It has been reported that patients with COVID-19 have lower complement levels and positive autoantibodies (45, 46), while plasma concentrations of pro-inflammatory cytokines such as IFN-γ, TNF-α, IL-6, IL-1, IL-2, and IL-17 are significantly elevated, among which IL-6 is believed to be associated with the inhibition of hair shaft elongation and matrix cell proliferation (47, 48). Here, IL2 is linked to COVID-19.