Since the initial report of coronavirus disease (COVID-19) from the City of Wuhan, China in December 2019, there have been multiple cases globally. Reported here are 11 cases of COVID-19 at this hospital; all of the patients in question presented with relative bradycardia. The severity of the disease was classified into four grades. Of the patients studied, 3 with mild COVID-19 and 3 with moderate COVID-19 improved spontaneously. Lopinavir/ritonavir was administered to 3 patients with severe COVID-19 and 2 with critical COVID-19. Both patients with critical COVID-19 required mechanical ventilation and extracorporeal membrane oxygenation. Both patients with critical COVID-19 had a higher fever that persisted for longer than patients with milder COVID-19. The respiratory status of patients with critical COVID-19 worsened rapidly 7 days after the onset of symptoms. Relative bradycardia may be useful in distinguishing between COVID-19 and bacterial community-acquired pneumonia. In patients who have had a fever for > 7 days, the condition might worsen suddenly.