Could Vitamin C Help with COVID-19?

Here are the references and my notes
Vitamin C (Ascorbic Acid)

Found in plants, citrus fruits, tomatoes, and green vegetables
Water soluble hence extra dose is peed out.
Deficiency causes scurvy
Large doses cause diarrhea

Reason that people looked into it was that the people with vitamin C deficiency had more occurrences of pneumonia.

Normal dose is 90 mg/day. Add 30 mg/day for pregnant women, and 35 mg/day for smokers.

Functions:
Antioxidant
Neutralize reactive oxygen species or free radicals.
Needed in procollagen hydroxylation during the collagen synthesis.

COVID-19 related
It helps shorten the flu duration by about 8% in adults and 14% in children
Helped prevent the occurrence of flu in people with rigorous physical activity when given in megadoses IV.
It has helped reduce the seriousness and ventilation need by patients.
A study is on going in China that will conclude in September.

Is useful in megadose
https://www.ncbi.nlm.nih.gov/pubmed/10543583
Claims that megadoses caused 85% reduction in reporting of the flu and cold symptoms.

Mixed results
https://www.healthline.com/nutrition/vitamin-c-coronavirus
Protective for the skin (collagen synthesis.)

Needed by the phagocytic cells when they are performing oxidative burst. NADPH is used to produce reactive oxygen species.

Some evidence that it reduces lung inflammation during the flu infection.

Study in Chinese language
https://mp.weixin.qq.com/s/bF2YhJKiOfe1yimBc4XwOA

Need to study the effects
https://clinicaltrials.gov/ct2/show/NCT04264533

Study that vitamin c is marginally useful in people engaged in rigorous activities.
https://www.ncbi.nlm.nih.gov/pubmed/23440782

Marginally helpful.
https://www.ncbi.nlm.nih.gov/pubmed/28353648

Maybe helpful
https://www.ncbi.nlm.nih.gov/pubmed/29099763

Helpful for the immune cells
https://www.ncbi.nlm.nih.gov/pubmed/16373990

Helpful during infections
https://www.tandfonline.com/doi/full/10.1080/14787210.2020.1706483