The impact of maternal SARS-CoV-2 vaccination and first trimester infection on feto-maternal immune responses.

Problem: COVID-19 infection during pregnancy increases maternal and fetal morbidity and mortality. Infection in the second or third trimester leads to changes in the decidual leukocyte populations. However, it is not known whether COVID-19 infection in the first trimester or COVID-19 vaccination during pregnancy alters the decidual immune environment.

Method Of Study: We examined decidual biopsies obtained at delivery from women who had COVID-19 in the first trimester (n = 8), were fully vaccinated against COVID-19 during pregnancy (n = 17), or were neither infected nor vaccinated during pregnancy (n = 9). Decidual macrophages, NK cells, and T cells were quantified by immunofluorescence. Decidual IL-6, IL-10, and IP-10 were quantified by ELISA.

Results: There were no differences in decidual macrophages, NK cells, T cells, or cytokines between the first trimester COVID-19 group and the control group. The vaccinated cohort had lower levels of macrophages and NK cells compared to the control group. There were no differences in cytokines between the vaccinated and control groups.

Conclusions: COVID-19 infection in the first trimester did not cause significant decidual leukocyte or cytokine changes at the maternal-fetal interface. Additionally, vaccination was not associated with decidual inflammation, supporting the safety of SARS-CoV-2 vaccination during pregnancy.