Elevated levels of IL-2 have been reported in other types of coronavirus infections.173,174 Recent studies have also shown that the concentrations of IL-2 or IL-2R were elevated in COVID-19 patients, especially in those with severe illness.9,13,24,132 However, a clinical trial including 54 COVID-19 patients from Beijing, China, reported a contradictory result. Here, IL2 is linked to COVID-19.