LB01 - Maternal Antibody Response and Placental Antibody Transfer following Asymptomatic and Symptomatic SARS-CoV-2 Infection
Thursday, January 28, 2021
12:30 PM – 12:45 PM EST
Objective: This prospective cohort study characterized the immune response to the SARS-CoV-2 virus during pregnancy.
Study Design: Paired maternal and cord blood samples were collected at the time of delivery from women who tested positive for SARS-CoV-2 RNA at any point during pregnancy. Difference in transmission of immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies across the placenta were analyzed according to symptomatic vs asymptomatic infection and latency from time of infection to delivery. Sera was tested for the presence of anti-SARS-CoV-2 IgG and IgM antibodies using an enzyme-linked immunosorbent assay (ELISA) developed against the receptor binding domain (RBD) of the SARS-CoV-2 spike protein (Suthar et al, 2020).
Results: A total of 23 paired maternal-infant dyads were included in the study. The mean gestational age at diagnosis was 37.7 weeks’ ( 1.2, range 31.0 – 40) and the mean gestational age at delivery was 38.4 ( 0.3, range 34.4 – 40.1). All maternal delivery serum samples had detectable SARS-CoV-2 IgG antibody (n=23) and 91% had detectable SARS-CoV-2 IgM (n = 21). Among cord blood samples, 87% had detectable SARS-CoV-2 IgG (n= 20), while 13% had detectable SARS-CoV-2 IgM antibody (n=3). In stratifying the study sample based on latency from initial SARS-COV-2 test positive to delivery, there were no significant differences in the end point titers of maternal or cord blood IgG or IgM levels (Figure 1). Similarly, no significant differences were found based on indication for testing (asymptomatic testing vs symptomatic/person under investigation - Figure 2). All three cord blood samples with detectable SARS-CoV-2 IgM antibodies were from symptomatic women (Figure 2).
Conclusion: These data demonstrate that pregnant women in this cohort almost uniformly mounted an IgG and IgM response to SARS-CoV-2, even if asymptomatic at the time of diagnosis; almost all samples showed robust transfer of IgG antibodies into the cord blood. These results form a promising foundation for further investigation into the maternal humoral response to SARS-CoV-2 infection in pregnancy.