However, another study which included 25 confirmed COVID-19 patients who were admitted to ICU showed that circulating levels of IL-2, interleukin-4 (IL-4), tumor necrosis factor-α (TNF-α), interferon (IFN-γ) and CRP were not directly correlated with symptom severity of COVID-19 [17]. This evidence concerns the gene IL2 and COVID-19.