Table 1.

Effect of VC treatment/supplementation among COVID-19 patients.

Study Design	Patients	Dose of VC	Results	References
Case report	A 74-year-old woman	1 g twice a day (for a total of 10 days)	fewer days on mechanical ventilation; shorter ICU stay; earlier recovery	[42]
Case series	17 patients	1 g every 8 h for 3 days	reduced mortality; reduced number of intubations; decreased inflammatory markers (ferritin and D-dimer); reduced need for FiO2	[38]
Retrospective case series	12 patients	A median of 162.7 (71.1–328.6) mg/kg (body weight)/day in severe patients, and 178.6 (133.3–350.6) mg/kg/day in critical patients	significant decrease in C-reactive protein, lymphocyte, and CD4+ T-cell counts; improvement of PaO2/FiO2; improvement of SOFA score	[43]
Case report	A 29-year-old man	VC treatment together with inhalation therapy	the patient died of tension pneumothorax	[44]
Case report	2 patients (a 50-year-old and a 71-year-old man)	200 mg/kg/day, for 96 h	an adverse effect associated with high-dose intravenous VC administration; ATI and oxalate nephropathy are likely caused by excessive VC	[45]
Retrospective study	102 patients	73 patients received supplementation with VC and zinc	high mortality no change in overall survival of patients	[46]
Open-label, randomized, and controlled trial	30 patients with severe COVID-19 infection	1.5 g of IV VC every 6 h for 5 days plus lopinavir/ritonavir and oral hydroxychloroquine vs. lopinavir/ritonavir and oral hydroxychloroquine alone	no difference in the length of ICU stay, intubation rate, or mortality rate	[47]
Open-label, randomized, and controlled trial	75 patients	50 g/kg/day	no significant difference was found in the need for mechanical ventilation or mortality	[48]

ICU—intensive care unit; SOFA—Sequential Organ Failure Assessment score; ATI—acute tubular injury; COVID-19—coronavirus disease 2019.