Current standard protocols of RT-PCR of nasopharyngeal swab in neonatal patient is not sensitive enough for determination of vertical transmission

Abstract

The pandemic experienced in recent months has raised questions that should be investigate in the clinical practice. Transplacental transmission of SARS-CoV-2 and the consequences to the fetus and newborn have called attention due to the increasing number of infections, contradicting previous evidences that there was no possibility of coronavirus transmission from the mother to the fetus. We presented three cases of pregnant women with positive SARS-CoV-2 antibodies serology on admission in Naval Hospital Marcílio Dias (HNMD), Rio de Janeiro, Brazil. Samples of umbilical cord blood was double positive (IgM and IgG) for one patient, double negative for one patient and positive for IgG and negative for IgM for third patient. Maternal and neonatal nasopharyngeal swab samples analyzed by PCR for SARS-CoV-2 was positive for two maternal patients and negative for all newborns tested. It was possible to detect the SARS-CoV-2 in amniotic fluid and umbilical cord blood using the nested-PCR technics, thus being successfully evidenced transplacental transmission. We suggested that nasopharyngeal swab PCR test of neonates does not have a correlation with vertical transmission and thus, this molecular test is not useful for investigation of transplacental infection.