COVID-19
Coronaviruses are a variety of viruses that infect many animals and can cause moderate or severe respiratory infections in humans. In 2002 and 2012, respectively, two powerful coronaviruses with the zoonotic origin, acute respiratory syndrome (SARS-CoV) and the Middle East Respiratory Syndrome coronavirus (MERS-CoV), originated in humans and caused fatal illness. Respiratory, which makes the developing coronaviruses into a coronavirus. New public health concerns in the 21st century1. In late 2019, a novel coronavirus called SARS-CoV-2 emerged in the city of Wuhan, China, and triggered an outbreak of rare viral pneumonia. As it is highly contagious, the novel coronavirus of the novel, also known as coronavirus 2019 (COVID-19), has spread rapidly around the world 2.3. SARS and MERS have outpaced the number of people infected with the virus and the list of epidemics. The ongoing outbreak of COVID-19 has posed a serious threat to public health worldwide4.5. In this Review, we summarize the current environmental understanding of SARS-CoV-2 and COVID-19. Based on the results of the recently published results, this Complete Review covers the basic biology of SARS-CoV-2, which includes genetic factors, potential zoonotic origin, and its receptor binding. In addition, we will discuss clinical features and epidemics, diagnoses, and measures to combat COVID-19.
Appearance and spread
At the end of December 2019, several health facilities in Wuhan, Hubei province in China, reported groups of patients with pneumonia of unknown cause6. Similarly, in patients with SARS and MERS, these patients showed symptoms of viral pneumonia, including fever, cough, and chest tightness, and in severe cases dyspnea and pneumonia in two countries6, 7. Among the first 27 hospitalized patients were listed, many cases were linked to the epidemiologically Huanan Seafood Wholesale Market a liquid market located in the city of Wuhan, which sells not only seafood but also live animals, including poultry, and wildlife4, 8. According to a previous study, the start of the first known case goes back to 8 December 2019 (REF .9). On December 31, the Wuhan Municipal Health Commission informed the public of an outbreak of pneumonia for an unknown reason and informed the World Health Organization (WHO) 9 (FIG. 1). Following metagenomic RNA sequence and viral differentiation in bronchoalveolar clearance fluid samples in patients with severe pneumonia, independent groups of Chinese scientists have identified the cause of the emerging disease as unprecedented betacoronavirus6,10,11. On 9 January 2020, the result of this etiological diagnosis was announced publicly (FIG. 1). The first genetic sequence of the novel coronavirus was published on the Virological Web site on January 10, and almost complete genetic sequences determined by the various research institutes were released on the GISAID website on 12 January 7. Later, many patients with no history of exposure to Huanan Seafood Wholesale Market have been identified as reporting more family infections, and nosocomial infections also occur in health facilities. All of these cases have provided clear evidence of human transmission of the new virus4, 12-14. As the outbreak of the disease coincides with the approaching New Year's Eve, traveling between cities before the festival facilitates the transmission of the virus to China. The novel coronavirus pneumonia spread to other cities in Hubei province and parts of China. Within a month it was widely distributed in all 34 provinces of China. The number of confirmed cases has skyrocketed, with thousands of new cases being discovered daily by the end of January 15. On January 30, the WHO announced the outbreak of the novel coronavirus a public health emergency that worries internationally. 2 ', and the WHO named the disease' COVID-19 '(REF.17).
The outbreak of COVID-19 in China reached an all-time high in February. According to China's National Health Commission, the number of cases continued to rise sharply in early February with an average of more than 3,000 recently confirmed cases per day. Controlling COVID-19, China adopted the strongest public health measures ever. The city of Wuhan was closed on January 23, and all travel and transportation connecting the city were closed. Over the next few weeks, all outdoor activities and gatherings were restricted, and public areas were closed in many cities and villages18. As a result of these measures, the daily number of new cases in China has begun to decline gradually19.
However, despite the decline in practice in China, the global distribution of COVID-19 has grown since the end of February. Large numbers of infections have been reported in a growing number of countries18. The high efficiency of SARS-CoV-2 transmission and the high international exposure has led to the rapid global spread of COVID-19. On 11 March 2020, the WHO officially recognized the global outbreak of COVID-19 as a pandemic20. Since March, when COVID-19 in China was successfully regulated, the number of cases in Europe, the USA, and other regions have skyrocketed. According to the COVID-19 dashboard of the Center for System Science and Engineering at Johns Hopkins University, as of 11 August 2020, 216 countries and regions from all six continents have reported more than 20 million cases of COVID-19, and more than -733,000. 21 patients had died. High mortality occurs especially when health care facilities are overcrowded. The USA is the country with the highest number of cases to date.
Although genetic evidence suggests that SARS-CoV-2 is a natural virus that may have originated in animals, there are still no conclusions as to when and where the virus originated.
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