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The Association of Two Pandemics: COVID-19 and Vitamin D deficiency by Dr Michael Traub

March 11, 2020, the World Health Organization announced the novel coronavirus disease (COVID-19) outbreak to be a global pandemic. The incidence of new COVID-19 cases has continued to accelerate, while the incidence of new deaths has remained relatively stable.  As of October 18, over 40 million cases and 1.1 million deaths had been reported globally, with over 2.4 million new cases and 36,000 new deaths reported in the preceding week. (1)

Vitamin D deficiency has also been described as pandemic, especially in Europe. Regardless of age, ethnicity, and latitude, recent data show that 40% of Europeans are vitamin D deficient (25-hydroxyvitamin D (25(OH)D) levels <50 nmol/l), and 13% are severely deficient (25(OH)D < 30 nmol/l). (2)

Risks for vitamin D deficiency include obesity, elderly, lack of sun exposure, dark skin, smoking, exposure to air pollution, and co-morbidities such as infection, cancer, cardiovascular disease, chronic respiratory disease, osteoporosis, sarcopenia, and diabetes mellitus. It is clear that severe vitamin D deficiency dramatically increases the risk of mortality, infections, and many other diseases. As such, it should indisputably be prevented whenever possible. (3)

These overlapping pandemics have been termed “scientific strabismus,” and due to the urgent nature of the coronavirus pandemic, the association of COVID-19 and vitamin D deficiency has become an active area of research. However, the available data currently are preliminary in nature, due to the fact that the pandemic began only several months ago.

Early investigations have suggested, however that Vitamin D deficiency appears to be a very important risk factor for severe COVID-19 infection. A paper reported severity of COVID-19 infections with respect to 25(OH)D concentration in three Asian countries. Out of 49 patients with mild symptoms, 47 had serum 25(OH)D concentrations of >30 ng/mL compared with only four of 59 with ordinary symptoms, two of 56 severe patients, and two of 48 critical patients. The mean serum 25(OH)D concentrations for mild, ordinary, severe, and critical patients were 31, 27, 21, and 17 ng/mL, respectively. (4)

To reduce the risk of infection, it is recommended that people consider taking 10,000 IU/d of vitamin D3 for a few weeks to rapidly raise 25(OH)D concentrations, followed by 5000 IU/d. The goal should be to raise 25(OH)D concentrations above 40-60 ng/mL (100-150 nmol/L). For treatment of people who become infected with COVID-19, higher vitamin D3 doses might be useful. (5)

People with chronic disease generally have low 25(OH)D concentrations. It is also now well-recognized that Blacks have much higher COVID-19 infection and mortality rates. (6)

Based on the National Health and Nutrition Examination Survey (NHANES) 2001–2010, the prevalence of serum 25(OH)D concentrations <20 ng/mL was 72% for non-Hispanic blacks (NHBs), 43% for Hispanics, and 19% for non-Hispanic whites, with the prevalence of <10 ng/mL being 17% in NHBs. (7) Of all the risk factors Blacks have for becoming infected with COVID-19, raising serum 25(OH)D concentrations is the easiest one to address.


All drugs and supplements may have adverse side effects. If high-dose vitamin D3 is considered a drug, it differs from pharmaceutical drugs in that it has many side benefits.  There is mounting evidence that vitamin D3 can reduce the risk and severity of respiratory tract infections and COVID-19.  The mechanisms are known, there are many health benefits of higher 25(OH)D concentrations, and there are very few adverse effects of vitamin D3 supplementation. Vitamin D3 has demonstrated effectiveness in reducing the risk of overall cancer incidence and death, as well as the risk of progressing from pre-diabetes to diabetes. Thus, there is much to gain and little to lose by vitamin D3 supplementation now for COVID-19 prevention.

Further studies are required to better determine the threshold for protection against COVID-19 infection. Randomized controlled trials and large population studies are currently being conducted to evaluate these recommendations.


  1. World Health Organization (2020) Coronavirus disease (COVID-2019) situation reports. Geneva: World HealthOrganization. https://www.who.int/emergencies/diseases/novel-coronavirus-2019/situation-reports/ (accessed October 20, 2020)
  2. Lips P, Cashman KD, Lamberg-Allardt C, et al. (2019) Current vitamin D status in European and Middle East countries and strategies to prevent vitamin D deficiency: a position statement of the European Calcified Tissue Society. Eur J Endocrinol 180, P23–P54.
  3. Schleicher RL, Sternberg MR, Looker AC, et al. (2016) National estimates of serum total 25-hydroxyvitamin D and metabolite concentrations measured by liquid chromatography-tandem mass spectrometry in the US population during 2007–2010. J Nutr 146, 1051–1061.
  4. Alipio M.M. Vitamin D Supplementation Could Possibly Improve Clinical Outcomes of Patients Infected with Coronavirus-2019 (COVID-2019) SSRN Electron. J. 2020 Apr 9
  5. Grant WB, Lahore H, McDonnell SL, et al. Evidence that Vitamin D Supplementation Could Reduce Risk of Influenza and COVID-19 Infections and Deaths. Nutrients. 2020 Apr 2;12(4):988
  6. Garg S, Kim L, Whitaker M, et al. Hospitalization Rates and Characteristics of Patients Hospitalized with Laboratory-Confirmed Coronavirus Disease 2019—COVID-NET, 14 States, March 1–30, 2020. Morb. Mortal. Wkly. Rep. 2020;69:7
  7. Liu X, Baylin A, Levy PD. Vitamin D deficiency and insufficiency among US adults: Prevalence, predictors and clinical implications. Br. J. Nutr. 2018;119:928–936)

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