A new study from the Northwestern University Feinberg School of Medicine, USA, has revealed that the COVID-19 vaccine does not damage the placenta and may be safe to use during pregnancy. Pregnant women are at a higher risk of developing infections due to a suppresed immune system. The study involved 84 vaccinated pregnant women and 116 unvaccinated patients. At the time of the study, two mRNA COVID-19 vaccines – the Pfizer-BioNTech and Moderna vaccines – had been granted emergency use authorization in the USA.
The researchers measured the SARS-CoV-2 IgM and IgG antibody levels from participants’ plasma along with antibody transfer ratios. The researchers noted that placentas of women who tested positive for COVID-19 while pregnant showed placental injury, marked by the abnormal flow between the mother and fetus in utero. Meanwhile, the researchers observed no injury to the placenta of vaccinated women who gave birth. The team also looked for abnormal blood flow between the mother and fetus and issues with fetal blood flow. The study did not find any cases of chronic histiocytic intervillositis, a complication that can happen if the placenta is infected, in vaccinated patients. Further, most pregnant women who received the COVID-19 vaccine during the third trimester had a transplacental transfer of IgG to the infant. This means that antibodies were transferred from the mother to the unborn child, providing dual protection. The observed IgG transfer ratio showed that the antibody levels in the infant were about equal to maternal levels.