Fig. 1.

Kinetics and intensity of the antiviral response are decisive in COVID-19 outcome. In mild to moderate COVID-19, the early antiviral response, mostly type-I interferon (IFN), allows the rapid reduction of viral load and prevents T-cell depletion and hypercytokinemia. In severe COVID-19, delayed (solid green line) or low (dotted green line) antiviral response results in elevated lung cytokine/chemokine levels, impaired virus-specific T-cell responses, and acute clinical deterioration. Optimal times for therapeutic interventions are proposed. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)