There are differences in immunopathological mechanisms between children and adults, including: lower ACE2 expression in nasal epithelium, lower ACE2 to SARS-COV-2 affinity and lower TPMRSS2 expression in children; more efficient innate immunity, due to trained immunity and better interferon type I response in children; stronger adaptive T-cell response in children, with less frequent lymphopenia (8, 29–31). This evidence concerns the gene ACE2 and lymphopenia.