Study aim: Determining the effect of vitamin A, B, C, D, and E supplementations on inflammatory and biochemical markers in critically ill patients with COVID-19 Design: Randomized clinical trial study,triple-blind trial,135 critical ill COVID-19 patients undergoing respiratory & nutritional supports,Intervention & control groups via web-based randomization by https://www.randomizer.org,45 patients as intervention group and other 90 as control group Settings and conduct: Attending at ICU of Razi hospital in Rasht, Iran and complete the consent form, information will be required using these questionnaires:Medical history, Anthropometric measurement, Dietary intake, Biochemical & inflammatory indices(baseline & after 20 days) Participants/Inclusion and exclusion criteria: Inclusion criteria: ICU patient of Razi hospital in Rasht; with Covid-19 diagnosis; under respiratory and intestinal nutrition support; written consent; age> 34-y; diagnosis of COVID-19 based on relevant symptoms; GCS score at least 3. Exclusion criteria: Not tendency to participate; having diseases that disrupt the study process; malignant tumors; recent chemotherapy drugs use; taking any of vitamin supplements during 3-month prior to study, history of allergy to vitamins, pregnancy. Intervention groups: Intervention group will be received vitamin A, B, C, D, and E supplementations including vitamin A(50,000 dose/week), B complex(10 mg vitamin B1, 4 mg vitamin B2, 4 mg vitamin B6, 40 mg nicotinamide & 6 mg dexpanthenol/day), C(500 mg/day), D(50,000 dose/day) and E(100 mg/day) from HAKIM Vitakim Pharmaceutical Company for 20-day by intestinal formula in gavage form.Specific intervention or activity don’t perform in the control group and only intake same calorie & route with intervention group Main outcome variables: WBC,Neutrophils,Lymphocytes,LDH,CPK,CBC,CRP,PO2,PCO2