Rearchers at IREC (OBST Lab) and Cliniques Universitaires Saint-Luc have shown that the placenta is not susceptible to SARS-CoV-2 infection, making a transmission to the neonate unlikely to occur around term.
Over a year, the COVID-19 pandemic has become a worldwide health and social crisis, deeply affecting human lives and questioning the future of humankind. In this context, pregnant women are particularly vulnerable and maternofetal transmission of SARS-CoV-2 remains a matter of investigation since very few neonates have shown evidence of contamination following maternal infection. This study highlights that the trophoblasts, the cells constituting the maternofetal interface at term, are not infectable by SARS-CoV-2.
In a cohort of 31 pregnant women with maternal COVID-19, we first characterized the viral expression and clinical/immune responses of the mother-infant dyad to SARS-CoV-2 infection. We only detected one case of positive placenta, which was unfortunately associated with the fetal demise before the pregnancy term. Then, using a combination of histological observations and culture of human primary cells, we demonstrated that the trophoblasts are resistant to SARS-CoV-2, probably because one or several of the proteins necessary for viral entry are missing at the surface of the cells.
These results are reassuring for the mothers contracting COVID-19 at term. However, our study raises concern about preterm infection, making pregnant women a priority during the vaccination campaign.