BackgroundOzanimod is a novel immune modulator that could be useful in viral pulmonary infections by reducing lung inflammation. It’s an S1P receptor ligand known to induce bradycardia and more serious adverse cardiac effects such as atrioventricular block (AVB) and QT prolongation. We present a sub-study of the COZI trial where ozanimod was administered in acute pulmonary infection patients, to assess cardiac safety. MethodsIn this pilot randomized open label trial, COVID-19 patients requiring oxygen support were randomized in 2 groups: standard of care + ozanimod (OZA) versus standard of care alone (SOC). All patients were monitored with a 14-day ECG monitor (CardioSTAT®) during their hospitalization. We evaluated the cardiac effects of ozanimod on heart rate (HR), PR length, and QT duration. ResultsA total of 42 patients were analyzed: 23 in SOC and 19 in OZA. Mean hourly HR over the first 10 days of treatment decrease in OZA compared with SOC (p<0.0001). The maximum decrease in HR occurred on day 3, The maximum decrease in heart rate occurred on day 3, without significant difference between groups: 49 bpm (42-59) in OZA and 54 bpm (48-60) in SOC, p=0.45. No high degree atrioventricular block was recorded. QT and PR median values were within normal in both groups without significant difference. ConclusionThe maximal reduction in HR occurred 3 days after the onset of ozanimod treatment in patients hospitalized for COVID-19 but it did not remain significant over the 10-day treatment. No relevant cardiac adverse event was observed.