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Infectious Diseases

Poster Session 2

(554) Effect of COVID-19 variants on placental vascular pathology, with and without vaccination

Tuesday, February 13, 2024
3:30 PM – 5:00 PM  
Location: Prince George's Exhibit Hall CDE, Lower Atrium Level
Objective:

Maternal COVID-19 infection during pregnancy has been associated with higher rates of placental pathology, preterm birth, and preeclampsia, but these studies were largely done during wild-type and delta periods and prior to vaccination. This study aims to characterize the effects of COVID-19 infection during pregnancy on placental pathology through periods of recent variants of interest, with and without vaccination.

Study Design:

This was a retrospective cohort study of patients with a diagnosis of COVID-19 infection during pregnancy who delivered in 2020-2021 (wild-type/delta variant) and 2022-2023 (omicron variant), with and without vaccination. The primary outcome was placental maternal vascular malperfusion (MVM) based on Amsterdam criteria. Multivariable regression analysis was performed, controlling for race, ethnicity, and BMI.

Results:

384 patients were included: 249 controls, 60 COVID+ during 2020-2021, and 75 COVID+ during 2022-2023. Of the patients who tested positive during 2020-2021, 56 (93.3%) were unvaccinated, and during 2022-2023, 47 (62.7%) were vaccinated. There was a significant increase in the rate of MVM in the COVID+ 2020-2021 cohort compared to control, and although rates of MVM were higher in the COVID+ 2022-2023 cohort, this was not statistically significant (Table). Higher rates of MVM were seen in all COVID+ patients from 2020-2021 vs 2022-2023 (48.3% vs 24.0%, aOR 2.84 (1.33-6.05) and among unvaccinated COVID+ patients from 2020-2021 vs 2022-2023 (48.2% vs 17.9%, aOR 1.50 (1.01-2.21). Rates of preterm birth and preeclampsia were similar.

Conclusion:

There were reduced rates of placental maternal vascular pathology in patients who were COVID+ during 2022-2023 compared to 2020-2021, which may be due to a combination of different strain and pre-existing immunity in later time periods. Reduced clinical virulence of recent strains (omicron) is reflected in reduced impact on placental vascular pathology.