This cohort study regarding COVID-19 cases in Turkey reveals that older age, presence of comorbidity, bilateral infiltration on CT, high neutrophil/lymphocyte ratio, low monocyte and platelet count, elevated liver enzymes, low GFR, high levels of muscle enzymes, and high levels of ferritin and IL-6 on admission are predictors of SARI and severe disease. Here, IL6 is linked to COVID-19.