. 2021 Sep 30;12:742941. doi: 10.3389/fimmu.2021.742941

Table 2.

Comparison between non-severe and severe COVID-19.

Stage of Initial Disease	Mild-Moderate	Severe	Ref.
Symptoms	Fever, cough, fatigue, myalgia, dyspnea	Fever, cough, fatigue, myalgia, dyspnea, acute respiratory distress syndrome (ARDS) and multiple organ failure	(48, 60)
Cytokine levels	Elevated cytokines	Highly elevated cytokiens (cytokine storm)	(48, 60)
Cytokine levels	↑IL‐6, IL‐10 and TNF‐α	↑↑IL-2, IL‐6, IL-7, IL-8, IL‐10, IL-1β, IL-2R, TNF‐α and MCP‐1	(48, 60)
T cell lymphopenia	↓Lymphocytes (CD4+T and CD8+T cells)	↓↓Lymphocytes (CD4+T cells and CD8+T cells)	(48, 60, 61)
T cell lymphopenia	↓Lymphocytes (CD4+T and CD8+T cells)	↓IFNγ expressing CD4+T cells	(48, 60, 61)
Post-COVID consequences at risk	Fatigue, muscle weakness, sleep disturbance, anxiety, depression, persistent renal impairment, anosmia & ageusia, shortness of breath, brain fog	Fatigue, muscle weakness, sleep disturbance, anxiety, depression, anosmia & ageusia, shortness of breath, brain fog.	(62–65)
Post-COVID consequences at risk		Pulmonary diffusion impairment & abnormal radiological imaging (ground glass opacity & irregular lines)	(62–65)
Risk of reinfection	Modest-Significant decline in neutralising antibodies titres & seropositivity	Significant decline in neutralising antibodies titres & seropositivity	(63, 66)