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Rapid response to:


Preventing a covid-19 pandemic

BMJ 2020; 368 doi: (Published 28 February 2020) Cite this as: BMJ 2020;368:m810

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Rapid Response:

Covid 19, Vitamin D deficiency, Smoking, Age and Lack of Masks Equals the Perfect Storm

Dear Editor

Covid 19 was introduced to the northern hemisphere during the winter of 2019/2020. It is well known that vitamin D levels are significantly lower at the end of winter than in the summer. More than 40% of Canadians have low levels of vitamin D (less than 50nmol/l)[1] at this time of year. Solar radiation is a major contributor to vitamin D levels. Regions in China (Wuhan)[2](and Italy (northern areas)[3] and parts of Spain again have noticeably less solar radiation annually as well as more air pollution. These areas with high air pollution[4] block ultraviolet frequencies that result in vitamin D production in the skin[5] .
Vitamin D has a significant impact on our immune system[6] being important in barrier function maintaining tight junctions, gap junctions and adherens junctions. Recent evidence shows that vitamin D down regulates the DDP/CD26 binding site of the COVID-19 spike glycoprotein thus reducing the virulence of this virus.[7]. As well it is important for the production of cathelicidins and other antimicrobial compounds. Vitamin D also reduces the cytokine storm by reducing the expression of pro-inflammatory cytokines and improving anti inflammatory cytokines[8] such as LL 17, thus attenuating the risk of cascading responses in the immune system that may lead to death.
In order to correct the vitamin D winter low, rapid supplementation with 10,000IU of vitamin D3 can be safely employed as suggested in a most recent article[9]. Another approach would be the employ the” vitamin D hammer” as a one time 50,000IU dose of vitamin D3 when one becomes ill[10]. Of course this one time dose should be followed by a reasonable daily dose of at least 5000IU until vitamin D levels are at 100nmol/l.
Smoking reduces vitamin D levels[11], increases inflammation and slows resolution of viral infections[12]. Vitamin D may have a protective effect on lung function[13] and reduce infections of the lung in both adults and children[14].
Those that are older[15] have an increased likelihood of being vitamin D deficient and the skin with increasing age becomes less efficient at producing vitamin D[16]. Thus supplementation of vitamin D is more important as we age.
Wearing a mask has been shown to reduce infection in clinical situations and may be another protective measure[17]. A rational approach needs to be taken[18]. It appears as this pandemic is unfolding that countries that adopt wearing masks early on (even home made cloth masks) are faring much better than those that do not. Certainly wearing masks is not a panacea without all the other public health measures, but are useful for everyone within a population to wear when public as asymptomatic individuals can transmit this virus[19].
Modifiable risk factors for covid 19 infections would include discontinuing smoking, normalizing vitamin D levels quickly, and using universal mask protection.

1. Vitamin D levels of Canadians, 2012 to 2013 []
2. Ehsanul Kabira PK, Sandeep Kumarc, Adedeji A Adelodun, Ki-Hyun Kim: Solar energy: Potential and future prospects. Renewable and Sustainable Energy Reviews 2018, February, 82:894-900.
3. Annual solar radiation in Italy []
4. Additional Renewable Maps - Spain [
5. Hosseinpanah F, Pour SH, Heibatollahi M, Moghbel N, Asefzade S, Azizi F: The effects of air pollution on vitamin D status in healthy women: a cross sectional study. BMC Public Health 2010, 10:519.
6. Schwalfenberg GK: A review of the critical role of vitamin D in the functioning of the immune system and the clinical implications of vitamin D deficiency. Mol Nutr Food Res 2011, 55:96-108.
7. Mccartney DM, Bryne D.G.: Optimisation of Vitamin D Status for Enhanced Immuno-protection Against Covid-19. Irish Mediical Journal 2020, 113:58.
8. Svensson D, Nebel D, Nilsson BO: Vitamin D3 modulates the innate immune response through regulation of the hCAP-18/LL-37 gene expression and cytokine production. Inflamm Res 2016, 65:25-32.
9. Grant WBL, H.; McDonnell, S.L.; Baggerly, C.A.; French, C.B.; Aliano, J.L.; Bhattoa, H.P.: Evidence That Vitamin D Supplementation Could Reduce Risk of Influenza and COVID-19 Infections and Deaths. Nutrients 2020, 12.
10. Schwalfenberg G: Vitamin D for influenza. Can Fam Physician 2015, 61:507.
11. Brot C, Jorgensen NR, Sorensen OH: The influence of smoking on vitamin D status and calcium metabolism. Eur J Clin Nutr 1999, 53:920-926.
12. Gualano RC, Hansen MJ, Vlahos R, Jones JE, Park-Jones RA, Deliyannis G, Turner SJ, Duca KA, Anderson GP: Cigarette smoke worsens lung inflammation and impairs resolution of influenza infection in mice. Respir Res 2008, 9:53.
13. Lange NE, Sparrow D, Vokonas P, Litonjua AA: Vitamin D deficiency, smoking, and lung function in the Normative Aging Study. Am J Respir Crit Care Med 2012, 186:616-621.
14. Martineau AR, Jolliffe DA, Hooper RL, Greenberg L, Aloia JF, Bergman P, Dubnov-Raz G, Esposito S, Ganmaa D, Ginde AA, et al: Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ 2017, 356:i6583.
15. Gallagher JC: Vitamin D and aging. Endocrinol Metab Clin North Am 2013, 42:319-332.
16. Boucher BJ: The problems of vitamin d insufficiency in older people. Aging Dis 2012, 3:313-329.
17. Sung AD, Sung JAM, Thomas S, Hyslop T, Gasparetto C, Long G, Rizzieri D, Sullivan KM, Corbet K, Broadwater G, et al: Universal Mask Usage for Reduction of Respiratory Viral Infections After Stem Cell Transplant: A Prospective Trial. Clin Infect Dis 2016, 63:999-1006.
18. Shuo Feng CS, Nan Xia, Wei Song, Mengzhen Fan, Benjamin J Cowling: Rational use of face masks in the COVID-19 pandemic. wwwthelancetcom/respiratory March 20,2020.
19. Klompas M, Morris CA, Sinclair J, Pearson M, Shenoy ES: Universal Masking in Hospitals in the Covid-19 Era. N Engl J Med 2020.

Competing interests: No competing interests

05 April 2020
Gerry K Schwalfenberg
Family Physician
University of Alberta
#301,9509-156 St