“…Table A describes the characteristics of the 31 included observational studies ordered by outcome severity [ [44] , [45] , [46] , [47] , [48] , [49] , [50] , [51] , [52] , [53] , [54] , [55] , [56] , [57] , [58] , [59] , [60] , [61] , [62] , [63] , [64] , [65] , [66] , [67] , [68] , [69] , [70] , [71] , [72] , [73] , [74] ]. These studies reported on mortality from COVID-19 ( n = 20), ICU admission ( n = 5), length of ICU stay ( n = 1), invasive ventilation ( n = 7), non-invasive ventilation ( n = 4), hospitalization ( n = 3), length of hospital stay (n = 5), disease severity ( n = 12), pneumonia (n = 1), multi-organ damage (n = 1), acute kidney injury (n = 1), ARDS (n = 5), SARS-CoV-2 positivity (n = 4), and 25(OH)D levels ( n = 7).…”