Section 3: Conclusions and priorities for future research (from DOI: 10.1016/j.jcv.2020.104372)
From publication: "SARS-CoV-2: Is it the newest spark in the TORCH?" published as J. Clin. Virol.; 2020 Apr 14 ; 127 104372. DOI: https://doi.org/10.1016/j.jcv.2020.104372
Section 3: Conclusions and priorities for future research
Although more knowledge is needed, we would submit that the SARS-CoV-2 virus is, in some cases, transmitted from mother-to-fetus, and that this virus should be included in our working list of TORCH infections. Animal models demonstrate the vertical transmission of related animal coronaviruses in pregnancy, and evidence of vertical transmission has been reported in parturient women with COVID-19 disease. Although more data about transplacental infections is needed, studies in women undergoing Cesarean delivery are highly suggestive of in utero transmission. The fact that SARS-CoV-2 has been demonstrated to produce RNAemia further suggests the biological plausibility of transplacental transmission by a mother-to-fetus hematogenous route. SARS-CoV-2 can also be found in fecal samples, suggesting that perineal colonization could lead to intrapartum infection of the newborn during labor and delivery. Reports from China suggest, based on limited assessment of IgM serology and virologic samples in neonates, that vertical transmission of virus does occur in some cases. On the other hand, a recent report from Columbia University in New York found no evidence for vertical transmission in 43 COVID-19-positive pregnant women: moreover, this study also demonstrated that a high percentage (32.6 %) of infected women were, in fact, asymptomatic upon their original clinical presentation. Increased availability of testing, including real-time "point-of-care" testing, should help clarify the risks of transmission to the fetus.
High-priority areas for future studies are highlighted in Table 2 . Foremost among these will be the determination of potential modes of transmission in the newborn period - i.e., transplacental versus intrapartum versus postpartum. The finding of SARS-CoV-2 RNA in the first few days of life could represent bona fide congenital infection, acquired before birth; transient colonization acquired during labor and delivery; or post-natal acquisition via droplet spread from an infected mother. Strategies must be enhanced to differentiate among these possibilities. The issue of breastmilk transmission also requires further study. Examination of placentas from COVID-19 positive women for virologic and histologic markers of infection should be a high-priority area for investigation. Maternal and nenonatal biomarkers (possibly IL-6) that correlate with maternofetal transmission should also be studied. Optimal infection control procedures in the newborn period must be defined toward the goal of resolving the best strategies to prevent post-natal infection. Finally, the pregnant patient should be considered a top priority recipient of candidate vaccines and immunotherapies. It is premature to recommend antivirals or immune-based therapies (such as monoclonal or polyclonal anti-COVID 19 antibodies) aimed at interrupted perinatal transmission, but such strategies deserve consideration; in this context, efforts that have been considered and studied to block CMV transmission during pregnancy can be highly instructive. Ultimately, an effective vaccine is of the highest priority. A vaccine will not only protect maternal health during pregnancy and delivery, but also can likely minimize the risk of fetal and neonatal infection by potentially inducing transplacental antibodies that may help prevent infection from other household and community exposures. Vaccines stand the best chance for reducing the risk of both in utero transmission, and post-natal mother-to-infant transmission in the newborn period.
