Prophylactic and therapeutic potential of vitamin D in asthma during the COVID-19 pandemic: the new hope?

Over the last two decades, the emergence of lethal virulent strains of coronavirus (CoV), including the severe acute respiratory syndrome CoV 2 (SARS-CoV-2), which is responsible for the coronavirus disease 2019 (COVID-19) pandemic, has become a matter of great attention to the scientific community. Despite the implementation of preventive measures throughout the world, the spread of this disease and associated co-morbidities and mortality continue in all countries, continents, and populations of all ages. COVID-19 is highly contagious. Clinical manifestations are diverse and range from asymptomatic, mild to severe, life-threatening complications in the elderly and patients with underlying conditions such as cardiovascular disease, diabetes, obesity, and asthma. In addition, viral infections can trigger asthma attacks. To date, there is no specific treatment schema to combat COVID-19 disease. Current patient care revolves around disease severity and supportive treatment of symptoms from home-rest in mild disease to anti-viral therapy, oxygen support, anti-inflammatories, and anti-coagulants in severe COVID-19. Regarding prevention, the World Health Organization recommends vaccination, social distancing, quarantine, the wearing of surgical masks, and handwashing. In many countries, vaccination is optional, and given that parents are often reluctant to vaccinate themselves and their children for fear of side effects, identifying ways to enhance or support the immune system to prevent infection or improve recovery in vulnerable populations is worth investigating. Furthermore, research has focused on the pharmacological management of COVID-19 symptoms and much less has been published on nutrition therapy. Therefore, the scope of this review is to summarize the latest evidence on the use of vitamin D to support the metabolism and the immune system of asthma patients during the COVID-19 pandemic. A brief overview of asthma and COVID-19 pathophysiology, COVID-19 treatment guidelines for asthma patients, and the role of vitamin D in lung health, including the optimal blood level required to enhance immunity, will be suggested.