Sodium toxicity potentially mediates the association of SARS-CoV-2 infection and COVID-19. SARS-CoV-2 is associated with COVID-19, shown in pathway C. Sodium toxicity is a common causative factor that impairs the mucociliary clearance of noninfectious virion aggregates in the nasal mucosa, causing SARS-Cov-2 infection, shown in pathway A. Sodium toxicity also causes pulmonary edema, hyperthermia, and nasal sinus edema in COVID-19, shown in pathway B. Pathway A is potentially weak or absent in post-acute COVID-19 syndrome, and pathway B is potentially weak or absent in asymptomatic infections.