Qualitative and quantitative differences in SARS-CoV-2 T-cell responses have been reported across individuals with asymptomatic infection or presenting with mild or severe COVID-19; specifically, delayed appearance, weak IFN-γ/IL-2-producing, “misfiring”, dysfunctional or “exhausted” T-cell responses were seen more frequently in severe compared to mild or asymptomatic COVID-19 cases4,5,7,8,10–14. Here, IL2 is linked to COVID-19.