New Insights of Emerging SARS-CoV-2: Epidemiology, Etiology, Clinical Features, Clinical Treatment, and Prevention

Abstract

Since the first reports that the novel coronavirus was showing human-to-human transmission characteristics and asymptomatic cases, the number of patients with associated pneumonia has continued to rise and the epidemic has grown. It now threatens the health and lives of people across the world. The governments of many countries have attached great importance to the prevention of SARS-CoV-2, via research into the etiology and epidemiology of this newly emerged disease. Clinical signs, treatment, and prevention characteristics of the novel coronavirus pneumonia have been receiving attention worldwide, especially from medical personnel. However, owing to the different experimental methods, sample sizes, sample sources, and research perspectives of various studies, results have been inconsistent, or relate to an isolated aspect of the virus or the disease it causes. Currently, systematic summary data on the novel coronavirus are limited. This review combines experimental and clinical evidence into a systematic analysis and summary of the current progress of research into SARS-CoV-2, from multiple perspectives, with the aim of gaining a better overall understanding of the disease. Our report provides important information for current clinicians, for the prevention and treatment of COVID-19 pneumonia.

Keywords: SARS-CoV-2; clinical features; clinical treatment and prevention; coronavirus; epidemiology; etiology.

Figure 1

The distribution of patients across world. (A) First reported date of case, by country, throughout world, as of 28 April 2020. The date of the first reported COVID-19 patient in 213 countries and regions around the world. The time sequence of reporting for each country is labeled according to the earliest (red) and latest (green) date of onset. Blue indicates no reporting available. Data source: World Health Organization (WHO); (B) The distribution of laboratory-confirmed cases throughout world, as of 28 April 2020. Spatial distribution of the 2,954,222 cases of COVID-19 diagnosed around the world. The cumulative number of confirmed diagnoses in each country is labeled in shades of red. Blue indicates no confirmed cases. Data source: People's Daily, Chinese Center for Disease Control and Prevention; World Health Organization (WHO); (C) The distribution of laboratory-confirmed cases throughout China, as of 29 April 2020. Distribution of the 84,369 cases of COVID-19 were diagnosed in China (including Hong Kong, Macao, and Taiwan) by city. The cumulative number of confirmed diagnoses in each city is labeled in shades of red. Data source: Chinese Center for Disease Control and Prevention.

Figure 2

The clinical symptoms, treatment and prevention of COVID-19 pneumonia. ARDS, acute respiratory distress syndrome; LDH, lactate dehydrogenase; ESR, erythrocyte sedimentation rate; mNGS, metagenomic next-generation sequencing; RT-PCR, reverse transcription- polymerase chain reaction; RT-LAMP, reverse transcription loop-mediated isothermal amplification; ELISA, enzyme-linked immunosorbent assay; GICA, gold immunochromatography assay; siRNA, small interfering RNA; ASO, antisense oligonucleotides; IFN- α, Interferon-α; QPD, qingfei paidu decoction.

Figure 3

Novel coronavirus life cycle and potential drug targets. Life cycle: (1) First, the virus binds to receptors on the surface of the host cell through the S-protein and is endocytosed or directly fused with the host cell membrane into the cell; (2) Next, the lysosome degrades the lipid membrane and protein envelope on the exterior of the virus (endocytosis only); (3) Viral RNA is released into the cell, where ORF1a and ORF1ab are translated into pp1a and pp1ab, which in turn are cleaved by proteases encoded by ORF1a to produce multiple NSPs, forming the replication/transcription complex; (4) At the same time as the previous step, viral RNA continues to use the cell for replication; (5) The replicated viral RNA undergoes discontinuous transcription under the action of the replication/transcription complex to produce subgenomic RNA, which is translated into structural proteins in the cell's endoplasmic reticulum; (6) The resulting structural proteins assemble in the ER-Golgi intermediate compartment (ERGIC) to form the nucleocapsid and viral envelope; (7) Finally, smooth-walled vesicles containing the nascent virus particles fuse with the cell membrane, releasing the virus particles from the infected cell. Drug targets: (1) Viral S-protein; (2) 3C-like protease and papain-like protease; (3) RNA-dependent RNA polymerase (RdRP). S, Spike protein; M, Membrane protein; E, Envelope protein; N, Nucleocapsid protein; NSPs, Non-structural proteins; DMV, Double-membrane vesicles; ER, Endoplasmic reticulum; ERGIC, ER–Golgi intermediate compartment.