Association of BNT162b2 SARS-CoV-2 vaccination during pregnancy with postnatal outcomes in premature infants.

Objective: The effect of COVID-19 vaccine given during pregnancy on premature infants is unknown. This study aims to determine the association between maternal COVID-19 vaccine with postnatal outcome in premature infants.

Methods: This is a single-centre retrospective case-control study of infants born before 35 weeks gestation to mothers who received SARS-CoV-2 vaccine during pregnancy compared with infant born to non-vaccinated mothers.

Results: A total of 78 infants in each group were included. Infants in the vaccinated group had less respiratory distress syndrome (RDS) (p = 0.02) and less need for respiratory support (p = 0.002), and maternal vaccine had a protective effect on RDS [adjustable OR 0.38 (0.17-0.85)]. Vaccination during the first compared to the second trimester was associated with earlier gestational age (32.3 ± 2.1 vs. 33.3 ± 1.1 weeks, p = 0.03).

Conclusions: We demonstrated that maternal SARS-CoV-2 vaccine is not associated with postnatal adverse effect in premature infants and potentially has a protective effect on RDS. Earlier gestational age among the infants born to mothers who received COVID-19 vaccine during the first trimester did not translate to higher rate of postnatal complications. These findings might suggest that COVID-19 vaccine is safe in high-risk pregnancies, but timing of administration should be considered. Further studies are needed to confirm our findings and the biological mechanism.