MX1 and COVID-19: Of the 29 patients who tested MxA negative but were PCR positive, 12 (43%) of 28 (missing data in 1 patient) had a low viral load (Ct value of >35 or equivalent); 12 (43%) of 28 (missing data in 1 patient) had a non–COVID-19 primary diagnosis on their discharge summary, and 7 (24%) of 29 had a previous diagnosis of COVID-19 >14 days prior to the admission.