Covid-19 living Data

Pharmacologic treatments for covid-19 patients

Vitamin C vs Standard of care/Placebo

This comparison will not be updated. Last search date 22 Oct, 2021.

Outpatients

Forest plots
(last update: 2022-04-29)

Hospitalized patients

Forest plots
(last update: 2021-05-27)

Summary of findings
(last update: 2021-06-01)

Patient or population: COVID-19 patients
Setting: Worldwide
Intervention: Vitamin C
Comparison: Standard of care/Placebo

Outcome	Relative effect (95% CI)	Absolute effect (95% CI)¹		Certainty of the Evidence (GRADE)
Clinical improvement D28	Outcome not yet measured or reported
Clinical improvement D60	Outcome not yet measured or reported
WHO progression score (level 7 or above) D28	Outcome not yet measured or reported
WHO progression score (level 7 or above) D60	Outcome not yet measured or reported
All-cause mortality D28	RR: 0.64 (0.27 - 1.53)	124 fewer per 1000 (from 252 fewer to 183 more)		Very low certainty Reasons to downgrade Risk of bias: Not serious Despite some concerns with deviations from intervention, not downgraded for risk of bias Inconsistency: Not serious Indirectness: Serious despite a multicentre design this is a single study from a single country, therefore results in this population might not be generalizable to other settings. Imprecision: Very serious Imprecision downgraded by 2 levels: due to wide confidence interval consistent with the possibility for benefit and the possibility for harm and very low number of participants
1 trials Zhang J, 2020 56 participants		Vitamin C 221 per 1,000 (93 - 528)	Standard of care/Placebo 345 per 1,000
All-cause mortality D60	Outcome not yet measured or reported
Viral negative conversion D7	Outcome not yet measured or reported
Adverse events	RR: 36.43 (2.25 - 589.34)	Absolute effects were not calculated due to zero events in the control group		Very low certainty Reasons to downgrade Risk of bias: Serious Risk of bias downgraded by 1 level: some concerns regarding deviations from intended interventions, missing data and outcome measurement Inconsistency: Not serious Indirectness: Serious Indirectness downgraded by 1 level: despite a multicentre design this is a single study from a single country, therefore results in this population might not be generalizable to other settings. Imprecision: Serious due to low number of participants/events
1 trials Thomas S, 2021 98 participants		Vitamin C 0 per 1,000 ( - )	Standard of care/Placebo 0 per 1,000
Serious adverse events	Outcome not yet measured or reported

¹The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI)

CI: Confidence interval; RR: Risk ratio

GRADE Working Group grades of evidence
High certainty: We are very confident that the true effect lies close to that of the estimate of the effect
Moderate certainty: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low certainty: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low certainty: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

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Permanent URL for this comparison: https://covid-nma.com/living_data/index.php?comparison=63

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Trial	Funding	Comparisons		Design	Participants	Sample size	Overall risk of bias Highest assessment	Full description
		Treatment 1	Treatment 2
NCT04342728 COVID A to Z Thomas S, JAMA Netw Open, 2021 Full text Commentary Commentary	Not reported/unclear	Vitamin C Zinc Vitamin C+Zinc Vitamin C Vitamin C Zinc	Standard care Standard care Standard care Vitamin C+Zinc Zinc Vitamin C+Zinc	RCT	Outpatients with confirmed COVID-19 (asymptomatic-mild) treated by multiple centers in the US.	N=214	Some concerns Details	Full description
IRCT20200411047025N1 JamaliMoghadamSiahkali S, Eur J Med Res, 2021 Full text Commentary	Public/non profit	Vitamin C	Standard care	RCT	Patients with suspected or confirmed COVID-19 (severe) admitted to a single center in Iran	N=60	N/A	Full description
N/A Kumari P, Cureus, 2020 Full text Commentary Commentary	No specific funding	Vitamin C	Standard care	RCT	Patients with COVID-19 (severe) admitted to a single center in Pakistan	N=150	N/A	Full description
NCT04264533 Zhang J, Ann. Intensive Care, 2021 Full text Commentary	Public/non profit	Vitamin C	Placebo	RCT	Patients with confirmed COVID-19 (severe-critical) admitted to 3 centers in China	N=56	Some concerns Details	Full description