Comparison of SARS-CoV-2 total and neutralizing antibody transfer to neonates from vaccinated mothers vs. mothers infected during pregnancy: an observational study.

Publication date: Jul 01, 2026

Differences in antibody production against SARS-CoV-2 arise from both, infection and immunization, leading to variations in neutralization capacity and transplacental antibody transfer during pregnancy. A deeper understanding of these mechanisms can provide valuable insights into neonatal protection against viral exposure and inform the evaluation of vaccination strategies during pregnancy. This study aimed to compare the transfer of IgG and neutralizing antibodies between neonates born to mothers vaccinated against SARS-CoV-2 either during or before gestation and those born to mothers infected during pregnancy. A multicenter cohort study was conducted across four hospitals in BogotcE1, Colombia, from March to October 2023. The study assessed IgG and neutralizing antibodies in blood samples from pregnant women and umbilical cord blood from 86 mother-child pairs. The cohort comprised 40 mothers vaccinated during pregnancy (46. 5%), 35 vaccinated before pregnancy (40. 6%), and 11 infected with SARS-CoV-2 during pregnancy (12. 8%). Statistical analysis involved Fisher’s exact test for categorical variables and ANOVA for continuous variables. The Pearson correlation coefficient was employed to evaluate the correlation between maternal and umbilical cord neutralizing antibodies. Additionally, logistic regression was utilized to examine the association between neutralizing antibodies in maternal and umbilical cord blood. The proportion of patients with positive neutralizing antibodies (defined as > 20%) differed significantly between groups, with the highest percentage observed in pregnant women vaccinated before pregnancy (85. 7%). Notably, the transfer rate of neutralizing antibodies was significantly higher in infected mothers (mean = 1. 0, Interquartile Range = 1. 0-1. 2, p = 0. 014). A moderate-to-strong correlation was identified between maternal and cord neutralization percentages (r = 0. 6003), irrespective of the group. Furthermore, vaccination before pregnancy (Log Odds ratio (LOR) 3. 18 [95% CI 1. 95-4. 40]) or infection during pregnancy (LOR 2. 89 [95% CI 1. 17-4. 61]) was associated with a higher probability of achieving a higher neutralization percentage compared to those vaccinated during pregnancy. This study provided evidence of maternal antibody mediated immune response to both, SARS-CoV-2 infection and COVID-19 vaccination. The findings suggest that vaccination prior to pregnancy elicits more effective antibody responses compared to vaccination during pregnancy, highlighting the effectiveness of anti-COVID-19 vaccination prior to pregnancy.

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