An Observational Study of Intrauterine Vertical Transmission of SARS-CoV-2 in 20 Neonates

Background: Coronavirus Disease 2019 (COVID-19) has become a global pandemic. Neonates have the risk of contracting COVID-19 through intrauterine vertical transmission, which is one of the most serious consequences of infectious diseases. Methods: We enrolled neonates and their mother, who was suffered from COVID-19 during the last trimester. We investigated the presence of SARS-CoV-2, as well as IgG and IgM against the virus in a longitudinal analysis from the labor period to one month after birth. Findings: From February 2 to March 31, 2020, of 20 neonates, 10 neonates and eight neonates had pneumonia and increased lung markings, respectively. At birth, three neonates had positive RT-PCR results of throat swabs, 16 neonates had increased IgG and/or IgM. The mean concentrations of IgG and IgM were mean [SD] 77.7 [28.4] and 11.1 [12.8] ng/mL, respectively. Among nine neonates whose antibody was measured more than once after delivery, one displayed rapidly increased IgM from 1.0 ng/mL at birth to 21.8 ng/mL at 7 days after birth, and 15 showed steadily decreasing IgM. For IgG levels, seven neonates exhibited a slowly decreasing trend after birth and two exhibited a steadily high level. At the birth time, eight neonates were at the acute phase of infection, including five with high or increased IgM and three with positive RT-PCR results. The remaining 12 neonates who had low IgM levels and negative RT-PCR were at the recovery phase. Conclusions: The study identified the presence of intrauterine vertical transmission of SARS-CoV-2, which led to various phases of infection in the neonates at birth time. Funding Statement: This study was supported by the General Program of Health and Family Planning Commission of Hubei Province of China (Grant No. WJ2017M194), the General Program of Natural Science Foundation of Hubei Province of China (Grant No. 2017CFB709), and Natural Science Foundation of Ningbo (2017A610273). Declaration of Interests: The authors declare no competing interests. Ethics Approval Statement: This observational study was reviewed and approved by the Ethics Committee of Wuhan Women and Children's Hospital and followed the Declaration of Helsinki. Written consent was acquired from the guardians of the patients.