Evidence for the potential transmission of SARS-CoV-2 via the placenta from a mother, who tested positive for the virus, to her baby is reported in a case study published in Nature Communications.
Previous studies have suggested that perinatal (the period immediately before and after birth) transmission of SARS-CoV-2 may occur, but it is unclear if this takes place via the placenta, a cervical route or as a result of environmental exposure.
Daniele De Luca and colleagues present the results from a case study, which suggests that transplacental transmission of SARS-CoV-2 may be possible. A pregnant woman in her twenties was admitted to hospital with a fever and severe cough. Blood tests, and nasopharyngeal and vaginal swabs confirmed the presence of the SARS-CoV-2 ‘E’ and ‘S’ genes (which encode the viral envelope and spike protein, respectively). Nasopharyngeal and rectal swabs collected from the baby an hour after delivery by caesarean section and then again 3 and 18 days later, also tested positive for the presence of the ‘E’ and ‘S’ genes. Newborn blood and bronchoalveolar lavage were also positive. The authors observed that the infant presented with neurological symptoms associated with infection by the virus, similar to those reported in adult patients. Neuroimaging analyses indicated white matter injury, which the authors speculate can be caused by vascular inflammation induced by SARS-CoV-2 infection. No other viral or bacterial infections were found and all other neonatal disorders potentially causing these clinical symptoms were excluded. Both mother and child recovered from the infection and were later discharged from hospital.
De Luca and co-authors also measured higher viral loads in the placenta than in the amniotic fluid and maternal blood, which suggests that SARS-CoV-2 might actively replicate in placental cells and cause neonatal viremia. This was consistent with levels of inflammation seen in a histological examination of the placenta. By confirming the presence of SARS-CoV-2 in the placental tissue, and the maternal and neonatal blood, the authors conclude that transmission from mother to baby most likely occurred through the placenta. Further studies will be needed to confirm these results.
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