# Concordance of maternal and cord blood SARS-COV-2 immunoglobulin seropositivity after COVID-19 infection or vaccination in pregnancy

## TL;DR

This study shows that maternal SARS-CoV-2 antibodies, especially from vaccination, are effectively transferred to newborns, with higher rates in vaccinated mothers.

## Contribution

The study demonstrates higher transplacental IgG antibody transfer in vaccinated mothers compared to naturally infected ones.

## Key findings

- Maternal and cord blood IgG seropositivity showed excellent concordance.
- Vaccinated mothers had significantly higher cord blood IgG seropositivity than naturally infected mothers.
- IgM antibodies were detected in mothers but not in cord blood.

## Abstract

To assess maternal antibody response to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection during pregnancy and subsequent transplacental antibody transfer in cord blood.

This is a prospective cohort study of Coronavirus Disease 2019 (COVID-19) polymerase chain reaction (PCR) positive pregnant women and their newborns. SARS-CoV-2 PCR (+) women were enrolled, with SARS-CoV-2 PCR (−) as control. Maternal blood was obtained at enrollment and cord blood collected at delivery. Baseline maternal and infant characteristics and neonatal outcomes were collected. Samples were analyzed using coronavirus antigen microarray containing immunologically significant antigens from SARS-CoV-2 (including nucleocapsid protein [NP], spike protein [S], S1, S2, receptor-binding domain [RBD]) which can detect SARS-CoV-2 immunoglobulin G (IgG) and immunoglobulin M (IgM).

Thirty-seven maternal-cord blood paired samples were analyzed for SARS-CoV-2 IgG or IgM antibodies; 15 out of 20 samples from SARS-CoV-2 PCR (+) and 14 out of 17 from SARS-CoV-2 PCR (−) mothers were IgG positive. 14 out of the 17 SARS-CoV-2 PCR (−) mothers received COVID-19 vaccine during pregnancy. Difference between IgG seropositivity of naturally infected versus vaccinated mothers were significant, 75% versus 100% (p = 0.043). IgM antibodies were detected in 10 out of 20 SARS-CoV-2 PCR (+) women but none were detected in cord blood.

Excellent concordance of SARS-CoV-2 IgG antibodies exist between maternal and cord blood. Significantly higher SARS-COV-2 cord blood IgG seropositivity was found in vaccinated versus naturally infected mothers.