• Increased levels of serum cytokines like TNF-α, IFN-γ, IL-2, IL-4, IL-6 and IL-10 were found in all COVID-19 patients• Similarly, CRP levels were increased in all COVID-19 patients, which showed positive correlation with IL-10• IL-6 and IL-10 levels were suggested as predictive disease severity biomarkers. This evidence concerns the gene IL10 and COVID-19.