Table 1.

Published RCTs on intervention with Vitamin C and Zn supplement in COVID-19 patients.

Author, year (ref)	Country	Type of study	Participants	Number of I/C	Intervention	Control	Duration	Results
JamaliMoghadamSiahkali, et al., 2021 [65]	Iran	RCT	Severe COVID-19	30/30	High dose Vitamin C (6 g/daily)	lopinavir/ritonavir and hydroxychloroquine	5 days	Body temperature ↔ SpO2 ↔ Length of hospitalization ↑ Length of ICU stay ↔ Mortality ↔
Thomas et al., 2021 [66]	USA	RCT	COVID-19	Group 1: 58, group 2: 48, group 3: 58/50	Group 1: Zn gluconate (50 mg) Group 2: ascorbic acid (8000 mg) Group 3: both supplement	Standard of care	10 days	Fever ↔ Cough ↔ Shortness of breath ↔ Fatigue ↔ Hospitalization ↔ Death ↔
Abd-Elsalam et al., 2021 [67]	Egypt	RCT	COVID-19	96/95	Chloroquine/hydroxychloroquine and Zn sulfate (220 mg contains 50 mg Zn/twice daily)	Chloroquine/hydroxychloroquine	15 days	Hemoglobin ↔ Platelets ↔ WBCs ↔ Direct bilirubin ↔ Indirect bilirubin ↔ Albumin ↔ ALT ↔ AST ↔ D-dimer ↔ Ferritin ↔ Creatinine ↔ CRP ↔ Duration of hospital stay in days ↔ Recovery after 28 days ↔ Need for mechanical ventilation ↔ Survived ↔
Patel et al., 2021 [68]	Australia	RCT	COVID-19	15/18	Elemental Zn concentration, 0.24 mg/kg/day	Saline placebo	7 days	Serum Zn ↑ Mean daily peak oxygenation requirement ↔ Number of patients with supplemental oxygen ↔ Number of patients with NIV, and/or HFNC ↔ Number of patients with mechanical ventilation ↔

RCT, randomized controlled trial; Spo2, Peripheral capillary oxygen saturations; ICU, intensive care unit; WBC, white blood cell; ALT, alanine aminotransferase; AST, aspartate aminotransferase; CRP, C-reactive protein; HFNC, high-flow nasal cannula, NIV, noninvasive ventilation.