Immunization Status and Effectiveness Analysis of Hepatitis B Vaccine Among Preterm Infants in Fujian Province, 2022–2023

Objective: This study evaluated hepatitis B vaccine (HepB) uptake, associated influencing factors, and post-vaccination immune responses among preterm infants residing in Fujian Province. The findings can support targeted improvements in hepatitis B prevention and control strategies tailored for this high-risk neonatal population. Methods: We conducted a multicenter cross-sectional study combined with short-term prospective serological follow-up across five counties, cities and districts of Fujian Province between 2022 and 2023. A total of 779 eligible preterm infants were enrolled in this study. We collected demographic information of participating mothers and infants, as well as complete HepB vaccination records throughout the study period. For 363 enrolled infants, we performed serological tests to detect hepatitis B surface antigen (HBsAg) and hepatitis B surface antibody (HBsAb) at 1–2 months after they completed the full HepB vaccination series. To explore factors linked to timely administration of the first HepB dose (HepB1), completion of the full vaccination course and HBsAb serostatus, we adopted a set of statistical approaches including descriptive statistics, the chi-square test (Fisher’s exact test was used for groups with small sample sizes) and binary logistic regression. Results: The timely HepB1 vaccination rate among all preterm infants was 78.18%, while 63.80% completed the full vaccination schedule as required. In the serology cohort, the HBsAb positive rate was 90.91%, and 8.82% of infants showed double-negative HBsAg and HBsAb results, indicating susceptibility to HBV infection. Multivariate analysis identified multiple risk factors for delayed vaccination. Preterm infants were more likely to receive vaccinations late if their mothers tested HBsAg-negative (HepB1: OR = 25.231, 95%CI: 4.997–127.406; full-course HepB: OR = 2.440, 95%CI: 1.395–4.269), were delivered in county-level or lower-tier medical facilities (HepB1: OR = 3.724, 95%CI: 2.107–6.580), or were born via cesarean section (HepB1: OR = 3.460, 95%CI: 2.169–5.520; full-course HepB: OR = 1.954, 95%CI: 1.411–2.704). Additional risk factors included a gestational age below 34 weeks (HepB1: OR = 4.369, 95%CI: 1.894–10.081; full-course HepB: OR = 2.237, 95%CI: 1.148–4.359) and a birth weight less than 2500 g (HepB1: OR = 2.251, 95%CI: 1.397–3.629; full-course HepB: OR = 1.513, 95%CI: 1.065–2.150). Conclusions: Preterm infants enrolled from five regions in Fujian Province achieved robust immune protection following standard HepB vaccination. However, timely first-dose coverage and on-schedule full-course vaccination remain suboptimal in this cohort. Observed gaps in routine vaccination management at primary care settings highlight a key area for improvement in local hepatitis B prevention. Targeted standardized training for maternity care staff at county-level facilities, paired with a full-cycle follow-up system for preterm infant vaccination, may further strengthen hepatitis B mother-to-child transmission (MTCT) interruption in the study regions.