PROS1 and COVID-19: In the study reported by Jennewein et al. (37), only one MAb CV3-25 out of 87 anti-S2 mAbs among 198 antibodies isolated from four COVID-19 patients was capable of neutralizing SARS-CoV-2 and SARS-CoV and of binding the S proteins of the human betacoronaviruses OC43 and HKU1.