SARS-CoV-2 infection vs. vaccination during pregnancy: the placenta leads the way.

PURPOSE OF REVIEW: To understand the characteristics and determinants of transplacental antibody transfer against SARS-CoV-2 and to compare the differences between SARS-CoV-2 infection and vaccination.

RECENT FINDINGS: The need for information during the COVID-19 pandemic and the exclusion of pregnant women from randomized clinical trials have led to a vast amount of clinical data primarily based on observational studies with diverse design and sample analyses that yield variable results. This review aims to critically and comprehensively integrate the relevant knowledge related to transplacental transfer of antibodies against SARS-CoV-2, emphasizing the differences between infection and vaccination.

SUMMARY: Passive immunization is key to conferring protection to the infant during their first months of life. Understanding the mechanisms of transplacental antibody transfer during SARS-CoV-2 infection and vaccination, and their associated protection will allow optimizing the implementation of well tolerated and effective preventive strategies for both pregnant women and infants.