Inclusion of Calcifediol in the Hospital Therapeutic Protocol for Treatment of SARS-CoV-2 Disease (COVID-19). Mortality Analysis. Retrospective Study.

The coronavirus disease-19 (COVID-19) pandemic, caused by the severe acute respiratory syndrome β-coronavirus (SARS-CoV-2), is one of the greatest challenges facing modern medicine and public health systems worldwide. Since its appearance in December 2019, it has caused nearly 7 million deaths, recognized, and confirmed worldwide, with high acute and post-acute morbidity, making it one of the deadliest in human history, with a devastating impact on national economies worldwide.

In the first outbreaks of COVID-19, although 80% were asymptomatic or had mild symptoms, 20% of patients developed severe symptoms, and 5% presented acute respiratory distress syndrome (ARDS), septic shock and accompanied multi-organ organ failure, with a high risk of death. Numerous risk factors have been described that influence the poor outcome of these patients, such as age, sex, high blood pressure, chronic obstructive pulmonary disease, diabetes, obesity, chronic lung and digestive diseases, asthma, chronic heart disease, cancer, D-dimer greater than 1000, or a high SOFA (Sequential Organ Failure Assessment Score). It has also been observed that patients with no a priori risk factors may have a poor outcome.

The scientific community immediately proposed strong social containment measures, quickly developed effective vaccines to prevent the appearance of severe clinical forms of COVID-19, and developed new treatments against all aspects of the disease: antiviral agents, anti-inflammatory agents, antithrombotic therapies, therapies against hypoxemic acute respiratory failure, therapies with anti-SARS-CoV-2 antibodies (neutralizing), modulators of the renin-angiotensin-aldosterone system and vitamins, so that social and economic activity has gradually recovered worldwide.

However, at the current time, there are some indications that hospital admissions for COVID-19 are on the rise again, so the pandemic seems far from over and future waves of infection are likely. These indications update and highlight again the repositioning strategy used since the beginning of the pandemic for the use of safe drugs, approved for another indication, and redirected to improve symptoms and clinical outcomes in patients with COVID-19. Various drugs have been investigated under this strategy and many studies have been published, some of them successful.

In this sense, during the first months of the pandemic, on the basis of biological plausibility, the investigators thought that the activation of the vitamin D receptor (VDR) signaling pathway of the vitamin D endocrine system (VDES) could produce beneficial effects in COVID-19. These effects were achieved by improving innate antiviral effector mechanisms, facilitating the induction of antimicrobial peptides/autophagy, mitigating the subsequent reactive hyperinflammatory phase of the host, decreasing the cytokine/chemokine storm, modulating the expression of the renin angiotensin system (RAAS) and neutrophil activity, maintaining the integrity of the pulmonary/intestinal epithelial barrier, stimulating epithelial repair and directly and indirectly reducing the increase in coagulability and prothrombotic tendency associated with a severe course of COVID-19 and its complications. Available evidence suggests that VDES/VDR stimulation, while maintaining optimal serum 25-hydroxyvitamin D [(25(OH)D)] status, in patients with SARS-CoV-2 infection may significantly reduce the risk of distress syndrome, acute respiratory distress syndrome (ARDS) and the development of severe COVID-19.