ACE and COVID-19: Studies have found a significant association between 25(OH)D concentration and COVID-19 severity and mortality.[23] Studies have shown that the severe acute respiratory syndrome coronavirus (SARS-CoV)-2 infects and activates macrophages through angiotensin-converting enzyme (ACE) 2 receptors, leading them to secrete less interferon and more cytokines and chemokines, including IL-1β and IL-6.