| T cell responses | Lymphopenia in severe cases. |
| CD8+ cells | Severe lymphopenia, a predictor of severe COVID disease. |
| Th1-Th2 responses | Severe systemic inflammatory response accompanied by cytokine response.Plays a part in the activation of inflammasomes. |
| Eosinophils | The number of circulating eosinophils has decreased. |
| Cytokine storm | In severe disease, large numbers of innate and adaptive cytokines are released. |
| Acute phase reactants | Initial high values are predictors of severe disease. |
| Specific antibody levels | Virus-specific IgM rises during the acute phase, followed by virus-specific IgG during the recovery phase. |