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ObjectiveWe aimed to assess the impact of early versus late third trimester maternal SARS-CoV-2 vaccination on transplacental transfer and neonatal levels of SARS-CoV-2 antibodies. MethodsMaternal and cord blood sera were collected following term delivery after antenatal SARS-CoV-2 BNT162b2 mRNA vaccination, with the first vaccine dose administered during 27-36 weeks gestation. SARS-CoV-2 spike protein (S) and receptor binding domain (RBD)- specific, IgG levels and neutralizing potency were evaluated in maternal and cord blood samples. ResultsThe study cohort consisted of 171 parturients (median age, 31 years; median gestational age, 39.7 weeks): 83 (48.5%) immunized at early 3rd trimester (1st dose at 27-31 weeks), and 88 (51.5%) immunized at late 3rd trimester (1st dose at 32-36 weeks). All mother-infant paired sera were positive for anti S- and anti-RBD-specific IgG. Anti-RBD-specific IgG concentrations in neonatal sera were higher following early versus late 3rd trimester vaccination and were positively correlated with increasing time since vaccination (r={square}0.26; P=0.001). The median placental transfer ratios of anti-S and anti-RBD specific IgG were increased following early versus late 3rd trimester immunization (anti-S ratio:1.3 vs. 0.9, anti-RBD-specific ratio:2.3 vs. 0.7, P<0.001). Neutralizing antibodies placental transfer ratio was greater following early versus late 3rd trimester immunization (1.9 vs. 0.8, P<0.001), and was positively associated with longer duration from vaccination (r={square}0.77; P<0.001). ConclusionsEarly- as compared to late third trimester maternal SARS-CoV-2 immunization enhanced transplacental antibody transfer and increased neonatal neutralizing antibody levels. Our findings highlight that vaccination of pregnant women early in the third trimester may optimize neonatal seroprotection.
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BackgroundSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during pregnancy and early infancy can result in severe disease. Evaluating the serologic response after maternal vaccination during pregnancy and subsequent transplacental antibody transfer has important implications for maternal care and vaccination strategies. ObjectiveTo assess maternal and neonatal SARS-CoV-2 antibody levels after antenatal mRNA vaccination. Design, Setting, and ParticipantsThis study took place at Hadassah Medical Center in Jerusalem, Israel in February 2021. Maternal and cord blood sera were collected for antibody measurement from mother/newborn dyads following antenatal vaccination. ExposureSARS-CoV-2 BNT162b2 mRNA vaccination. Main outcome and measuresSpike protein (S) and receptor binding domain (RBD) - specific, IgG levels were evaluated in maternal and cord blood sera. ResultsThe study cohort consisted of 20 parturients, with a median maternal age of 32 y ears and a median gestational age of 393/7 weeks at the time of delivery. The median time lapsed from the first and second doses of vaccine administration until delivery was 33 [IQR 30-37] and 11 [IQR 9-15] days, respectively. Of the 20 dyads, all women an d infants were positive for anti S- and anti-RBD-specific IgG. Anti-S and anti-RBD-specific IgG levels in maternal sera were positively correlated to their respective concentrations in cord blood ({rho}s= 0.72; P<0.001 and {rho}s= 0.72; P <0.001, respectively). Anti-S and anti-RBD-specific IgG titers in cord blood were directly correlated with time lapsed since the administration of the first vaccine dose ({rho}s= 0.71; P =0.001 and {rho}s= 0.63; P=0.004, respectively). Conclusion and RelevanceIn this study, SARS-CoV-2 mRNA vaccine administered during pregnancy induced adequate maternal serologic response with subsequent efficient transplacental transfer. Our findings highlight that vaccination of pregnant women may provide maternal and neonatal protection from SARS-CoV-2 infection.
