TMPRSS2 and COVID-19: Transplacental transmission of COVID-19 can occur due to the low levels of SARS-CoV-2 viremia and the decreased co-expression of angiotensin converting enzyme 2 (ACE2) and trans-membrane protease serine 2 (TMPRSS2) required for the entry of SARS-CoV-2 into placental cells [50].