In post-acute COVID-19, the concentration of serum IL-6 was found to be 1.45 ± 2.1 pg/mL, 1.96 ± 1.9 pg/mL, and 4.43 ± 6.6 pg/mL in patients with anamnesis of mild, moderate, and severe COVID-19, respectively, where the severity of the disease was characterized according to the need of medical treatment: mild, outward treatment; moderate, inward treatment; severe, inward treatment respiratory support (oxygen supply or mechanical ventilation) [46]. This evidence concerns the gene IL6 and COVID-19.