Fig. 3.

Immunological events that occur in individuals who develop asymptomatic/mild to moderate symptoms of COVID-19 following exposure to SARS-CoV-2. Infection can be cleared by neutralizing antibodies (nabs). Upon recognition of foreign invaders via pattern recognition receptors (PRRs), macrophages secrete type I interferons that lead to an antiviral state. In addition, these macrophages phagocytose virus-infected cells that could have been opsonized by the nabs, carry out efficient antigen presentation to T cells, clear all the debris in the lungs, and resolve inflammation. As a result, highly functional T cells (CD4+ T cells expressing high levels of IFNγ and increased CD8+ T cell cytotoxicity) are obtained.