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Maternal immunization status and SARS-CoV-2 antibody transfer to neonates at birth
J Gómez-Carballo1, R González-Losa1, L Conde-Ferráez1
1Centro de Investigaciones Regionales Dr. Hideyo Noguchi, Universidad Autónoma de Yucatán, Mérida, México.
Introduction:
Following the COVID-19 pandemic, hybrid immunity, arising from a combination of SARS-CoV-2 infection and vaccination, is widespread across populations, yet the dynamics of maternal antibody transfer to neonates in this context are not fully characterized.
Methods:
We conducted a cohort study of 117 pregnant women, assessing IgG antibodies against SARS-CoV-2 nucleoprotein and receptor-binding domain (RBD) in maternal, umbilical cord, and neonatal blood at delivery.
Results:
Using ELISA and pseudo virus neutralization assays, we found that 95% of mothers had detectable IgG, with 87% of neonates acquiring antibodies trans placentally. Hybrid immunity, detected in 65.5% of mothers, was associated with higher anti-RBD IgG levels in newborns compared to natural or vaccination-induced immunity alone. Neutralizing antibodies correlated positively with IgG titers, with umbilical cord samples showing the highest neutralization capacity.
Discussion:
These findings suggest that combined natural infection and vaccination in mothers enhance passive immunity in neonates, potentially improving early-life protection against SARS-CoV-2.
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