The Effect of Gestational Age at BNT162b2 mRNA Vaccination on Maternal and Neonatal Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Antibody Levels

Amihai Rottenstreich, Gila Zarbiv, Esther Oiknine-Djian, Olesya Vorontsov, Roy Zigron, Geffen Kleinstern, Dana G. Wolf, Shay Porat

Research output: Contribution to journalArticlepeer-review


BACKGROUND: Coronavirus disease 2019 (COVID-19) during pregnancy and early infancy can result in severe disease. Evaluating the effect of gestational age at the time of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination on maternal antibody levels and transplacental antibody transfer has important implications for maternal care and vaccination strategies. METHODS: Maternal and cord blood sera were collected from mother-newborn dyads (n = 402), following term delivery after antenatal 2-dose SARS-CoV-2 BNT162b2 mRNA vaccination. SARS-CoV-2 spike protein (S) and receptor binding domain (RBD)-specific IgG levels were evaluated in the samples collected. RESULTS: Median anti-S and anti-RBD-specific IgG levels in maternal sera at the time of delivery were lowest following first-trimester vaccination (n = 90; anti-S IgG: 76 AU/mL; anti-RBD-specific IgG: 478 AU/mL), intermediate in those vaccinated in the second trimester (n = 124; anti-S IgG: 126 AU/mL; anti-RBD-specific IgG: 1263 AU/mL), and highest after third-trimester vaccination (n = 188; anti-S IgG: 240 AU/mL; anti-RBD-specific IgG: 5855 AU/mL). Antibody levels in neonatal sera followed a similar pattern and were lowest following antenatal vaccination in the first trimester (anti-S IgG: 126 AU/mL; anti-RBD-specific IgG: 1140 AU/mL). In a subgroup of parturients vaccinated in the first trimester (n = 30), a third booster dose was associated with significantly higher maternal and neonatal antibody levels. CONCLUSIONS: These results suggest a considerable antibody waning throughout pregnancy in those vaccinated at early gestation. The observed boosting effect of a third vaccine dose hints at its potential benefit in those who completed the 2-dose vaccine series at early pregnancy or before conception. The impact of antenatal immunization timing on SARS-CoV-2 transplacental antibody transfer may influence neonatal seroprotection.

Original languageEnglish
Pages (from-to)e603-e610
JournalClinical Infectious Diseases
Issue number1
StatePublished - 24 Aug 2022

Bibliographical note

Publisher Copyright:
© The Author(s) 2022. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail:


  • COVID-19
  • pregnancy
  • SARS-CoV-2
  • serology
  • vaccination

ASJC Scopus subject areas

  • Microbiology (medical)
  • Infectious Diseases


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