Human infection with the novel avian-origin influenza A (H7N9) virus has aroused global concern. In this report, the clinical characteristics of 111 laboratory-confirmed cases in China are presented. On March 30, 2013, three patients with fatal cases of rapid, progressive pneumonia were confirmed to be infected with a novel avian-origin influenza A (H7N9) virus that had not been detected in humans and animals previously. 1 , 2 The new human H7N9 viruses are the product of reassortment of viruses that are of avian origin. Global attention was soon focused on the situation because of the increasing number of new cases and the high rate of death associated with these infections. 3 As of May 9, the World Health Organization (WHO) had reported 131 laboratory-confirmed cases, including 32 deaths. 4 However, data on . . .