ABSTRACT
Background: An outbreak of pneumonia associated with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in Wuhan city and then spread to other cities. It is very urgent to delineate the epidemiological and clinical characteristics of these affected patients. Methods: To investigate the epidemiological characteristics of the COVID-19, we describe a case series of 473 patients with confirmed COVID-19 in Wenzhou of China from January 27 to March 2, 2020.Results: The median age of all patients was 47.6 years, 48.4% of which were female. 33.8% of the patients had a history of residence in Wuhan. Fever (71.7%) and cough (43.1%) were the most common symptoms. In addition, three kinds of unconventional cases were observed, namely 4.9% asymptomatic patients, 7.6% confirmed patients who had no link to Wuhan city but contact with individuals from Wuhan without any symptoms at the time of contact, and 12.9% confirmed patients who had an unknown source of transmission. We estimated that the basic reproductive number (R0) was 2.75 (95%CI: 2.37-3.23). The effective reproduction number (Rt) fluctuated within the range of 2.50 to 3.74 from January 11 to January 16 while gradually reached the peak of 3.74 on January 16. Rt gradually decreased after January 16 and decreased to 1.00 on January 30. Rt continually decreased and reached the lowest point (0.03) on February 21, 2020.Conclusion: Our findings presented the possibility of asymptomatic carriers affected with SARS-CoV-2, and this phenomenon suggested that chances of uncontrollable transmission in the larger population might be higher than formerly estimated, and transmission by these three kinds of unconventional patients in Wenzhou may be an important characteristic of infection in other mid-sized cities in the world. This study evaluated the epidemic characteristics of Wenzhou after having cases imported from Hubei Province and the effects after adopting a series of strict prevention and control strategy.