The researchers found that 80 per cent of the 216 patients infected with COVID-19 had vitamin D deficiency, and that men had lower vitamin D levels than women. A study of over 200 COVID-19 cases in a hospital in Spain found that about 80 per cent patients had vitamin D deficiency, scientists said. However, the study published in the Journal of Clinical Endocrinology & Metabolism, did not find any relationship between vitamin D concentrations or vitamin deficiency and the severity of the disease. The study also found that people who had both COVID-19 and lower vitamin D levels also had a higher number of inflammatory markers such as ferritin and D-dimer, which have been linked to poor COVID-19 outcomes. A different study found that COVID-19 patients who had adequate vitamin D levels had a 51.5 percent lower risk of dying from the disease and a significant reduced risk for complications. Medical experts theorize that maintaining adequate vitamin D levels may help lower risk or aid recovery from severe COVID-19 for some people, though more testing is needed. One approach is to identify and treat vitamin D deficiency, especially in high-risk individuals such as the elderly, patients with comorbidities, and nursing home residents, who are the main target population for the COVID-19.