Characteristics of the studied patients
As shown in Figure 1, of all 490 patients reported as of January 12th in a city of China, 31(6.3%) patients were excluded due to the complete information (including clinical outcomes and symptoms) of them were not published in time for the day, because the complete information collection and organization needs a certain amount of time, and 459(93.7%) patients had completed characteristics and were described in Table 1. The median age was 48 years (IQR, 37-56; range, 2-93 years), and 215 (46.8%) were females. The median time from onset to diagnosis was 6.0 days (range: 0-23 days). Of these patients, 42(9.2%) were severe patients and 417(90.8%) were non-severe patients. Fever (72.1%) and cough (43.6%) were the most common symptoms, whereas diarrhea or castalgia (3.3%) were rare. 172 (37.5%) patients had a history of travel or residence to Wuhan. No deaths occurred in the total patients.
New features of SARS-CoV-2 in WZ differing from Wuhan
The point worth noting about this novel coronavirus pneumonia in WZ city, was that the emergence of three kinds of unconventional cases. As shown in Table 1 and Figure 2, there were 20 asymptomatic carriers accounted for 4.4% of the total patients, 36 (7.8%) patients who had no link to Wuhan city but contact with individuals from Wuhan without any symptoms at the time of contact and 49 (10.7%) patients who had no link to Wuhan city nor a history of intimate contact with patients or individuals from Wuhan without any symptoms, which suggests that asymptomatic carriers were also likely to transmit the virus. We divided all patients into two groups, one with a history of residence and travel in Wuhan and one without, and then made a time distribution chart based on the time of onset of diseases. As indicated in Figure 3, in addition to the change in daily number of new cases with a history of residence and travel in Wuhan, we can see the change of daily number of new cases with no link to Wuhan. There were 287 cases who had no link to initial epidemic area accounted for 62.5% of 459 cases and 172 cases had links to initial epidemic area accounted for 37.5%. It was five days that between the peak of daily number of new cases who have no link to initial epidemic area and who have link to initial epidemic area. On January 23, initial epidemic city was on lockdown by government of China so that the daily number of new cases who had link to initial epidemic area decreased gradually. And on the same day, Zhejiang Province activated first-level public health emergency response so that the daily number of new cases who had no link to initial epidemic area begun to decreased gradually after three days. All these evidences indicated that the epidemic situation in this city of China might potentially shift from the import stage to the community spread stage in the coming time period. However, the slowdown of the increase rate of new patients, also indicated that the measures and strategies of prevention and control in this city have proven effective. (Figure 1).
An outbreak of infection in a public place
Moreover, there was an outbreak of infection in a public place at the Yintai world trade center (Figure 4). On January 20, a 39-year-old saleswoman went to local hospital for treatment by herself after breaking out with a fever at 38.5° C, accompanied with chills, dizziness and headache, and symptoms of soreness and fatigue. She was subsequently diagnosed COVID-19 on January 28, but the source of which is unknown. As of the date of publication, a total of 16 additional patients resulting from this mall have been confirmed, namely two staff members, two sales persons, one janitor, nine customers, and two individuals outside the mall but close contact with one of the above.