Document Type

Article

Department

Centre of Excellence in Women and Child Health; Obstetrics and Gynaecology (East Africa); Pathology (East Africa)

Abstract

Background: Newborns depend on the transfer of IgG across the placenta to acquire protection against pathogens. We assessed the placental transfer of SARS-CoV-2 antibodies, primarily derived from infection, from seropositive pregnant women enrolled in a pregnancy cohort in Kilifi, Kenya.

Methods :The study was nested within a prospective observational multi-country cohort study. All available paired maternal delivery and cord blood samples were selected. Maternal sera were tested for SARS-CoV-2 receptor binding domain (RBD) IgM/IgG total antibodies using the Wantai assay. For positive samples, maternal and corresponding cord blood samples were tested for SARS-CoV-2 IgG antibodies against the spike (anti-spike) and nucleocapsid proteins (anti-NCP) using ELISA kits from Euroimmun.

Result: A total of 492 (56.1%) out of 877 maternal delivery samples were positive for RBD IgM/IgG total antibodies. Of these, 416 (84.6%) were seropositive for either anti-NCP IgG, anti-spike IgG antibodies or both. A total of 412 out of 496 (83%) cord blood samples tested positive for either anti-NCP or anti-spike antibodies. The geometric mean ratio was 1.04 (95% CI: 0.90, 1.21), indicating no signifcant diference between the anti-spike IgG concentration in cord and maternal blood samples. The log-transformed maternal and cord blood anti-spike IgG concentrations showed a weak positive correlation (r=0.364, n=496, p< 0.001). No maternal or neonatal factors were associated with the anti-spike IgG placental transfer ratio.

Conclusion: Placental transfer of SARS-CoV-2 antibodies was evident in a population of pregnant women whose immunity was primarily derived from infection given the low SARS-CoV-2 vaccine coverage in the study area. The positive correlation between maternal and cord blood anti-spike concentrations suggests that interventions that increase maternal antibody concentrations such as vaccination may increase passive immunity and protection against severe COVID-19 disease in neonates.

Publication (Name of Journal)

BMC Infectious Diseases

DOI

https://doi.org/10.1186/s12879-025-11225-6

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Download

Share

COinS