Severe acute respiratory syndrome coronavirus 2 is known to cause respiratory infection, which can be followed by severe systemic illness. Early use of Low dose (0.5–2 g/d) vitamin C has shown benefits in severe acute respiratory syndrome coronavirus 2 infections.

Cytokine storm involving interleukin-6 and endothelin-1, which causes Severe late forms of coronavirus disease 2019, have also observed to be benefitted/reduced by the use of Vitamin C (especially at high doses).

Vitamin C supplements are rendered cheap and safe, so can be used in a low dose as prophylaxis, and can be switched to (intravenous) high-dose in cases of severe COVID-19.