Vaccine expression systems and maternal/neonatal factors: Impacts on hepatitis B immunization efficacy in preterm infants

The global rise in preterm infants presents specific challenges for hepatitis B prevention. Although hepatitis B vaccination is recommended, detailed understanding of immunogenicity patterns and influencing factors requires further investigation. We analyzed 699 preterm infants completing the hepatitis B vaccination series to assess immunogenicity via geometric mean concentration (GMC) and seroprotection rate (SPR). The regimen was highly immunogenic, with an overall SPR of 99.43% (GMC: 986.36 mIU/mL) and 95.28% of infants achieving high-level protection (anti-HBs ≥100 mIU/mL). Though SPR was consistently high across subgroups, notable GMC variations emerged: infants with gestational age <28 weeks markedly higher GMC (3,735.59 mIU/mL) than more mature subgroups. Statistically significant GMC differences were noted between immunization protocols, with uniform schedules yielding higher values (1,281.26 mIU/mL) than mixed approaches (691.91 mIU/mL; <i>P</i> < .001). Preterm infants of HBsAg-positive mothers maintained a high SPR (96.55%) despite a lower GMC (572.18 mIU/mL). This study confirms that hepatitis B vaccination induces a robust immune response at 1 to 2 months post-vaccination in preterm infants. Observed variations in antibody response magnitude related to vaccine expression system may inform optimization of initial vaccination strategies for preterm populations.