Maternal-infant transfer of SARS-CoV-2 antibodies following vaccination in pregnancy: A prospective cohort study.

To measure and evaluate the impact of receiving severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines in pregnancy on immunoglobulin G (IgG) and immunoglobulin A (IgA) titres in maternal and infant samples. Prospective cohort study. Tertiary obstetric centre. 52 pregnant women who received one or more SARS-CoV-2 vaccine doses during pregnancy and their neonates. IgG and IgA concentrations against SARS-CoV-2 antigens were measured from samples collected at delivery and 4–6 weeks postpartum and compared using Spearman correlations. Maternal and infant IgG and IgA titres in response to vaccination and infection in pregnancy. In maternal serum collected at delivery, participants without evidence of prior infection who received 3 + doses of a SARS-CoV-2 vaccine had higher Anti-Spike (S) IgG geometric mean concentrations (log 10 AU/mL)(GMC) than those who received 2 doses (3 + Doses = 5.00, 2 Doses = 4.60, p = 0.08). The differences in IgG Anti-S GMC were statistically significant in cord serum, and in postpartum samples of maternal serum, infant serum and breast milk (Cord GMCs: 3 + Doses = 5.32, 2 Doses = 4.98, p < 0.05; Postpartum maternal serum GMCs: 3 + Doses = 5.25, 2 Doses = 4.57, p < 0.001; Postpartum infant serum GMCs: 3 + Doses = 5.10, 2 Doses = 4.72, p = 0.03; Postpartum breast milk GMCs: 3 + Doses = 2.61, 2 Doses = 1.94, p < 0.0001). Among participants with 3 + Doses, those with evidence of SARS-CoV-2 infection had statistically significant higher anti-S IgG GMCs than those without prior infection (Maternal serum at delivery: SARS-CoV-2+=5.65, SARS-CoV-2-=5.00, p = 0.004; Cord: SARS-CoV-2+=5.68, SARS-CoV-2-=5.32, p = 0.02; Postpartum maternal serum: SARS-CoV-2+=5.66, SARS-CoV-2-=5.25, p < 0.001; postpartum infant serum: SARS-CoV-2+=5.50, SARS-CoV-2-=5.10, p = 0.003; Postpartum breast milk: SARS-COV-2+=3.25, SARS-COV-2-=2.61, p = 0.009). Significant positive correlations were found for anti-S IgG titres between paired maternal and infant samples at delivery and postpartum (Delivery: R = 0.91, p < 0.001; postpartum: R = 0.86, p < 0.001). Receipt of a SARS-CoV-2 vaccine and SARS-CoV-2 infection elicit strong IgG and IgA antibody responses in pregnant women with evidence of transplacental transfer to the fetus. [ABSTRACT FROM AUTHOR]