To the Editor I read with great interest the important Research Letter by Zeng et al,1 in which they describe 3 of 33 neonates from Wuhan Children’s Hospital, Wuhan, China, who had positive reverse transcription–polymerase chain reaction testing performed for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) following their operative delivery to mothers with confirmed coronavirus disease 2019 (COVID-19). All 3 infants had fever and pneumonia following birth, and 1 had comorbid conditions that may have accounted for symptoms. Fortunately, all 3 neonates survived. The authors state that maternal-fetal transmission cannot be ruled out in these cases. While I agree with that statement in principle, the reality is that in all 3 neonates, the initial testing for SARS-CoV-2 was not performed until 2 days following cesarean delivery. Zeng et al1 cited recent studies from China that have not demonstrated maternal-fetal SARS-CoV-2 transmission. Two larger and more recent reports that were not cited by Zeng et al1 included an analysis of 38 mothers with COVID-19 from China that demonstrated no instances of intrauterine viral transmission,2 and another report of 13 SARS-CoV-2–infected pregnant women in China that showed that no maternal-fetal transmission occurring.3 In many of these newly described cases there was reverse transcription–polymerase chain reaction testing of fetal specimens that included placentas, amniotic fluid, and umbilical cord blood for SARS-CoV-2 shortly after delivery, and results were all negative. No testing of these specimens was described in these 3 cases by Zeng et al,1 which, if positive, would have supported the possibility of intrauterine transmission. In previous epidemics of coronavirus diseases, such as severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), there has never been a confirmed case of intrauterine viral transmission.4 Given that maternal infections with MERS, SARS, and now SARS-CoV-2 have never been confirmed to demonstrate intrauterine transmission to the fetus, that in these 3 neonates confirmatory testing was not performed until sometime during the second day of life, and that no testing of placental tissues, amniotic fluid, or umbilical cord blood was described, the possibility of prenatal transmission appears unlikely, and it is more probable that their infection was acquired from the postnatal environment. This could occur via transmission from an infected mother or caregiver or other sources. The description of these 33 mother-infant dyads by Zeng et al1 adds significantly to our knowledge regarding COVID-19 in pregnancy. However, it is important to distinguish between viral transmission occurring in utero from that acquired shortly after birth in evaluating the source of early-onset neonatal infections, especially when there is little known of the pathophysiology and incubation period for neonatal disease owing to SARS-CoV-2.
Schwartz DA. Vertical Transmission of Severe Acute Respiratory Syndrome Coronavirus 2 From the Mother to the Infant. JAMA Pediatr. Published online July 20, 2020. doi:10.1001/jamapediatrics.2020.2135
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