Emerging Understanding of Etiology and Epidemiology of the Novel Coronavirus (COVID-19) infection in Wuhan, China

Emerging Understanding of Etiology and Epidemiology of the Novel Coronavirus (COVID-19) infection in Wuhan, China Daibing Zhou, Peng Zhang , Chen Bao, Youzhi Zhang , Ning Zhu a, Department of Respiratory Medicine, Huashan Hospital, Fudan University, Shanghai, China. ⁎ Corresponding author: E-mail: zhangyouzhi@huashan.org.cn (Youzhi Zhang), zhuning@huashan.org.cn (Ning Zhu) Address: Huashan Hospital, Fudan University, No. 12, Urumqi Middle Road, Jing'an District, Shanghai 200040, P.R. China. # These authors contributed equally to this work.

contact, and aerosol can accelerate the transmission from person to person. However, it is not well known about the intermediator and other approaches. Identifying and characterizing the origin and host(s) of COVID-19 can help us to evaluate the potential risk of COVID-19 for transmission among humans or cross-species.

Introduction
It have been reported cases of a novel coronavirus

Etiology
Coronaviruses were first identified in the late sixties and well-known as a general pathology in a large portion of the common cold and other respiratory tract infections [3]. Coronaviruses, a member of the enveloped, single-stranded positive-sense RNA scientists realized that they were highly pathogenic to humans and could cause an outbreak.
The COVID-19 in Wuhan belongs to the genera-betacoronavirus, is enveloped with round or spherical particles at 60 -140nm in diameter and exerts a typical genetic structure of coronavirus (Guidance of COVID-19 infected-pneumonia (revised version 5)). Genome analysis notarizes that the COVID-19 is more closely related to bat-SARS-like (SL)-ZC45 and bat-SL-ZXC21 [6]. A study demonstrated the close identity between COVID-19 and two bat-SARS-like CoV (bat-SL-CoV ZC45 and bat-SL-CoV ZXC21), especially the sequence identities of E gene in bat-SL-CoV ZC45 being 98.7% among 13 gene region [10]. By analysis of data collected from the early outbreak, the COVID-19 sequence shared a 79.5% sequence identify to SARS-CoV through full-length genome analysis ， they stated synchronously that compared with SARS-CoV and MERS-CoV gene, COVID-19 had a longer spike protein and a different relative phylogeny of the complete RNA-dependent RNA polymerase gene as well as apparent genetics distance by Sequence and Phylogenetic analysis [11]. These results indicated that COVID-19 is a new betacoronavirus, not the SARS-CoV rumors reported in recently [10].

The host
Although a swift measure of isolation and disinfection by the government was  [16]. Sequentially, we should identify and isolate viral strains from COVID-19 infected animals to confirm the host(s) already. infected pneumonia, who had traveled to visit family in Wuhan [17]. They detected highly positive nucleic acid of COVID-19 in patients. Chinese scientists also collected patients' feces, they detected positive COVID-19 in 6.5% (4/62) of patients [12].

The route of transmission
Although they found the presence of viral nucleic acid in these patients, further studies would be needed to explore the existence of viral particles and nucleic acid levels in patients to demonstrate the fecal-oral transmission.
Fomite transmission, namely the spread of a virus through an object -door handle, door-bell, respirators, also plays a vital role in spreading the virus [18]. As for now, Nanshan Zhong and his group believed cases were infected with COVID-19 potentially through the fomite transmission from human to human, in addition to respiratory droplets and direct contact [12]. We need more clinical data to confirm the rationality. For the moment at least, we should have a good habit of washing hands and wearing disposable gloves.
It was widely concerned that a 30-hours old baby was diagnosed with COVID-19 pneumonia by the transfer of mother to child at a hospital in Wuhan babies and collected their liquid (including cord blood, breast milk, amniotic fluid, and throat swab) from their mothers in third trimester retrospectively, but they did not detect positive COVID-19 [19]. However, the authors also noted that the negative

Conclusion
At present, it is still severe about the spread of COVID-19 infection. The NHC officials have confirmed that respiratory droplets and contact transmission are the main disseminators. The carrier of aerosol may play an essential role in the spread of 9 COVID-19. The transfer of digestible approach and vertical propagation remain to be further determined. We should have a good habit of wearing masks and washing hands to reduce the risk of COVID-19 infection.

Conflicts of interest
The authors declare no competing interests.