Importantly, we detected polyfunctional SARS-CoV-2 reactive CD4+ T-cells against all four proteins as well as N and S1-reactive IFN-γ CD8+ T-cells in the least severe cases, indicating that even very mild disease induces some level of protective T-cell responses, although the level of T-cell responses required for protection against COVID-19 is unknown. The gene discussed is CD4; the disease is COVID-19.