A Possible Case of Vertical Transmission of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in a Newborn With Positive Placental In Situ Hybridization of SARS-CoV-2 RNA.

Little is known about the effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the coronavirus disease 2019 (COVID-19) on pregnant mothers and their infants. Moreover, there is no definitive evidence that SARS CoV- 2 can be vertically transmitted from an infected mother to the unborn fetus.

Maternal, neonatal and placental characteristics of SARS-CoV-2 positive mothers.

BACKGROUND: COVID19 is caused by a newly identified severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) that affects pregnant women equally to the general population. How SARS-CoV2 affects the mothers, the neonates and the placental pathology remain controversial. OBJECTIVE: To explore the effects of maternal SARS-CoV2 infection on the neonates and placental pathology in comparison to those from the normal pregnancies. STUDY DESIGN: Maternal, neonatal and placental pathology data were collected from medical records between March and August 2020 from New York Presbyterian- Brooklyn Methodist Hospital. The data from a total 142 neonates and 101 placentas from SARS-CoV2 positive mothers were compared with those from SARS-CoV2 negative mothers. RESULTS: There were 142 SARS-CoV2 positive mothers within the study group, and 43 (36%) of them showed various degrees of COVID19 related clinical symptoms including fever (13.8%), cough (5.7%), loss of taste/smell (anosmia)(5.6%), shortness of breath (2.4%), muscle ache (2.4%), headache (1.6%) and pneumonia (0.8%). A total 142 neonates were born to the SARS-CoV-2 positive mothers, and only 1 neonate tested positive for SARS-CoV2 in the first 24 h. Two additional neonates were initially tested negative in first 24 h, and later tested positive on day 7 and the 1 month visit, and all these neonates were asymptomatic and had no sequelae. There was no increase of pre-term labor and delivery or NICU admissions from SARS-CoV2 positive mothers. Examination of 101 placentas from SARS-CoV2 positive mothers and 121 placentas from SARS-CoV2 negative mothers revealed no increase of placental pathologic features. There were more vaginal deliveries and more meconium stain of fetal membranes from the SARS-CoV2 positive mothers. Previous reports of more maternal vascular malperfusion and fetal vascular malperfusion were not demonstrated in our current data. CONCLUSION: Although SARS-CoV2 is a significant risk to the pregnant women (mothers) and general population, there is no increased risk for neonates. Vertical transmission is rare, and perinatal transmission can also occur. There is no increased frequency of placental abnormalities in both maternal and fetal circulation.

SARS-CoV-2 can infect the placenta and is not associated with specific placental histopathology: a series of 19 placentas from COVID-19-positive mothers.

Congenital infection of SARS-CoV-2 appears to be exceptionally rare despite many cases of COVID-19 during pregnancy. Robust proof of placental infection requires demonstration of viral localization within placental tissue. Only two of the few cases of possible vertical transmission have demonstrated placental infection. None have shown placental expression of the ACE2 or TMPRSS2 protein, both required for viral infection. We examined 19 COVID-19 exposed placentas for histopathologic findings, and for expression of ACE2, and TMPRSS2 by immunohistochemistry. Direct placental SARS-CoV-2 expression was studied by two methods-nucleocapsid protein expression by immunohistochemistry, and RNA expression by in situ hybridization. ACE2 membranous expression in the syncytiotrophoblast (ST) of the chorionic villi is predominantly in a polarized pattern with expression highest on the stromal side of the ST. In addition, cytotrophoblast and extravillous trophoblast express ACE2. No ACE2 expression was detected in villous stroma, Hofbauer cells, or endothelial cells. TMPRSS2 expression was only present weakly in the villous endothelium and rarely in the ST. In 2 of 19 cases, SARS-CoV-2 RNA was present in the placenta focally in the ST and cytotrophoblast. There was no characteristic histopathology present in our cases including the two placental infections. We found that the placenta is capable of being infected but that this event is rare. We propose one explanation could be the polarized expression of ACE2 away from the maternal blood and pronounced paucity of TMPRSS2 expression in trophoblast.