Coronavirus disease 2019 (COVID-19) is an acute respiratory infection caused by SARS-CoV-2. To date (June 5, 2020), more than 6.5 million cases and 387,000 deaths have already been reported across the world. A current meta-analysis reported that the mortality rate across the world was 2.72%. Many factors influence the mortality rate of COVID-19. The Neutrophil-to-Lymphocyte Ratio (NLR) is an accessible, reproducible, and widely used biomarker for evaluating the prognosis of many diseases Recently, a study showed that Neutrophil-to-Lymphocyte Ratio (NLR) is elevated in patients with severe COVID-19 and the authors suggest that its performance in the prognosis of severe disease should be further evaluated.