Vitamin D in COVID - 19: Dousing the fire or averting the storm? – A perspective from the Asia-Pacific

Abstract

COVID-19, the acute respiratory tract infection (RTI) caused by the Coronavirus, Sars-CoV-2, has swept around the world. No country has been spared from its onslaught. Treatments that can reduce the risk of infection and mortality from the disease are desperately needed. Though high quality randomized controlled trials are lacking, some observational and interventional studies that explore the link between vitamin D and RTIs exist. Vitamin D modulates both innate as well as adaptive immunity and may potentially prevent or mitigate the complications associated with RTIs. Evidence linking vitamin D to COVID-19 include that the outbreak occurred in winter in the northern hemisphere at a time when vitamin D levels are lowest in resident populations, that blacks and minority ethnic individuals who are known to have lower levels of vitamin D appear to be disproportionately affected and have more severe complications from the disease, that vitamin D deficiency has been shown to contribute to acute respiratory distress syndrome and that case fatality rates increase with age and in populations with comorbid conditions such as diabetes, hypertension, and cardiovascular disease, all of which are associated with lower vitamin D levels. This narrative review summarizes the current knowledge about the epidemiology and pathophysiology of COVID-19, the evidence linking vitamin D and RTIs, especially COVID-19, the mechanistic reasons behind the possible protective effect of vitamin D in COVID-19, and the evidence with regard to vitamin D supplementation in RTIs. It concludes with some recommendations regarding supplementation of vitamin D in patients with COVID-19.

The Impact of Vitamin D Level on COVID-19 Infection: Systematic Review and Meta-Analysis

“…This review showed that improving vitamin D status in the general population has a potential benefit in reducing the risk of acquiring COVID-19 infection. Evidence by Chandran et al also recommends supplementation of vitamin D in patients with COVID-19 ( 36 ). A meta-analysis of randomized controlled trials (RCTs) concluded that the use of vitamin D supplements was associated with lower mortality in adults ( 37 ).…”

Vitamin D Deficiency and Low Serum Calcium as Predictors of Poor Prognosis in Patients with Severe COVID-19

“…On the other side, and through its anti-inflammatory actions, vitamin D acts as a key factor in the regulation of the adaptive immunity as it can suppress the responses induced by the T helper cell type 1 (Th1) and thus contributes to the attenuation of the cytokine storm particularly that of interleukin 6 (IL6). The latter is considered as the trigger of the systemic extension of inflammatory response, and of numerous acute complications, particularly pulmonary ones, observed in severely affected COVID-19 patients ( 3 , 9 ).…”

“…On the basis of the above mentioned arguments, several studies have been designed with the aim to explore that association. Although the findings are very heterogeneous and inconsistent, most of the observational studies agreed on a strong and significant association between vitamin D deficiency and the risk of both upper and lower respiratory tract infections ( 3 , 9 ). There is even some research demonstrating that adequate vitamin D levels correlate with a better prognosis in a number of respiratory infections such as those caused by Mycobacterium tuberculosis and the common influenza virus ( 9 ).…”

“…Vitamin D is a secosteroid with a hormonal function; its synthesis, from cholesterol, starts in the epidermis under the effect of the sun's ultraviolet B (UVB) rays (7). In reality, the link between vitamin D and respiratory infections of all kinds -bacterial, viral, and fungal -has been raised far earlier than the COVID-19 era (8)(9)(10). The first assumptions date back to the early part of the previous century, when it has been noted that there was an inverse correlation between the amount of UVB solar irradiation and the mortality rate during the 1918-1919 influenza pandemic (4).…”

A narrative review on characterization of acute respiratory distress syndrome in COVID-19-infected lungs using artificial intelligence

“…These comorbidities play a vital role in segregating AI models that can be independently trained for effective diagnosis and COVID-19 severity prediction. The selected comorbidity studies [ 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 ] were taken from https://pubmed.ncbi.nlm.nih.gov/ . Figure 5 shows the number of subjects with comorbidities enrolled in the ARDS-based studies.…”