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COVID-19 pandemic From Wikipedia, the free encyclopedia Jump to navigationJump to search For other coronavirus outbreaks, see Coronavirus outbreak (disambiguation) COVID‑19 pandemic COVID-19 Outbreak World Map per Capita.svg Confirmed cases per 100,000 population as of 18 October 2020 >3,000 1,000–3,000  300–1,000  100–300  30–100  0–30  None or no data show Total cases per country show Deaths per capita show Daily new cases A nurse caring for a patient with COVID‑19 in an intensive care unit Meeting of the Italian government task force to face the coronavirus outbreak, 23 February 2020 Taiwanese 33rd Chemical Corps spraying disinfectant on a street in Taipei, Taiwan Burial in Hamadan, Iran Workers unloading boxes of medical supplies at Villamor Air Base Clockwise from top: Nurse treating a COVID‑19 patient in an intensive care unit aboard a U.S. hospital ship Disinfection vehicles in Taiwan Donated medical supplies received in the Philippines Burial in Iran Italian government task force Disease	Coronavirus disease 2019 (COVID‑19) Virus strain	Severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2)[a] Source	Possibly via bats, pangolins, or both[2][3] Location	Worldwide First outbreak	Wuhan, China[4] Index case	Wuhan, Hubei, China 30°37′11″N 114°15′28″E Arrival date	Between 6 October 2019 and 11 December 2019[5] Date	31 December 2019[4] – present (10 months, 2 weeks and 4 days) Confirmed cases	39,803,562[6] Active cases	11,338,135[6] (28.1% of confirmed cases as of 24 September) Suspected cases‡	around 10% of the global population (C. 770 million), WHO estimate, October 2020 [7] Recovered	27,353,713[6] Deaths	1,111,714[6] Territories	189[6] ‡Suspected cases have not been confirmed as being due to this strain by laboratory tests, although some other strains may have been ruled out. The COVID-19 pandemic, also known as the coronavirus pandemic, is an ongoing pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).[1] The disease was first identified in December 2019 in Wuhan, China.[4] The outbreak was declared a Public Health Emergency of International Concern in January 2020, and a pandemic in March 2020. As of 18 October 2020, more than 39.8 million cases have been confirmed, with more than 1.11 million deaths attributed to COVID-19.[6]

COVID-19 spreads most often when people are physically close.[b] It spreads very easily and sustainably through the air, primarily via small droplets or aerosols, as an infected person breathes, coughs, sneezes, talks, or sings.[9][10] It may also be transmitted via contaminated surfaces, although this has not been conclusively demonstrated.[10][11][12] Airborne transmission from aerosol formation is suspected to be the main mode of transmission.[13] It can spread from an infected person for up to two days prior to symptom onset and from people who are asymptomatic.[10] People remain infectious for seven to twelve days in moderate cases and up to two weeks in severe cases.[10][14] Common symptoms include fever, cough, fatigue, breathing difficulties, and loss of smell. Complications may include pneumonia and acute respiratory distress syndrome. The incubation period is typically around five days but may range from one to 14 days.[14] There are several vaccine candidates in development, although none have proven their safety and efficacy. There is no known specific antiviral medication, so primary treatment is currently symptomatic.[15]

Recommended preventive measures include hand washing, covering mouth or wearing face mask when sneezing or coughing, social distancing, disinfecting surfaces, ventilation and air-filtering, and monitoring and self-isolation if exposed or symptomatic. Travel restrictions, lockdowns, workplace hazard controls, and facility closures have been implemented. Many places have also worked to increase testing capacity and trace contacts of the infected. These have caused social and economic disruption, including the largest global recession since the Great Depression.[16] Extreme poverty and global famines are affecting hundreds of millions, inflamed by supply shortages. Many events, the environment and education systems have also been affected. Misinformation about the virus has circulated globally. There have been many incidents of xenophobia and racism against Chinese people and against those perceived as being Chinese or as being from areas with high infection rates.[17]

Contents 1	Epidemiology 1.1	Background 1.2	Cases 1.3	Deaths 2	Transmission 3	Signs and symptoms 4	Cause 4.1	Virology 5	Diagnosis 5.1	Viral testing 5.2	Imaging 6	Prevention 6.1	Social distancing 6.2	Face masks and respiratory hygiene 6.3	Self-isolation 6.4	Ventilation and air filtration 6.5	Hand washing 6.6	Surface cleaning 6.7	Vaccine 7	Mitigation 7.1	Screening, containment and mitigation 7.2	Health care 8	Treatment 9	History 9.1	2019 9.2	2020 10	National responses 10.1	Asia 10.2	Europe 10.3	North America 10.4	South America 10.5	Africa 10.6	Oceania 11	International responses 11.1	Travel restrictions 11.2	Evacuation of foreign citizens 11.3	United Nations response measures 11.4	Protests against governmental measures 12	Impact 12.1	Economics 12.2	Culture 12.3	Politics 12.4	Agriculture and food systems 12.5	Famine 12.6	Education 12.7	Other health issues 12.8	Environment and climate 12.9	Xenophobia and racism 13	Information dissemination 13.1	Misinformation 14	See also 15	Notes 16	References 17	External links 17.1	Health agencies 17.2	Directories 17.3	Data and graphs 17.4	Medical journals Epidemiology For country-level data, see: COVID-19 pandemic by country and territory 732-bar-chart Cases 39,803,562 Deaths 1,111,714 As of 18 October 2020[6] Africa · Asia · Europe · North America Oceania · South America Background On 31 December 2019, the World Health Organisation (WHO) received reports of a cluster of viral pneumonia cases of an unknown cause in Wuhan, Hubei, China,[18] and an investigation was launched at the start of January 2020.[19] On 30 January, with 7,818 confirmed cases across 19 countries, the WHO declared the outbreak a Public Health Emergency of International Concern (PHEIC).[20][21]

Several early infected people had visited Huanan Seafood Wholesale Market;[22] the virus is therefore thought to be of zoonotic origin.[23] The virus that caused the outbreak is known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a newly discovered virus closely related to bat coronaviruses,[24] pangolin coronaviruses,[25][26] and SARS-CoV.[27] The scientific consensus is that COVID-19 has a natural origin.[28][29] The probable bat-to-human infection may have been among people processing bat carcasses and guano in the production of traditional Chinese medicines.[30]

The earliest known person with symptoms was later discovered to have fallen ill on 1 December 2019, and that person did not have visible connections with the later wet market cluster.[31][32] Of the early cluster of cases reported that month, two-thirds were found to have a link with the market.[33][34][35] On 13 March 2020, an unverified report from the South China Morning Post (SCMP) suggested a case traced back to 17 November 2019 (a 55-year-old person from Hubei) may have been the first person infected.[36][37] Phylogenic estimates in genetic studies conducted in early 2020 indicate that the SARS-CoV-2 virus likely jumped into the human population sometime between 6 October 2019 and 11 December 2019.[5]

The WHO recognised the spread of COVID-19 as a pandemic on 11 March 2020[38][39] as Italy, Iran, South Korea, and Japan reported increasing numbers of cases. Later that month, the number of cases outside of China quickly surpassed the number of cases inside China.[40]

In October 2020, the WHO stated, at a special meeting of WHO leaders, that one in ten people around the world may have been infected with COVID-19. At the time, that translated to 780 million people being infected, while only 35 million infections had been confirmed.[41]

An aerial view of the market, looking like a construction site. The Huanan Seafood Wholesale Market in March 2020, after it was closed down. Cases Main articles: COVID-19 pandemic by country and territory and COVID-19 pandemic cases Official case counts refer to the number of people who have been tested for COVID-19 and whose test has been confirmed positive according to official protocols.[42][43] Many countries, early on, had official policies to not test those with only mild symptoms.[44][45] An analysis of the early phase of the outbreak up to 23 January estimated 86 percent of COVID-19 infections had not been detected, and that these undocumented infections were the source for 79 percent of documented cases.[46] Several other studies, using a variety of methods, have estimated that numbers of infections in many countries are likely to be considerably greater than the reported cases.[47][48]

On 9 April 2020, preliminary results found that 15 percent of people tested in Gangelt, the centre of a major infection cluster in Germany, tested positive for antibodies.[49] Screening for COVID-19 in pregnant women in New York City, and blood donors in the Netherlands, has also found rates of positive antibody tests that may indicate more infections than reported.[50][51] Seroprevalence based estimates are conservative as some studies shown that persons with mild symptoms do not have detectable antibodies.[52] Some results (such as the Gangelt study) have received substantial press coverage without first passing through peer review.[53]

Analysis by age in China indicates that a relatively low proportion of cases occur in individuals under 20.[54] It is not clear whether this is because young people are less likely to be infected, or less likely to develop serious symptoms and seek medical attention and be tested.[55] A retrospective cohort study in China found that children and adults were just as likely to be infected.[56]

Initial estimates of the basic reproduction number (R0) for COVID-19 in January were between 1.4 and 2.5,[57] but a subsequent analysis concluded that it may be about 5.7 (with a 95 percent confidence interval of 3.8 to 8.9).[58] R0 can vary across populations and is not to be confused with the effective reproduction number (commonly just called R), which takes into account effects such as social distancing and herd immunity. By mid-May 2020, the effective R was close to or below 1.0 in many countries, meaning the spread of the disease in these areas at that time was stable or decreasing.[59]

Epidemic curve of daily new cases of COVID-19 (7 day rolling average) by continent

Semi-log plot of weekly new cases of COVID-19 in the world and top five current countries (mean with deaths) COVID-19 total cases per 100 000 population from selected countries[60]

COVID-19 active cases per 100 000 population from selected countries[60]