In the current study with a total of 459 patients with COVID-19 in a city of China, we found that there were the emergence of three kinds of unconventional patients including 4.4% cases with asymptomatic, 7.8% patients who had no link to Wuhan but contact with individuals from Wuhan without any symptoms at the time of contact, and 10.7% cases who had no known direct source of transmission, indicated that the COVID-19 presence and prevalence may be underestimated at present，increasing the difficulty of prevention and control.
Along with the epidemic of SARS-CoV-2 spreads rapidly throughout China and worldwide, more concerns and new strategies should be undertaken in the next a few days. It is untoward to differentiate and screen patients with atypical symptoms, and the rapid human-to-human transmission among close contacts is a crucial peculiarity for SARS-CoV-2[7, 17]. A recent study indicated that WZ had become the city with the most patients of SARS-CoV-2 outside of Wuhan in China. In addition, previous studies had reported that asymptomatic transmission of SARS-CoV-2 infection through close contacts in both familial and hospital settings had been observed. Also, clustered outbreaks caused by asymptomatic individuals were reported. Based the fact that the SARS-CoV-2 virus can be positively detected in asymptomatic patients, we could reasonably speculate that these asymptomatic patients may carry a certain amount of active virus in the body and might pollute the surrounding environment, and thus became a potentially threatening source of SARS-CoV-2 infection. In this study, we found a emergence of unconventional patients with COVID-19, and this phenomenon suggested that chances of uncontrollable transmission in the larger population might be higher than formerly estimated, and asymptomatic transmission may be one of the characteristics of infection in other area. There were likely to three aspects of source infection, indirect transmission, aerosol transmission and fecal‐oral transmission.
The indirect transmission of the causative virus occurred, mayble resulting from virus contamination of surfaces of objects. The Guangzhou Center for Disease Control and Prevention detected the nucleic acid of SARS-CoV-2 on a doorknob at a patient’s house . Researchers have detected SARS-CoV-2 on surfaces of objects in a symptomatic patient’s room and toilet area. Guo, et.al tested surface and air samples from an intensive care unit (ICU) and a general COVID-19 ward (GW) at Huoshenshan Hospital in Wuhan, China. The surface of objects positive results were concentrated in the contaminated areas ICU or GW for floor swab samples, the floor of the pharmacy, the floor of medical staff dressing room, half of the samples from the soles of the ICU medical staff shoes; there were positive results that were frequently touched by medical staff or patients for computer mice, sickbed handrails, doorknobs, patient masks, sleeve cuffs and gloves of medical staff. Hence, SARS-CoV-2 was widely distributed on object surfaces, implying a potentially high infection risk spread via fomites.
The aerosol to mean the small respirable particles <5-10µm that can remain airborne and are capable of short and long‐range transport. [23-25] Morawska, et.al studies that normal breathing and talking result in size distributions of droplets with the majority, 80-90%, in the <1 µm range. In the United States, the likelihood of an airborne aerosol form of active SARS‐CoV‐2 was the Skagit Valley Chorale rehearsal in Mount Vernon, Washington, that took place on March 10, implying the forceful breathing action of singing may have increased dispersion of the virus at the church. Tang et al found for SARS‐CoV‐1 that “particles of diameters 1-3 µm remained suspended almost indefinitely, 10 µm took 17 min, 20 µm took 4 min, and 100 µm took 10 seconds to fall to the floor”.  Pathogen‐bearing droplets are reported to travel up to 23-27 feet, with droplet size, turbulence, speed of the gas cloud, humidity, and temperature being important factors for the distance travelled. long‐range aerosol transport was implicated as the cause of the spread of the disease in several studies. For the aerosol and surface stability of virus, SARS-CoV-2 can remain viable and infectious in aerosols for hours and on surfaces up to days, so aerosol and contact transmission of the virus is reasonable. 
SARS-CoV and Middle East respiratory syndrome coronavirus (MERS-CoV), are known to cause respiratory and enteric symptoms. In the SARS outbreak of 2002-03, 16%-73% of patients with SARS had diarrhea during the course of the disease.  138 consecutive hospitalized patients with COVID-19, investigators reported that approximately 10% of patients initially presented with gastrointestinal symptoms, prior to the subsequent development of respiratory symptoms. Studies have identified the SARS‐CoV‐2 in anal/rectal swabs and stool specimens of COVID-19 patients, even after the clearance of the virus in the upper respiratory tract.[33-37] The viral receptor angiotensin converting enzyme 2 (ACE2) was found to be expressed in gastrointestinal epithelial cells. [38, 39] So that SARS‐CoV‐2 can actively infect and replicate in the gastrointestinal tract. Although there been no solid evidence to confirm that SARS‐CoV‐2 can be transmitted through the fecal‐oral route, this possibility exists as the virus has been successfully isolated in a stool or anal swab of patients with COVID‐19, which is almost as accurate as a pharyngeal swab.
The epidemic characteristics of SARS-CoV-2 in WZ may be typical of the outbreaks in other Chinese cities outside of Wuhan. Besides, since the outbreak of SARS-CoV-2 in a public place in WZ city occurred, this is a typical incidence of outbreak that should be of great concern.
The epidemic situation might potentially shift from the import stage to the community spread stage in the coming time period. Although the slowdown trends of the increase number of new patients in recent days, we need to find and control the infection source of patients affected with SARS-CoV-2[8, 40]. In light of the emergence of unconventional patients, and Diagnosis and Treatment of Pneumonitis Caused by New Coronavirus (trial version 5) published by China National Health Commission  indicated that asymptomatic infected individuals may also be the source of infection, and there were evidences that asymptomatic infections has a certain infectivity. Based on the above, it suggested that suspected patients should include patients with clinical symptoms and who, in the history of epidemiology, intimate contact with individuals from Wuhan, although these individuals from Wuhan are not confirmed cases and without any symptoms at the time of contact. So far, our understanding of the epidemic characteristics of SARS-CoV-2 is still insufficient, and we still need to track the development closely, further collect and analyze information through epidemiological investigations.
Our study had some obvious limitations. Firstly, the case information of WZ was extracted from the website of Wenzhou Health Commission, which were incomplete (38 cases) in the early stage of the epidemic. Secondly, it is necessary to dynamically observe for a period of time to determine whether without symptomatic patients is asymptomatic and pro-symptomatic. We did not have dynamic observation therefore we could not distinguish the asymptomatic and pro-symptomatic patients. Lastly, our study was based on case report data, which were more likely to report patients with severe or obvious symptoms resulted in the proportion of asymptomatic infections was underestimated.