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Poster Session 2

Category: Clinical Obstetrics

Poster Session 2

(620) Divergent Maternal–Fetal Immune Signatures After SARS-CoV-2 Vaccination Versus Infection: High-Dimensional Cytometry Across the Placenta

Wednesday, February 11, 2026

3:30 PM - 5:00 PM

Submitting Author and Presenting Author(s)

OG

Ola Gutzeit, MD

Rambam Health Care Campus
Haifa, Hefa, Israel

Coauthor(s)

Roee Iluz, MD

Rambam Health Care Campus
Haifa, Hefa, Israel
Michael G. Ross, MD, MPH

Distinguished Professor
Harbor-UCLA Medical Center
The Lundquist Institute at Harbor-UCLA Medical Center, California, United States
NK

Nizar Khatib, MD

Rambam Health Care Campus
haifa, Hefa, Israel
Yuval Ginsberg, MD (he/him/his)

Deputy Ob/Gyn department
Rambam
Israel, Hefa, Israel
ZW

Zeev Weiner, MD

Director of the Obstetrics and Gynecology Division
Rambam Health Care campus
Haifa, Hefa, Israel
RB

Ron Beloosesky, MD

Rambam Health Care Campus
Rambam Health Care Campus, Hefa, Israel

Objective:
To compare maternal and neonatal immune profiles following SARS-CoV-2vaccination versus natural infection during pregnancy using high-dimensional cytometry.

Study Design:
We conducted a prospective cohort study at a single tertiary center. Peripheral and cord blood samples were collected at delivery from three groups: unvaccinated controls, pregnant individuals vaccinated with mRNA-COVID-19 vaccine, and individuals with resolved mild SARS-CoV-2 infection 4–8 weeks prior. Samples were profiled using a 30-marker CyTOF panel. Immune populations were clustered using FlowSOM to identify 50 metaclusters. Statistical comparisons were performed using ANOVA/Tukey or Kruskal–Wallis/Dunn tests, and UMAP was used for dimensionality reduction.

Results:
Maternal SARS-CoV-2 infection led to broad immune suppression: neutrophils decreased (49%→28%), classical monocytes (28%→3%), Th17-like CD4⁺ (MC46, p< 0.05), and central memory CD4⁺ T cells (MC48, p< 0.01) were reduced. CD8⁺ T cells were also affected, with MAIT precursor/memory (MC19, p< 0.001) and naïve CD8⁺ T cells (MC29, p< 0.01) significantly reduced. Naïve CD4⁺ T cells (MC49) were decreased in both mothers and neonates. Neonates of infected mothers showed neutrophil loss (69%→36%), increased immature NK cells (2%→7%), naïve B cells, and CD8⁺ TEMRA cells (0.11%→0.14%, p=0.01). Naïve B cells (MC8) diverged—decreased in mothers but increased in neonates (5%→14%, p=0.024). In contrast, vaccinated dyads (mothers and neonates) retained immune profiles comparable to uninfected controls across major leukocyte subsets.

Conclusion:
SARS-CoV-2 infection during pregnancy induces systemic maternal immune suppression, particularly affecting monocytes and adaptive T cell subsets, with parallel expansion of naïve and immature lymphoid populations in the fetus. In contrast, mRNA vaccination preserves immune balance across the maternal–fetal interface.