TNF and influenza: As an uncontrolled and dysfunctional immune response, cytokine storm shares similar immunopathogenesis in severe influenza and COVID-19, that is, releasing large amount of inflammatory cytokines such as tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), IL-12, and IL-18, thereby causing potential acute respiratory distress syndrome (ARDS) and systemic organ failure.