Alterations in the Placenta Following Vaccination and Infection with SARS-CoV-2 During Pregnancy

Despite the years that have passed since the pandemic, data regarding the effects of mild SARS-CoV-2 infection and vaccination during pregnancy remain limited. The current study investigated the expression of molecules that may be involved in the placental immune response using real-time PCR and Western blot analysis in a well-characterized cohort of 118 placentas collected between the 37th and 40th week of gestation. Secreted mediators were assessed in the supernatant of placental cell cultures, and histological examinations of the placental tissue were performed. Significant differences in the expression levels of S100B, IL6, and CCL5 were observed in control versus vaccinated and previously infected women, as determined by PCR. Acute SARS-CoV-2 infection decreased the expression of p38 MAPK and Bcl-2 compared to control patients. The secretion of G-CSF, IFN-α2, IL-2, and CXCL8 (IL-8) increased in women who were infected during pregnancy and/or vaccinated. However, histological analysis revealed only minor differences between the groups. In conclusion, SARS-CoV-2 infection or vaccination during pregnancy induced a measurable placental immune response that remained below the threshold of histologically detectable tissue injury.