TMPRSS2 and COVID-19: Taglauer et al. conducted a maternal–fetal dyad study in patients with SARS-CoV-2, investigating the expression of ACE2 and TMPRSS2 in the placental villi of 15 pregnant patients; the study identified the spike protein of SARS-CoV-2 in placental villi in COVID-19-positive pregnancies, with and without evidence of fetal transmission [37].