Characteristics of study participants to determine SARS-CoV-2 humoral immunity
During the time of sample collection, 10,191 patients sought medical treatment in the emergency departments. Of those patients, 1411 (13.9%) were enrolled for study participation. There was no significant difference between the age and sex distributions of all emergency department patients and the study participants, indicating the representativeness of the study sample for the source population (Supplementary Fig. 