Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and represents a potentially fatal disease of great global public health importance. As of March 26, 2020, the outbreak of COVID-19 has resulted in 462,801 confirmed cases and 20,839 deaths globally, which is more than those caused by SARS and Middle East respiratory syndrome (MERS) in 2003 and 2013, respectively. The epidemic has posed considerable challenges worldwide. Under a strict mechanism of massive prevention and control, China has seen a rapid decrease in new cases of coronavirus; however, the global situation remains serious. Additionally, the origin of COVID-19 has not been determined and no specific antiviral treatment or vaccine is currently available. Based on the published data, this review systematically discusses the etiology, epidemiology, clinical characteristics, and current intervention measures related to COVID-19 in the hope that it may provide a reference for future studies and aid in the prevention and control of the COVID-19 epidemic.
In December 2019, a cluster of cases of unexplained viral pneumonia was identified in Wuhan, a metropolitan city in Hubei province, China. Initially, most of the confirmed cases were linked with the Huanan seafood market in Wuhan, where numerous types of live wild animals are sold, including poultry, bats, groundhogs, and snakes. To identify the causative agent of this disease, a large number of tests were conducted, which ruled out several etiological agents that may cause similar symptoms, including the severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV), avian influenza virus, and other common respiratory pathogens. Finally, a new coronavirus, putatively named 2019-nCoV by the World Health Organization (WHO) on January 12, 2020, was identified as the causative pathogen of this outbreak. On January 20, after a visit to Wuhan, Professor Zhong Nanshan, a SARS intervention specialist, confirmed that 2019-nCoV was spreading between people , which led to increased vigilance by the Chinese government and people. At 10:00 on January 23, Wuhan, the birthplace of the disease, declared a general closure to prevent its further spread. However, Wuhan is a major transportation hub located in the central region of the People‟s Republic of China with approximately 11 million inhabitants , and the period from the end of December 2019 to February 2020 was the time of the “Spring Festival travel rush”. Although the Chinese government made great efforts to control the flow of people, the disease spread rapidly from Wuhan to other cities, as well as other countries, likely through asymptomatic carriers .