Table 1.

Summary of the main immune responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in children.

Immune System	Type of Responses
Skin and mucous membranes	IgA response in secretions; ACE2 receptor-mediated virus adhesion, and expressed less in children
Complement system	Activated by lectin pathway; inflammatory response through mediators (C3a and C5a)
Cytokines	Cytokine storm with increased IL-6, IL-2, IL-7, IL-10, and G-CSF
Mast cells	Increase in activity and histamine production
Monocytes and macrophages	Increase in number and activity
White blood cells	Normal WBC in most patients; rare lymphocytosis; lymphopenia (with low eosinophils) is the major finding in the case of altered white blood cells count