Study aim: Determination of the effect of vitamin A on respiratory sign and hospitalization duration inn patients with covid19 Design: two arm, parallel group randomized controlled trial Settings and conduct: This study will be conducted in Imam Reza hospital, affiliated with Tabriz University of medical sciences. based on inclusion criteria 30 patients will be selected and respiratory signs and saturation rate will be recorded at the first day of hospitalization. then he patients will randomly divided to two groups of 15 patients. in vitamin A group, the patients will receive 50000 dose of vitamin A along with routine treatments and in the control group, The patients will receive only the routine treatments. after two weeks the respiratory sing, saturation rate and hospitalization days will be recorded Participants/Inclusion and exclusion criteria: Inclusion criteria: confirmed diagnosis of COVID19 with RT-PCR; hospitalized patients; ventilator independent patients; Exclusion criteria: being pregnant; lactating mothers; not consent to participate in the study; using high-dose vitamin A in last month. Intervention groups: Vitamin A group will be include 15 patients with COVID19 that will be treated with vitamin A 50000 along with routine treatment for two weeks Control group will also include 15 patients with COVID19 that will be treated with only routine treatment for two weeks Main outcome variables: Hospitalization duration respiratory signs