BACKGROUND: The case fatality rate of coronavirus disease 2019 (COVID-19) is estimated to be between 4.3% and 11.0%. Currently there is no effective antiviral treatment for COVID-19. Thus, early recognition of patients at high risk is important. METHODS: We performed a retrospective observational study of 110 patients with severe acute respiratory syndrome coronavirus 2 infection. We compared the effectiveness of three scoring systems: the Systemic Inflammatory Response Syndrome (SIRS), quick Sequential Organ Failure Assessment (qSOFA), and National Early Warning Score (NEWS) systems, for predicting the prognosis of COVID-19. The area under the receiver operating characteristic curve (AUROC) was used for these assessments, and Kaplan-Meier survival curves were used to identify the cumulative risk for 28-day mortality according to the NEWS stratification. RESULTS: For predicting 28-day mortality, NEWS was superior to qSOFA (AUROC, 0.867 vs. 0.779, P < 0.001), while there was no significant difference between NEWS and SIRS (AUROC, 0.867 vs. 0.639, P = 0.100). For predicting critical outcomes, NEWS was superior to both SIRS (AUROC, 0.918 vs. 0.744, P = 0.032) and qSOFA (AUROC, 0.918 vs. 0.760, P = 0.012). Survival time was significantly shorter for patients with NEWS >/= 7 than for patients with NEWS < 7. CONCLUSION: Calculation of the NEWS at the time of hospital admission can predict critical outcomes in patients with COVID-19. Early intervention for high-risk patients can thereby improve clinical outcomes in COVID-19 patients.