Asymptomatic or mild
Moderate
Severe
Type I/III IFN increased and prolonged production moderate suppression high and prolonged suppression
Viral replication limited mild or chronic high and sustained
Immune response strong and rapid induction of adaptive immunity, viral clearance. NK cell and complement mediated clearance of infected cells, reduced adaptive immune responses hyperinflammation, cytokine storm e.g. IL-6, IL-8, TNFα, delayed or ineffective adaptive immune response, innate T cell activity.
Pathology none, sub-clinical tissue damage due to inflammatory response viral induced cytotoxicity, ADCC, complement mediated damage, pyroptosis, necroptosis, neutrophil driven netosis.
Vascular damage and thrombosis
no
not likely or mild
highly likely and contributes to clinical disease and tissue damage hence the finding of high levels of D-dimer produced to counteract thrombi formation.