Reprinted courtesy Orthomolecular Medicine News Service –
(OMNS July 7, 2020) COVID-19, or SARS-CoV-2, is a coronavirus disease, classified as influenza, although coronaviruses can also induce colds, both of which are upper respiratory tract infections (URTIs).
The consequences of infection can be pneumonia, hospitalization in Intensive Care Units (ICUs), mechanical ventilation often as a consequence of cytokine storm/sepsis, and resultant organ failure and death. Studies on vitamin C and any of the conditions mentioned above are relevant to decisions as to the suitability of using vitamin C for prevention of COVID-19, as a potential therapy, and for further research.
Vitamin C for coronavirus prevention with daily vitamin C supplementation
A UK placebo-controlled trial best illustrates the meaningful clinical difference between the number of colds, cold duration and severity. A group of 168 volunteers were randomized to receive a placebo or a vitamin C supplement, two 500mg tablets daily, over a 60-day period between November and February. The researchers used a five-point scale to assess their health and recorded any common cold infections and symptoms in a daily diary.
Compared with the placebo group, the vitamin C treatment group had fewer colds (37 vs 50, P < .05), but even fewer virally challenged “cold” days (85 vs 178) and a shorter duration of severe symptom days (1.8 vs 3.1 days, P < .03). Vitamin C also reduced the number of participants who had 2 colds during their trial (2/84 on vitamin C vs 16/84 in the placebo group; P = .0004). 
And in a 2013 meta-analysis of 29 controlled trials with 11,306 participants, Hemilä showed that vitamin C shortened and alleviated URTIs that occurred during the period of vitamin C administration. In adults the duration of infections was reduced by 8% (approx half a day) and in children by 14% (approx 1 day). 
However, the dose is important. The evidence for a significant reduction in duration and severity of colds is greater and more consistent with an intake of 2,000 mg or more per day.
Given that COVID-19 is often much more severe than ordinary URTIs, the above estimates might justify a regular increased daily intake of vitamin C of at least 3,000 mg/day (in divided doses) while the prevalence of COVID-19 is high, and even more during an infection.
Supplements of other essential nutrients can also help to reduce the risk of infection; vitamin D (4000 IU/day), magnesium (400 mg/day), and zinc (20 mg/day) are recommended. [3-5]
Vitamin C for coronavirus treatment – taking vitamin C during infection
While a relatively small amount of vitamin C is sufficient for healthy people, its effective use depends on how much is required to support the immune system. When a person is infected, the amount required increases dramatically.
This is illustrated by the depletion of vitamin C levels in leucocytes, critical for immune response, during colds and flu. These critical immune cells normally have more than 10-fold higher vitamin C levels than other cells.
An intake of 6 g/day has been shown to restore normal vitamin C levels in leucocytes during colds.  This suggests that similar daily doses may be required to have a symptom reducing effect. Studies giving 3 vs 6  or 4 vs 8 g/day  have shown the higher the dose the greater the effect with a 20% decrease in cold duration with 6 to 8 g/day.
This equates to 1.5 to 2 days shorter colds. However, 46% of those taking 8 g/day in the first day of a cold report being symptom free after 24 hours. Case reports indicate greater effect with doses of 15+ g/day, titrating the dose to “bowel tolerance” levels.  During an infection most people can tolerate 1 g/hr without diarrhea. This was Dr. Linus Pauling’s recommendation — to start with a loading dose of 2,000 – 3,000 mg, then take 1,000 mg/hr until symptoms disappear.
Vitamin C for hospitalized & ICU patients with pneumonia, sepsis or COVID-19
Vitamin C supplementation has been shown effective, even at low doses between 200 mg and 1600 mg/day, in reducing incidence, speeding up recovery and reducing mortality in those with pneumonia. [10,11]
A recent study by Carr has reported depleted plasma vitamin C status (23 µmol/L) in 44 hospitalized patients with pneumonia, compared to healthy controls (56 µmol/L).  The most severe patients in ICU had levels averaging 11 µmol/L, which is the level that defines scurvy.
Marik has reported similar findings in 22 ICU patients with sepsis with levels of 14.1 µmol/L  and recommends giving 1.5 g of vitamin C every 6 hours intravenously.  Marik has also reported that all COVID-19 patients in ICUs so far tested by his group (Frontline Covid-19 Critical Care – FLCCC) have deficient or undetectable levels of vitamin C sufficient to diagnose scurvy. 
Vizcaychipi, at the Chelsea and Westminster NHS Hospital, using 1g vitamin C every 12 hours, has reported a mortality rate (25.1% in females and 38.2% in males) 21% lower than the UK national average (ICNARC data) of 49%, thus saving one in five lives. 
Vitamin C to prevent or shorten ICU hospitalization, mechanical ventilation and mortality
One of the major causes for concern with COVID-19 is the relatively high proportion of cases requiring intensive care unit (ICU) treatment. Hemilä’s meta-analysis of 12 trials with 1,766 non-COVID patients in ICU found that vitamin C shortened ICU stay by 8%.  Another meta-analysis of eight trials found that vitamin C shortened the duration of mechanical ventilation in patients who required the longest ventilation. 
There is evidence that vitamin C levels decline precipitously in critically ill patients, and that administration of an appropriate dose can dramatically reduce complications and mortality.  Although 100 mg/day of vitamin C can maintain a normal plasma level in a healthy person, much higher doses (1,000 – 4,000 mg/day) are needed to increase plasma vitamin C levels of critically ill patients to within the normal range. 
For hospital patients in critical care, the FLCCC give 3,000 mg of intravenous vitamin C every six hours, together with steroids and anti-coagulants. FLCCC are reporting zero COVID-19 deaths in their ICUs in those without end-stage co-morbidities. 
A randomized, placebo-controlled trial in Wuhan of mechanically ventilated ICU patients given either 12 g of intravenous vitamin C twice daily or sterile water placebo in a saline drip shows preliminary results of 24% mortality on the vitamin C group vs 35% in the placebo group. The study showed significant results in the reduction of the inflammatory marker IL-6 and of mortality in those with the worst pulmonary function index (PF < 150). 
A variety of studies have shown that high-dose oral supplements of vitamin C and other essential nutrients such as vitamin D, magnesium, and zinc, can lower the risk of viral infection and COVID-19 and effectively reduce the intensity of infections. In a hospital ICU setting high-dose oral and IV vitamin C in combination with a well-established critical care protocol can treat COVID-19 to prevent serious pneumonia, need for mechanical ventilation, organ failure, septic shock, and death.
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- Hemilä H, Chalker E. (2013) Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev. 2013 Jan 31;(1):CD000980. https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD000980.pub4/full
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- Hemilä H (2017) Vitamin C and Infections. Nutrients 9: 339 https://www.mdpi.com/2072-6643/12/5/1318″ target=”_blank. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5409678
- Player G, Saul AW, Downing D, Schuitemaker G (2020) Published Research and Articles on Vitamin C as a Consideration for Pneumonia, Lung Infections, and the Novel Coronavirus (SARS-CoV-2/COVID-19). Orthomolecular Medicine News Service. http://orthomolecular.org/resources/omns/v16n20.shtml
- Carr AC, Spencer E, Dixon L, Chambers ST (2020) Patients with community acquired pneumonia exhibit depleted vitamin C status and elevated oxidative stress. Nutrients 12:1318. https://www.mdpi.com/2072-6643/12/5/1318
- Marik PE, Khangoora V, Rivera R, et al. (2017) Hydrocortisone, Vitamin C and thiamine for the treatment of severe sepsis and septic shock: A Retrospective Before-After Study. Chest. 151:1229-1238. https://pubmed.ncbi.nlm.nih.gov/27940189
- Marik PE, Hooper MH (2018) Doctor — your septic patients have scurvy! Critical Care 22:23. https://ccforum.biomedcentral.com/articles/10.1186/s13054-018-1950-z
- Marik PE (2020) Unpublished data. In podcast, Holford P, April 28, 2020: Flu Fighters Series. Ep. 4: The Sharp End of Treatment – How Intravenous Vitamin C is Saving Lives. https://patrickholford.podbean.com/e/flu-fighters-series-1-ep-4-use-of-intravenous-vitamin-c-for-front-line-staff.
- Vizcaychipi MP, Shovlin CL, Hayes M, et al. (2020) Early detection of severe COVID-19 disease patterns define near real-time personalised care, bioseverity in males, and decelerating mortality rates. Preprint at https://www.medrxiv.org/content/10.1101/2020.05.08.20088393v1
- Hemilä H, Chalker E. (2019) Vitamin C can shorten the length of stay in the ICU: a meta-analysis. Nutrients. 11:708 https://www.mdpi.com/2072-6643/11/4/708
- Hemilä H, Chalker E. (2020) Vitamin C may reduce the duration of mechanical ventilation in critically ill patients: a meta-regression analysis. J Intensive Care 8:15. https://jintensivecare.biomedcentral.com/articles/10.1186/s40560-020-0432-y
- Carr AC, Rosengrave PC, Bayer S, et al., (2017) Chambers S, Mehrtens J, Shaw GM. Hypovitaminosis C and vitamin C deficiency in critically ill patients despite recommended enteral and parenteral intakes. Crit Care 21:300; see also . https://pubmed.ncbi.nlm.nih.gov/29228951
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- Frontline COVID-19 Critical Care Alliance (2020) The MATH+ protocol is a physiologic-based treatment regimen created by leaders in their field. https://covid19criticalcare.com
- Peng Z (2020) Personal communication, 10th April 2020. Publication pending.