Table 3.

Meta-analyses conducted on the topic of VC use in COVID-19 patients.

Reference	Month, Year	No. of Studies	PICO	PRISMA	RCTs Only	Number of Patients	VC Dose	Adverse Effects	Conclusion
[190]	November–December 2021	6	YES	YES	YES	572	≥1 g daily, IV or oral	ND	No significant benefit
[192]	February 2022	7	NO	YES	NO (3 RCT, 4 retrospective studies)	807	≥2 g daily HDIVC	ND	No significance in mortality rate or disease severity
[193]	January 2022, Beran A. et al.	9	YES	YES	NO (4 RCT, 5 retrospective studies)	1488	≥1 g daily, IV or oral	ND	No significance in mortality, intubation rate, or hospitalization length
[191]	March 2022	5	YES	YES	NO (3 RCT, 2 retrospective studies)	374	≥2 g daily HDIVC	No significance	No significance in mortality rate or hospitalization length
[194]	February 2022	11	NO	YES	NO (4 RCT, 7 retrospective studies)	1807	≥1 g daily, IV or oral	ND	No significance in mortality, a longer length of stay for VC group

Abbreviations: IV—intravenous; HDIVC—high-dose intravenous vitamin C; ND—no data.