TNF and COVID-19: Compared to mild cases, patients with severe COVID-19 have markedly increased levels of pro-inflammatory cytokines, including IL-1, IL-2, IL-6, IL-8, IL-10, IL-12, IL-17, tumor necrosis factor (TNF)-α and IFN-γ (Sinha et al., 2020; Tay et al., 2020).