High-dose intravenous vitamin C appears to improve oxygenation in critically ill coronavirus-infected patients. However, it does not improve invasive mechanical ventilation-free days in 28 days (IMVFD28).

A pilot, multicenter, randomized controlled clinical trial was carried to explore whether high-dose vitamin C infusion was effective to treat severe coronavirus disease 2019 (COVID-19).

The study cohort included severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected subjects in the intensive care unit. Overall, 56 participants were randomly allocated to either: (i) High-dose intravenous vitamin C cohort (12 g vitamin C diluted in 50 ml of bacteriostatic water every 12 h at a rate of 12 ml/hour by infusion pump for seven days, n=27) or, (ii) Placebo cohort (50 ml of bacteriostatic water for injection in a similar manner within 48 hours of arrival to intensive care unit, n=29). IMVFD28 was the major endpoint while organ failure (Sequential Organ Failure Assessment [SOFA] score), 28-day mortality, and inflammation advancement (interleukin-6) were the secondary endpoints.

No difference in IMVFD28 between the two groups was noted. The vitamin C group failed to lower the 28-day mortality, as shown in the following table:

During the seven-day therapy period, subjects in the vitamin C group had a constant increase in the PaO₂/FiO₂ (day 7: 229 vs. 151 mmHg), which was not noted in the control arm. Interleukin-6 in the vitamin C group was decreased compared to the placebo arm (19.42 vs. 158.00) on the 7^th day.

High-dose intravenous vitamin C failed to improve IMVFD28. However, it may display a vital benefit in oxygenation for critically ill individuals with COVID-19, with an improvement in PaO₂/FiO₂.