TNF and infection: Further, the secondary SARS-CoV-2 infection in IAV + SARS-CoV-2 group resulted in a cytokine profile similar to that of infection with IAV alone, while the secondary infection with IAV in SARS-CoV-2 + IAV group induces a marked increase of inflammatory cytokines, including TNF-α, IL-1α, IL-6, and IFN-β in BALF suggesting differential immune responses by order of viral infections.