In earlier studies, some patient characteristics like heightened ACE2 expression, older age, Vitamin D deficiency, male gender, non-O blood group types, underlying comorbidities (diabetes, hypertension, cardiovascular disease, poorly controlled hypothyroidism, chronic obstructive pulmonary disease [COPD]), and host genetics are associated with a higher infection risk and/or worse outcome.[7]. Here, ACE2 is linked to vitamin D deficiency.