Back to basics: review on vitamin D and respiratory viral infections including COVID-19

Abstract

Importance As the scientific community is in a marathon in finding out the cure for COVID-19, in this crisis, it is essential for the physicians not to forget about the basics. Due to the pandemic crisis, in many nursing homes and hospitals, there established new policies on decreasing unnecessary medications to minimize cross-contamination. Sometimes these policies are making providers avoid essential drugs such as Vitamins, including Vitamin D. In this paper, we try to emphasize the importance of Vitamin D in COVID-19 and respiratory viral patients. Relevance Vitamin D helps in decreasing the ‘pro-inflammatory cytokines’ in the lungs and acts in immunomodulatory function, and ‘also it will increase the anti-inflammatory, antiviral responses of the respiratory epithelial cells during infection.’ Conclusion Due to the highly contagious nature of COVID-19 and the increased morbidity and mortality with no appropriate therapy and vaccine, one must be cautious and do everything to help COVID-19 patients. In hospitals and other health care settings to decrease cross-contamination, holding other non-essential medications is taking place. Discontinuing Vitamins could increase the mortality and morbidity of those affected, especially in deficient/insufficient individuals. Obtaining serum 25 (OH) D levels in all patients with viral respiratory infections, especially COVID-19, could help in the detection and treatment of Vitamin D deficiency and potentially decrease recovery time and improve outcome. Even though evidence suggests that vitamin D has the anti-inflammatory, antiviral properties, randomized double-blinded controlled trials are needed to verify this further, and to understand Vitamin D and COVID-19 better. Abbreviations Vitamin D receptor-VDR; 25(OH)D- 25 hydroxyvitamin D; 1,25 (OH)D-1,25 dihydroxy Vitamin D; 1α,25-dihydroxy Vitamin D-1,25[OH] 2 D or calcitriol; IU- International Units; Interferons stimulated genes- ISG; ARI- acute respiratory infection; RSV- respiratory syncytial virus; RTI- Respiratory tract infections; COPD-Chronic obstructive pulmonary disease; BMI-Basal metabolic index; USA-USA.

Immunological Aspects of SARS-CoV-2 Infection and the Putative Beneficial Role of Vitamin-D

“…The adaptive immune system is initiated by the activation of antigen-presenting cells, such as dendritic cells and macrophages, which in turn activate the antigen-recognizing cells, T lymphocytes and B lymphocytes, which are major determinants of the immune response [ 86 ]. 1α,25-Dihydroxyvitamin D directly modulates inflammatory cytokines that are dependent on NF-κB activity in numerous types of cells, including macrophages, by blocking NF-κB p65 activation via the upregulation of the NF-κB inhibitory protein IκBα [ 87 ].…”

“…TLR3 recognizes viral double-stranded RNA or synthetic double-stranded RNA (polyinosinic: polycytidylic acid) and is primarily involved in viral defense. Vitamin D treatment has been demonstrated to attenuate the expression of IL-8 in respiratory epithelial cells by double-stranded RNA-TLR3 [ 86 , 88 ].…”

Bronchiectasis—Could Immunonutrition Have a Role to Play in Future Management?

“…Vitamin D receptors are further present on T-cells, B-cells and monocytes ( 26 ). As well as possessing immunomodulatory functions, vitamin D is also known to increase the antiviral responses of respiratory epithelial cells during infections ( 27 ). Vitamin D has been found to enhance neutrophil killing in patients with bacterial respiratory tract infections (RTIs) and to lower pro-inflammatory cytokine production induced by infected neutrophils ( 28 ).…”

COVID-19-Induced Vestibular Neuritis, Hemi-Facial Spasms and Raynaud's Phenomenon: A Case Report

“…As of September 21, 2020, nearly 31.1 million cases and 962,000 deaths were reported in 213 countries and territories. Severe acute respiratory syndrome CoV (SARS-CoV) and novel CoV were believed to share the same receptor, angiotensin-converting enzyme (ACE), hence the virus was termed SARS-CoV-2, and World Health Organization named the disease as coronavirus disease 2019 (COVID-19) in February 2020 and declared it as a pandemic on March 11, 2020 [ 1 ].…”

“…Initially, fever, cough, shortness of breath, and myalgia were reported as common symptoms and pneumonia-like features in chest computerized tomography (CT) scan in patients affected by COVID-19 [ 1 ]. But, later, various neurological manifestations were noticed.…”