Vitamin D supplementation to prevent COVID-19 in patients with COPD: a research perspective.

There is increased evidence that the massive release of pro-inflammatory cytokines leading to the cytokine storm syndrome shapes the evolution of COVID-19 and is responsible of the severity of COVID-19 in some patients. A recent review argued that vitamin D deficiency could have increased the COVID-19 outbreak and suggested vitamin D supplementation as a preventive action. In fact, many factors seem to be correlated both to low vitamin D levels and the importance of COVID-19 spreading and severity. It is also important to highlight that the lockdown, implemented in many countries, prevents people to go out and then increases the risk of vitamin D deficiency. COPD patients are particularly at risk to have low levels of vitamin D due to multiple risk factors. COPD may generate a systemic inflammatory process responsible of secondary extra-pulmonary impairments. Vitamin D deficiency could sustain and aggravate the systemic inflammation associated to COPD. Reports have also shown that vitamin D deficiency was associated to exacerbations and hospital admissions, as well as lung function. Recent research showed that vitamin D supplementation significantly reduced COPD exacerbations. Although vitamin D deficiency was not proved to be neither a risk factor of COVID-19, nor a determinant of its severity, vitamin D supplementation represents a preventive perspective that needs to be further studied.