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Comparative nanostructure consideration on novel coronavirus and possibility of transplacental transmission

Published:August 25, 2020DOI:https://doi.org/10.1016/j.ajog.2020.08.061
      To the Editors:
      Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or novel coronavirus infection is a new emerging viral infection that leads to coronavirus disease 2019 (COVID-19). A large outbreak of SARS-CoV-2 infection occurred in early 2020. From its first appearance, the virus spread to many countries worldwide.
      • Hsia W.
      Emerging new coronavirus infection in Wuhan, China: situation in early 2020.
      SARS-CoV-2 infection leads to respiratory disorders (COVID-19). In addition, airborne transmission of the virus from human to human is confirmed. In gynecology, the effect of COVID-19 during pregnancy needs further studies. As noted by Rasmussen et al,
      • Rasmussen S.A.
      • Smulian J.C.
      • Lednicky J.A.
      • Wen T.S.
      • Jamieson D.J.
      Coronavirus disease 2019 (COVID-19) and pregnancy: what obstetricians need to know.
      there are many issues obstetricians need to know. Of several issues, finding infection in neonates born to mothers with SARS-CoV-2 infection draws the attention of the medical society toward a possible transplacental mode of transmission.
      In fact, many viruses can cross the placenta and cause infection from the mother to the neonate. Good examples of viruses that cross the placenta are the human immunodeficiency virus (HIV) and hepatitis virus.
      • Rasmussen S.A.
      • Smulian J.C.
      • Lednicky J.A.
      • Wen T.S.
      • Jamieson D.J.
      Coronavirus disease 2019 (COVID-19) and pregnancy: what obstetricians need to know.
      • Wiwanitkit V.
      Re: HIV transmission from mother to child: an aspect on the placenta barrier at the nano-level.
      • Wiwanitkit V.
      New emerging blood-borne hepatitis viral pathogens and the feasibility of passing thorough the placenta: an appraisal.
      Based on the nanomedicine concept, the transplacental transmission of HIV is explained by the particle size of the virus and the pore size of the placenta.
      • Rasmussen S.A.
      • Smulian J.C.
      • Lednicky J.A.
      • Wen T.S.
      • Jamieson D.J.
      Coronavirus disease 2019 (COVID-19) and pregnancy: what obstetricians need to know.
      Conceptually, the viral pathogen that is smaller than the pore size of the placenta can pass the placenta and further cause neonatal infection. Applying nanostructure size analysis on the novel coronavirus, the estimated size of the virus is about 50 to 120 nm. The size of the virus is larger than the pore size of the placenta (about 10 nm). Therefore, it is unlikely that transplacental transmission of novel coronavirus can occur if there is no placental pathology. Indeed, the observations from China also show no case of vertical transmission.
      • Li Y.
      • Zhao R.
      • Zheng S.
      • et al.
      Lack of vertical transmission of severe acute respiratory syndrome coronavirus 2, China.
      The cause of SARS-CoV-2 infection in neonates could possibly be due to respiratory transmission from close contact with the mother.

      References

        • Hsia W.
        Emerging new coronavirus infection in Wuhan, China: situation in early 2020.
        Case Study Case Rep. 2020; 10: 8-9
        • Rasmussen S.A.
        • Smulian J.C.
        • Lednicky J.A.
        • Wen T.S.
        • Jamieson D.J.
        Coronavirus disease 2019 (COVID-19) and pregnancy: what obstetricians need to know.
        Am J Obstet Gynecol. 2020; 222: 415-426
        • Wiwanitkit V.
        Re: HIV transmission from mother to child: an aspect on the placenta barrier at the nano-level.
        Aust N Z J Obstet Gynaecol. 2005; 45: 539-540
        • Wiwanitkit V.
        New emerging blood-borne hepatitis viral pathogens and the feasibility of passing thorough the placenta: an appraisal.
        Clin Exp Obstet Gynecol. 2006; 33: 213-214
        • Li Y.
        • Zhao R.
        • Zheng S.
        • et al.
        Lack of vertical transmission of severe acute respiratory syndrome coronavirus 2, China.
        Emerg Infect Dis. 2020; 26: 1335-1336

      Linked Article

      • Coronavirus Disease 2019 (COVID-19) and pregnancy: what obstetricians need to know
        American Journal of Obstetrics & GynecologyVol. 222Issue 5
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          Coronavirus disease 2019 is an emerging disease with a rapid increase in cases and deaths since its first identification in Wuhan, China, in December 2019. Limited data are available about coronavirus disease 2019 during pregnancy; however, information on illnesses associated with other highly pathogenic coronaviruses (ie, severe acute respiratory syndrome and the Middle East respiratory syndrome) might provide insights into coronavirus disease 2019’s effects during pregnancy. Coronaviruses cause illness ranging in severity from the common cold to severe respiratory illness and death.
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      • Reply
        American Journal of Obstetrics & GynecologyVol. 223Issue 6
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          We greatly appreciate the interest in our work and the opportunity to respond to the issues raised. The letters by Sriwijitalai and Wiwanitkit and by Li and colleagues raise the issue of transplacental transmission of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).1,2 Since the publication of our paper online on February 24, 2020,3 several papers addressing this issue have been published, including a paper by Vivanti et al4 that provides strong evidence for transplacental transmission of SARS-CoV-2.
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