CD4 and COVID-19: Effective viral clearance and mild COVID-19 following SARS-CoV-2 infection are associated with an early innate immune response [1,13] followed by a virus-specific CD8+ T-cell response (within 7 days of symptoms and peaking after 14 days, mirroring antibody kinetics) and mobilization of CD4+ T helper type 1 cells [14].