The validity, specificity, and reliability of the SARS-CoV-2 neutralization assay used in the current study were demonstrated by the analysis of 100 convalescent plasma donations from polymerase chain reaction (PCR)-confirmed SARS-CoV-2 cases [9] and was the basis for the correlation of function against diverse binding assays [10]. As controls, 2 plasma samples collected before the emergence of SARS-CoV-2 did not contain SARS-CoV-2 nAbs, as expected, but neutralized HCoV-229E with NT50 values of 1:43 and 1:26, respectively.