Placental transfer of SARS-CoV-2 antibodies in mother-neonate pairs: a prospective nested cohort study.

Mugo AG., Koech A., Cantrell L., Mukhanya M., Mwaniki I., Mutunga J., Voysey M., Craik R., von Dadelszen P., Le Doare K., Temmerman M., Omuse G., periCOVID-Africa ., PRECISE Network .

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. RESULTS: 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 significant difference 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.

DOI

10.1186/s12879-025-11225-6

Type

Journal article

Publication Date

2025-07-01T00:00:00+00:00

Volume

25

Keywords

COVID-19, Efficiency, Placental transfer, SARS-CoV-2 antibodies, Seropositivity, Humans, Female, Pregnancy, Antibodies, Viral, Prospective Studies, SARS-CoV-2, COVID-19, Immunoglobulin G, Infant, Newborn, Adult, Spike Glycoprotein, Coronavirus, Immunoglobulin M, Fetal Blood, Placenta, Pregnancy Complications, Infectious, Immunity, Maternally-Acquired, Kenya, Young Adult, Coronavirus Nucleocapsid Proteins, Maternal-Fetal Exchange

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