs 2. 0%, χ2= 7. 278, P = 0. 007) , significantly lower maternal HBV DNA load [ (2. 90 ± 1. 50) log10 IU/ml vs (7. 73 ± 1. 07) log10 IU/ml, t =-50. 297, P < 0. 001) ]and proportion of the mothers who received antiviral therapy during pregnancy (0. 7% vs 7. 0%, χ2= 34. 552, P < 0. 001) , and a significantly higher rate of preterm birth (3. 2% vs 1. 2%, χ2= 3. 907, P =0. 048) . The 10 μg group had a significantly lower proportion of neonates with artificial feeding than the 20 μg group (37. 8% vs 66. 4%, χ2= 75. 703, P < 0. 001) . In the 10 μg group, the unconditional logistic regression analysis showed that preterm birth (odds ratio [OR]=3. 31, 95% confidence interval [CI]: 1. 05-10. 40, P < 0. 05) and artificial feeding (OR = 2. 67, 95% CI: 1. 38-5. 07, P < 0. 05) were independent risk factors for low response to Hep B vaccination. The analysis of covariance showed that compared with the full-term infants, the preterm infants had a significantly lower level of anti-HBs (P = 0. 004) ; compared with those given breastfeeding or mixed feeding, the neonates given artificial feeding had a significantly lower level of anti-HBs (P = 0. 001) . In the 20 μg group, no maternal factors or infantile factors were found to be associated with the response to Hep B vaccination (all P > 0. 05) . Conclusion Preterm birth and artificial feeding are risk factors for low response to Hep B vaccination in neonates. Identification of neonates at risk of low response to Hep B vaccination will provide a basis for developing individualized Hep B vaccination schemes.