Serum inflammatory factor levels of IL-2, IL-1β, IL-5, IL-4, IL-6, IL-8, IL-10, IL-17, IL-12P70, IFN-α, TNF-α, IFN-γ, endotoxin, CRP, and hs-CRP of non-severe COVID-19 patients across different age groups (< 50, 50–60, 60–70, and ≥ 70 years) were not significantly different (Table 3). Here, IL17A is linked to COVID-19.