Inclusion Criteria:  Adult ≥ 18 years of age at the time of inclusion in the study; Recently hospitalized patients in whom SARS CoV-2 infection has been laboratory confirmed by RT-PCR or other commercial or public health test on any sample. Severity of 3-4-5 according to the WHO 7-point ordinal scale (3: hospitalized, no oxygen therapy; 4: hospitalized, oxygen by mask or nasal prongs; 5:non-invasive ventilation or high-flow oxygen); Subject (or authorized legal representative) who can provide oral or written informed consent before beginning any study procedure; Understand and agree to abide by the study procedures.  Exclusion Criteria:  Contra-indication to NASAFYTOL® or constituents (incl. Vit D): hypersensitivity or allergy to product components; Swallowing disorder or inability to take oral caps; Presence of comorbidities that imply a poor prognosis (according to clinical judgment); Pregnancy or breastfeeding women; If patient is a female of childbearing potential, patient must use an effective means of birth control (oral, intravaginal or transdermal oestrogen-progestogen combined hormonal contraceptives or intrauterine devices or sexual abstinence); Serious or active bacterial infections or documented sepsis by pathogens other than SARS-CoV-2; Patients participating in clinical trials of other products; Patients presenting acute impairment of renal function or nephrolithiasis; ALT/AST> 5 times the normal limit, or Neutropenia (Absolute neutrophil count < 500/uL), or Thrombocytopenia (Platelets < 50,000/uL).