Immunological assessment of SARS-CoV-2 Infection in Pregnancy From Diagnosis to Delivery: A multicentre prospective observational study

Abstract

Objective We profile the maternal and fetal response to SARS-CoV-2 infection in symptomatic and asymptomatic pregnant women and make an assessment of passive immunity to the neonate, Design Multicentre prospective study. Setting Dublin, Ireland Methods RT-PCR for viral RNA via a nasopharyngeal swab was performed using the Cobas SARS-CoV-2 6800 platform. Maternal, and fetal serological antibody response, via umbilical cord bloods, was measured using both the Elecsys® immunoassay, Abbott SARS-CoV-2 IgG Assay and the IgM Architect assay. Main outcome Measure Prevalence of RT PCR positive SARS-CoV-2. Assessment of IgM and IgG anti-SARS-CoV-2 serology antibodies. Results Ten of twenty three symptomatic women had SARS-CoV-2 RNA in a nasopharyngeal swab. Five (5/23, 21.7%) demonstrated serological evidence of anti-SARS-CoV-2 IgG antibodies and seven (30.4%, 7/23) were positive for IgM antibodies. In the asymptomatic cohort, the prevalence of SARS-CoV-2 infection in RNA was 0.16% (1/608). IgG SARS-CoV-2 antibodies were detected in 1·67% (10/598, 95% CI 0·8%-3·1%) and IgM in 3·51% (21/598, 95% CI 2·3–5·5%). Nine women had repeat testing between post baseline. Four (4/9, 44%) remained IgM positive, one IgG positive. IgG anti SARS-CoV-2 antibodies were detectable in cord bloods from babies born to five seropositive women who delivered during the study. Conclusion Using two independent serological assays, we present a comprehensive illustration of the antibody response to SARS-CoV-2 in pregnancy, and show a low prevalence of asymptomatic SARS-CoV-2. Transplacental migration of anti-SARS-CoV-2 antibodies was identified in cord blood of women who demonstrated antenatal anti-SARS-CoV-2 antibodies, raising the possibility of passive immunity.