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COVID-19 pandemic

Ongoing pandemic of COVID-19

Top 10 COVID-19 pandemic related articles

COVID‑19 pandemic
Confirmed cases per 100,000 population as of 9 July 2020
Cases per country
Total confirmed cases per country as of 9 July 2020
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Deaths per capita
Confirmed deaths per million population as of 5 July 2020
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DiseaseCoronavirus disease 2019 (COVID‑19)
Virus strainSevere acute respiratory syndrome
coronavirus 2
SourceProbably bats, possibly via pangolins[2][3]
First outbreakChina[4]
Index caseWuhan, Hubei, China
30°37′11″N 114°15′28″E / 30.61972°N 114.25778°E / 30.61972; 114.25778
Date1 December 2019 (2019-12-01)[4]–present
(7 months, 1 week and 1 day)
Confirmed cases12,068,034[5][b]
Active cases4,906,351[5]

The COVID‑19 pandemic, also known as the coronavirus pandemic, is an ongoing global pandemic of coronavirus disease 2019 (COVID‑19), caused by severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2).[1] The outbreak was first identified in Wuhan, China, in December 2019.[4][6] The World Health Organization declared the outbreak a Public Health Emergency of International Concern on 30 January 2020 and a pandemic on 11 March.[7][8] As of 9 July 2020, more than 12 million cases of COVID‑19 have been reported in more than 188 countries and territories, resulting in more than 550,000 deaths; more than 6.61 million people have recovered.[5]

The virus is primarily spread between people during close contact,[c] most often via small droplets produced by coughing,[d] sneezing, and talking.[9][10][12] The droplets usually fall to the ground or onto surfaces rather than travelling through air over long distances,[9] although in some cases they may remain airborne for tens of minutes.[13] Less commonly, people may become infected by touching a contaminated surface and then touching their face.[9][10] It is most contagious during the first three days after the onset of symptoms, although spread is possible before symptoms appear, and from people who do not show symptoms.[9][10]

Common symptoms include fever, cough, fatigue, shortness of breath, and loss of sense of smell.[9][14][15] Complications may include pneumonia and acute respiratory distress syndrome.[16] The time from exposure to onset of symptoms is typically around five days but may range from two to fourteen days.[17][18] There is no known vaccine or specific antiviral treatment.[9] Primary treatment is symptomatic and supportive therapy.[19]

Recommended preventive measures include hand washing, covering one's mouth when coughing, maintaining distance from other people, wearing a face mask in public settings, and monitoring and self-isolation for people who suspect they are infected.[9][20] Authorities worldwide have responded by implementing travel restrictions, lockdowns, workplace hazard controls, and facility closures. Many places have also worked to increase testing capacity and trace contacts of infected persons.

The pandemic has caused global social and economic disruption,[21] including the largest global recession since the Great Depression.[22] It has led to the postponement or cancellation of sporting, religious, political, and cultural events,[23] widespread supply shortages exacerbated by panic buying,[24][25][26] and decreased emissions of pollutants and greenhouse gases.[27][28] Schools, universities, and colleges have been closed either on a nationwide or local basis in 172 countries, affecting approximately 98.5 percent of the world's student population.[29] Misinformation about the virus has circulated through social media and mass media.[30] There have been incidents of xenophobia and discrimination against Chinese people and against those perceived as being Chinese or as being from areas with high infection rates.[31]

Video summary (script) on the coronavirus disease (4:12 min)

COVID-19 pandemic Intro articles: 47



Location[e] Cases[b] Deaths[f] Recov.[g] Ref.
World[h] 12,068,034 550,159 6,611,524 [5]
United States[i] 3,109,500 134,291 936,249 [39]
Brazil[j] 1,716,196 68,055 1,117,922 [43][44]
India 767,296 21,129 476,377 [45]
Russia[k] 707,301 10,843 481,316 [46]
Peru 312,911 11,133 204,748 [47][48]
Chile[l] 306,216 6,682 274,992 [52]
United Kingdom[m] 287,621 44,602 No data [54][55]
Mexico 275,003 32,796 167,795 [56][57]
Spain[n] 252,513 28,396 150,376 [58]
Iran 248,379 12,084 209,463 [59]
Italy 242,149 34,914 193,640 [60][61]
Pakistan 240,848 4,983 145,311 [62]
South Africa 224,665 3,600 106,842 [63]
Saudi Arabia 220,144 2,059 158,050 [64]
Turkey 208,938 5,282 187,511 [65]
Germany[o] 198,765 9,115 183,094 [67][66]
Bangladesh 172,134 2,197 80,838 [68]
France[p] 170,094 29,979 77,985 [69]
Colombia 128,638 4,527 53,634 [70]
Canada 106,433 8,737 70,247 [71]
Qatar 102,110 142 97,272 [72]
Argentina[q] 87,017 1,694 36,489 [74][75]
China[r] 83,581 4,634 78,590 [76]
Egypt[s] 78,304 3,564 22,241 [77]
Sweden 74,333 5,550 No data [78]
Indonesia 70,736 3,417 32,651 [79]
Iraq 67,442 2,779 37,879 [80]
Belarus 64,224 443 52,854 [81]
Ecuador 63,245 4,873 5,900 [82][83]
Belgium[t] 62,123 9,776 17,138 [85]
United Arab Emirates 53,045 327 42,282 [86]
Kazakhstan 53,021 264 35,137 [87]
Kuwait 52,007 379 42,108 [88]
Netherlands[u] 50,746 6,135 No data [90]
Ukraine[v] 50,414 1,306 23,119 [91]
Philippines 50,359 1,314 12,588 [92][93]
Oman 50,207 233 32,005 [94]
Singapore 45,298 26 41,002 [95][96]
Portugal 44,859 1,631 29,714 [97]
Bolivia 42,984 1,577 12,883 [98]
Panama 41,251 819 19,469 [99][100]
Dominican Republic 39,588 829 20,056 [101]
Poland 36,689 1,542 24,878 [102][103]
Afghanistan 33,594 936 20,305 [104]
Israel[w] 33,557 344 18,338 [105]
Switzerland 32,498 1,686 29,400 [106][107]
Bahrain 30,931 98 26,073 [108]
Nigeria 30,249 684 12,373 [109]
Romania 30,175 1,817 20,799 [110]
Armenia 29,820 521 17,427 [111]
Honduras 25,978 694 2,721 [112][113]
Ireland 25,565 1,743 23,349 [114]
Guatemala 25,411 1,053 3,718 [115]
Ghana 22,822 129 17,564 [116]
Azerbaijan[x] 21,916 274 13,100 [117]
Japan[y] 20,174 980 17,331 [118]
Austria 18,513 706 16,721 [119]
Moldova[z] 18,471 614 11,549 [120]
Algeria 17,808 988 12,637 [121][122]
Serbia[aa] 17,076 341 13,064 [123]
Nepal 16,423 35 7,752 [124][125]
Cameroon 14,916 359 11,525 [126][127]
Morocco[ab] 14,771 242 11,316 [129]
South Korea 13,293 287 12,019 [130]
Denmark[ac] 12,900 609 12,001 [131]
Czech Republic 12,814 351 8,010 [132]
Ivory Coast 11,504 78 5,571 [133]
Uzbekistan 11,447 49 7,082 [134]
Sudan 10,084 636 5,074 [135]
Norway[ad] 8,954 251 8,138 [138]
Australia[ae] 8,886 106 7,487 [139]
Malaysia 8,677 121 8,486 [140]
El Salvador 8,566 235 5,133 [141]
Kenya 8,975 173 2,657 [142]
Kyrgyzstan 8,486 112 2,983 [143]
Venezuela 8,010 75 2,544 [144]
Senegal 7,657 141 5,097 [145]
DR Congo[af] 7,432 182 3,226 [146]
North Macedonia 7,406 359 3,554 [147][148]
Finland[ag] 7,265 329 6,800 [151]
Ethiopia 6,774 120 2,430 [152]
Haiti 6,486 123 2,181 [153]
Tajikistan 6,364 54 5,011 [154]
Bulgaria 6,102 254 3,037 [155]
Gabon 5,871 46 2,682 [156]
Bosnia and Herzegovina 5,869 209 2,769 [157]
Costa Rica 5,836 24 1,929 [158]
Guinea 5,697 34 4,577 [159][160]
Mauritania 5,087 139 1,994 [161]
Palestine 5,029 20 494 [162]
Djibouti 4,889 55 4,644 [163]
Luxembourg 4,650 110 4,056 [164]
Hungary 4,220 591 2,887 [165]
Central African Republic 4,109 52 976 [166]
Kosovo 3,886 82 2,003 [167]
Greece 3,589 193 1,374 [168]
Madagascar 3,573 33 1,761 [169]
Croatia 3,325 114 2,277 [170]
Thailand 3,202 58 3,085 [171]
Albania 3,106 83 1,791 [172]
Equatorial Guinea 3,071 51 842 [173]
Somalia[ah] 3,028 92 1,147 [174]
Paraguay 2,554 20 1,212 [175]
Maldives 2,517 13 2,158 [176]
Cuba[ai] 2,399 86 2,242 [177]
Mali 2,358 120 1,597 [178]
Nicaragua 2,182 83 1,750 [102][179]
Sri Lanka 2,094 11 1,967 [180]
South Sudan 2,021 38 333 [181][182]
Estonia 2,003 69 1,882 [183]
Lebanon 1,946 36 1,368 [184]
Zambia 1,895 42 1,348 [185][186]
Iceland 1,880 10 1,850 [187]
Malawi 1,942 25 369 [188]
Puerto Rico 1,846 155 840 [189][190]
Lithuania 1,854 79 1,552 [191]
Congo[aj] 1,821 44 501 [192][193]
Slovakia 1,798 28 1,473 [194]
Guinea-Bissau 1,790 25 760 [195]
Slovenia 1,773 111 1,384 [196][197]
Sierra Leone 1,584 63 1,122 [198][199]
Cape Verde 1,542 18 730 [200]
Yemen 1,318 351 595 [201]
Hong Kong 1,324 7 1,167 [202]
Donetsk PR[ak] 1,290 78 570 [203]
Libya 1,268 36 306 [204][205]
Tunisia 1,221 50 1,050 [206]
Benin 1,199 21 333 [207]
Rwanda 1,194 3 610 [208][209]
New Zealand 1,187 22 1,140 [210]
Jordan 1,169 10 977 [211]
Latvia 1,141 30 1,008 [102][212]
Eswatini 1,138 13 588 [213]
USS Theodore Roosevelt[al] 1,102 1 751 [214][215]
Niger 1,097 68 976 [216]
Charles de Gaulle[am] 1,081 0 0 [217]
Mozambique 1,071 6 337 [221]
Cyprus[an] 1,008 19 839 [222]
Burkina Faso 1,003 53 858 [223][224]
Uganda 977 0 904 [225][226]
Uruguay[ao] 974 29 871 [227]
Georgia[ap] 963 15 841 [228]
Montenegro 960 17 320 [229]
Liberia 926 41 395 [230]
Zimbabwe 885 9 206 [231][232]
Chad 873 74 788 [233]
Andorra 855 52 802 [234]
Jamaica 745 10 599 [235][236]
São Tomé and Príncipe 724 13 283 [237]
Diamond Princess[y] 712 14 653 [238][239]
San Marino 698 42 656 [240]
Togo 695 15 475 [241]
Malta 673 9 654 [242]
Suriname 671 17 435 [243]
Namibia 615 0 25 [244][245]
Somaliland[aq] 560 27 176 [246]
Luhansk PR[ak] 542 13 464 [247]
Taiwan[ar] 449 7 438 [249]
Angola 396 22 117 [250]
Syria[as] 372 14 126 [251]
Vietnam 369 0 347 [252]
Mauritius 342 10 330 [253]
Isle of Man[at] 336 24 312 [254]
Jersey 325 15 303 [255]
Myanmar 317 6 250 [256]
Botswana 314 1 31 [257]
Comoros 313 7 272 [258]
Guam[al] 307 5 202 [39][259]
Guyana 284 16 125 [260]
Guernsey 252 13 238 [261]
Mongolia 227 0 195 [262]
Eritrea 215 0 56 [263]
Cayman Islands 201 1 194 [264]
Burundi 191 1 118 [265]
Faroe Islands 188 0 188 [266]
Gibraltar 179 0 176 [267]
Bermuda 149 9 137 [268]
Costa Atlantica 148 0 148 [269][270]
Brunei 141 3 138 [271][272]
Artsakh[au] 141 0 112 [273]
Cambodia 141 0 131 [274]
Trinidad and Tobago 133 8 117 [275]
Greg Mortimer[ao] 128 1 No data [276][277]
U.S. Virgin Islands 122 6 80 [278]
Northern Cyprus[av] 113 4 104 [279]
Monaco 108 4 95 [280]
Aruba 105 3 98 [281]
Bahamas 104 11 89 [282]
Barbados 98 7 90 [283]
Lesotho 91 0 11 [284]
Seychelles 91 0 11 [285]
South Ossetia[aw] 85 0 85 [273]
Liechtenstein 84 1 81 [286][287]
Bhutan 80 0 55 [288]
Sint Maarten 78 15 63 [289]
Antigua and Barbuda 70 3 23 [290]
The Gambia 63 3 32 [291]
French Polynesia 62 0 60 [292]
Turks and Caicos Islands 55 2 11 [293]
Macau 46 0 45 [294]
Abkhazia[ax] 38 1 35 [273]
Belize 30 2 19 [295]
Northern Mariana Islands 30 2 19 [296]
Saint Vincent[ay] 29 0 29 [297][298]
Curaçao 25 1 23 [299]
East Timor 24 0 24 [300]
Grenada 23 0 23 [301][302]
Saint Lucia 22 0 19 [303][304]
Fiji 21 0 18 [305]
New Caledonia 21 0 21 [306]
Laos 19 0 19 [307]
Dominica 18 0 18 [308]
Saint Kitts and Nevis 16 0 15 [309]
Falkland Islands 13 0 13 [310]
Greenland 13 0 13 [311]
MS Zaandam[az] 13 4 No data [314][315]
Coral Princess[ba] 12 3 No data [317]
Vatican City 12 0 12 [318]
Montserrat 11 1 10 [319]
Papua New Guinea 11 0 8 [320]
British Virgin Islands 8 1 7 [321]
HNLMS Dolfijn[bb] 8 0 8 [322][325]
Anguilla 3 0 3 [326]
Saba 3 0 3 [327]
Bonaire 2 0 2 [328]
Sint Eustatius 2 0 2 [329]
Saint Pierre and Miquelon 1 0 1 [330]
Tanzania[bc] No data No data No data [334][335]
As of 9 July 2020 (UTC) · History of cases · History of deaths
For notes, see the Notes section.

On 31 December 2019, the World Health Organization (WHO) got reports from health authorities in China of a cluster of viral pneumonia cases of unknown cause in Wuhan, Hubei,[336][337] and an investigation was launched at the start of January 2020.[338] On 30 January, the WHO declared the outbreak a Public Health Emergency of International Concern (PHEIC)—7,818 cases confirmed globally, affecting 19 countries in five WHO regions.[339][7]

Several early infected had visited Huanan Seafood Wholesale Market;[340] the virus is therefore thought to be of zoonotic origin.[341] The virus that caused the outbreak is known as SARS‑CoV‑2, a newly discovered virus closely related to bat coronaviruses,[342] pangolin coronaviruses,[343][344] and SARS-CoV.[345] The scientific consensus is that COVID-19 has a natural origin.[346][347] The probable bat-to-human infection may have been among people processing bat carcasses and guano in the production of traditional Chinese medicines.[348]

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.[349][350] Of the early cluster of cases reported that month, two-thirds were found to have a link with the market.[351][352][353] On 13 March 2020, an unverified report from the South China Morning Post suggested a case traced back to 17 November 2019 (a 55-year-old from Hubei) may have been the first person infected.[354][355]

The WHO recognized the spread of COVID-19 as a pandemic on 11 March 2020[8] as Italy, Iran, South Korea, and Japan reported surging cases. The total numbers outside China quickly passed China's.[356]


Cases refer to the number of people who have been tested for COVID-19, and whose test has been confirmed positive according to official protocols.[357] As of 24 May, countries that publicised their testing data have typically performed many tests equal to 2.6 percent of their population, while no country has tested samples equal to more than 17.3 percent of its population.[358] Many countries, early on, had official policies to not test those with only mild symptoms.[359][360] 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.[361] 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.[362][363]

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.[364] 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.[365][366] However, such antibody surveys can be unreliable due to a selection bias in who volunteers to take the tests, and due to false positives. Some results (such as the Gangelt study) have received substantial press coverage without first passing through peer review.[367]

Analysis by age in China indicates that a relatively low proportion of cases occur in individuals under 20.[368] 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.[369] A retrospective cohort study in China found that children were as likely to be infected as adults.[370] Countries that test more, relative to the number of deaths, have a younger age distribution of cases, relative to the wider population.[371]

Initial estimates of the basic reproduction number (R0) for COVID-19 in January were between 1.4 and 2.5,[372] but a subsequent analysis concluded that it may be about 5.7 (with a 95 percent confidence interval of 3.8 to 8.9).[373] 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.[374]


Deceased in a 16 m (53 ft) "mobile morgue" outside a hospital in Hackensack, New Jersey

Most people who contract COVID-19 recover. For those who do not, the time between the onset of symptoms and death usually ranges from 6 to 41 days, typically about 14 days.[379] As of 9 July 2020, approximately 550,000[5] deaths had been attributed to COVID-19. In China, as of 14 June, about 80 percent of deaths were recorded in those aged over 60, and 75 percent had pre-existing health conditions including cardiovascular diseases and diabetes.[380]

The first confirmed death was in Wuhan on 9 January 2020.[381] The first death outside of China occurred on 1 February in the Philippines,[382] and the first death outside Asia was in France on 14 February.[383]

Official deaths from COVID-19 generally refer to people who died after testing positive according to protocols. This may ignore deaths of people who die without testing, e.g. at home or in nursing homes.[384] Conversely, deaths of people who had underlying conditions may lead to overcounting.[385] Comparison of statistics for deaths for all causes versus the seasonal average indicates excess mortality in many countries.[386][387] In the worst affected areas, mortality has been several times higher than average. In New York City, deaths have been four times higher than average, in Paris twice as high, and in many European countries, deaths have been on average 20 to 30 percent higher than normal.[386] This excess mortality may include deaths due to strained healthcare systems and bans on elective surgery.[388]

Multiple measures are used to quantify mortality.[389] These numbers vary by region and over time, influenced by testing volume, healthcare system quality, treatment options, government response,[390][391][392] time since the initial outbreak, and population characteristics, such as age, sex, and overall health.[393] Some countries (like Belgium) include deaths from suspected cases of COVID-19, regardless of whether the person was tested, resulting in higher numbers compared to countries that include only test-confirmed cases.[394]

The death-to-case ratio reflects the number of deaths attributed to COVID-19 divided by the number of diagnosed cases within a given time interval. Based on Johns Hopkins University statistics, the global death-to-case ratio is 4.6 percent (550,159 deaths for 12,068,034 cases) as of 9 July 2020.[5] The number varies by region.[395]

Other measures include the case fatality rate (CFR), which reflects the percentage of diagnosed people who die from a disease, and the infection fatality rate (IFR), which reflects the percentage of infected (diagnosed and undiagnosed) who die from a disease. These statistics are not timebound and follow a specific population from infection through case resolution. Our World in Data states that as of 25 March 2020 the IFR cannot be accurately calculated as neither the total number of cases nor the total deaths, is known.[393] In February the Institute for Disease Modeling estimated the IFR as 0.94 percent (95-percent confidence interval 0.37–2.9), based on data from China.[396][397] The University of Oxford's Centre for Evidence-Based Medicine (CEBM) estimated a global CFR of 0.8 to 9.6 percent (last revised 30 April) and IFR of 0.10 percent to 0.41 percent (last revised 2 May), acknowledging that this will vary between populations due to differences in demographics.[398] The CDC estimates for planning purposes that the fatality rate among those who are symptomatic is 0.4 percent (0.2 to 1.0 percent) and that 35 percent of infected individuals are asymptomatic, for an overall infection fatality rate of 0.26 percent (as of 20 May).[399][400]


On 11 March 2020, the WHO said the pandemic could be controlled.[8] The peak and ultimate duration of the outbreak are uncertain and may differ by location. Maciej Boni of Penn State University said, "Left unchecked, infectious outbreaks typically plateau and then start to decline when the disease runs out of available hosts. But it's almost impossible to make any sensible projection right now about when that will be."[403] The Imperial College study led by Neil Ferguson stated that physical distancing and other measures will be required "until a vaccine becomes available (potentially 18 months or more)".[404] William Schaffner of Vanderbilt University said because the coronavirus is "so readily transmissible", it "might turn into a seasonal disease, making a comeback every year". The virulence of the comeback would depend on herd immunity and the extent of mutation.[405]

COVID-19 pandemic Epidemiology articles: 38

Signs and symptoms

Symptoms of COVID-19[406]

The usual incubation period (the time between infection and symptom onset) ranges from one to 14 days, and is most commonly five days.[9][407] Some infected people have no symptoms, known as asymptomatic or presymptomatic carriers; transmission from such a carrier is considered possible.[408] As at 6 April, estimates of the asymptomatic ratio range widely from 5 to 80 percent.[409]

Symptoms of COVID-19 can be relatively non-specific; the two most common symptoms are fever (88 percent) and dry cough (68 percent). Less common symptoms include fatigue, respiratory sputum production (phlegm), loss of the sense of smell, loss of taste, shortness of breath, muscle and joint pain, sore throat, headache, chills, vomiting, coughing out blood, diarrhea, and rash.[410][16][15]

Among those who develop symptoms, approximately one in five may become more seriously ill and have difficulty breathing.[9] Emergency symptoms include difficulty breathing, persistent chest pain or pressure, sudden confusion, difficulty waking, and bluish face or lips; immediate medical attention is advised if these symptoms are present.[15] Further development of the disease can lead to complications including pneumonia, acute respiratory distress syndrome, sepsis, septic shock, and kidney failure.[16]

COVID-19 pandemic Signs and symptoms articles: 7



Respiratory droplets produced when a man sneezes, visualised using Tyndall scattering

COVID-19 spreads primarily when people are in close contact and one person inhales small droplets produced by an infected person (symptomatic or not) coughing, sneezing, talking, or singing.[12][411] The WHO recommends 1 metre (3 ft) of social distance;[9] the US Centers for Disease Control and Prevention (CDC) recommends 2 metres (6 ft).[10] People can transmit the virus without showing symptoms, but it is unclear how often this happens.[9][10][12] A June 2020 review found the likelihood of those infected that are asymptomatic to be 40-45%.[412]

People are most infectious when they show symptoms (even mild or non-specific symptoms), but may be infectious for up to two days before symptoms appear (pre-symptomatic transmission).[12] They remain infectious an estimated seven to twelve days in moderate cases and an average of two weeks in severe cases.[12]

When the contaminated droplets fall to floors or surfaces they can, though less commonly, remain infectious if people touch contaminated surfaces and then their eyes, nose or mouth with unwashed hands.[9] On surfaces the amount of active virus decreases over time until it can no longer cause infection,[12] and surfaces are thought not to be the main way the virus spreads.[10] It is unknown what amount of virus on surfaces is required to cause infection via this method, but it can be detected for up to four hours on copper, up to one day on cardboard, and up to three days on plastic (polypropylene) and stainless steel (AISI 304).[12][413][414] Surfaces are easily decontaminated with household disinfectants which kill the virus outside the human body or on the hands.[9] Disinfectants or bleach are not a treatment for COVID‑19, and cause health problems when not used properly, such as when used inside the human body.[415]

Sputum and saliva carry large amounts of virus.[9][10][12][416] Although COVID‑19 is not a sexually transmitted infection, kissing, intimate contact, and faecal-oral routes are suspected to transmit the virus.[417][418] Some medical procedures are aerosol-generating,[419] and result in the virus being transmitted more easily than normal.[9][12]

COVID‑19 is a new disease, and many of the details of its spread are still under investigation.[9][10][12] It spreads easily between people—easier than influenza but not as easily as measles,[10] and it is alleged the virus is likely airborne, while experimental results show the virus can survive in aerosol up to three hours.[420] Estimates of the number of people infected by one person with COVID-19, the R0, have varied. The WHO's initial estimates of R0 were 1.4-2.5 (average 1.95), however am early April 2020 review found the basic R0 (without control measures) to be higher at 3.28 and the median R0 to be 2.79.[421]

The virus may occur in breast milk, but it's unknown whether it's infectious and transmittable to the baby.[422][423]


Illustration of SARSr‑CoV virion

Severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) is a novel virus, first isolated from three people with pneumonia connected to the cluster of acute respiratory illness cases in Wuhan.[345] All features of the novel SARS‑CoV‑2 virus occur in related coronaviruses in nature.[424]

SARS‑CoV‑2 is closely related to SARS‑CoV, and is thought to have a zoonotic origin.[342] SARS‑CoV‑2 genetically clusters with the genus Betacoronavirus, and is 96 percent identical at the whole genome level to other bat coronavirus samples[425] and 92 percent identical to pangolin coronavirus.[426]

COVID-19 pandemic Cause articles: 13


Demonstration of a swab for COVID-19 testing

COVID-19 can be provisionally diagnosed on the basis of symptoms and confirmed using reverse transcription polymerase chain reaction (RT-PCR) testing of infected secretions or CT imaging of the chest.[427][428]

Viral testing

The standard test for current infection with SARS-CoV-2 uses RNA testing of respiratory secretions collected using a nasopharyngeal swab, though it is possible to test other samples. This test uses real-time rRT-PCR which detects the presence of viral RNA fragments.[429]

A number of laboratories and companies have developed serological tests, which detect antibodies produced by the body in response to infection.[430] Several have been evaluated by Public Health England and approved for use in the UK.[431]

On 22 June 2020, UK health secretary Matt Hancock announced the country would conduct a new "spit test" for COVID-19 on 14,000 key workers and their families in Southampton, having them spit in a pot, which was collected by Southampton University, with results expected within 48 hours. Hancock said the test was easier than using swabs, and could enable people to conduct it at home.[432]


A CT scan of a person with COVID‑19 shows lesions (bright regions) in the lungs.

Characteristic imaging features on chest radiographs and computed tomography (CT) of people who are symptomatic include asymmetric peripheral ground-glass opacities without pleural effusions.[433] The Italian Radiological Society is compiling an international online database of imaging findings for confirmed cases.[434] Due to overlap with other infections such as adenovirus, imaging without confirmation by rRT-PCR is of limited specificity in identifying COVID-19.[433] A large study in China compared chest CT results to PCR and demonstrated that though imaging is less specific for the infection, it is faster and more sensitive.[428]

COVID-19 pandemic Diagnosis articles: 18


Infographic by the U.S. Centers for Disease Control and Prevention (CDC), describing how to stop the spread of germs

Strategies for preventing transmission of the disease include maintaining overall good personal hygiene, washing hands, avoiding touching the eyes, nose, or mouth with unwashed hands, and coughing or sneezing into a tissue, and putting the tissue directly into a waste container. Those who may already have the infection have been advised to wear a surgical mask in public.[435][436] Physical distancing measures are also recommended to prevent transmission.[437][438] Health care providers taking care of someone who may be infected are recommended to use standard precautions, contact precautions, and eye protection.[439]

Many governments have restricted or advised against all non-essential travel to and from areas affected by the outbreak.[440] The virus has already spread within communities in large parts of the world, with many not knowing where or how they were infected.[441]

Misconceptions are circulating about how to prevent infection; for example, rinsing the nose and gargling with mouthwash are not effective.[442] There is no COVID-19 vaccine, though many organisations are working to develop one.[443]

Hand washing

Hand washing is recommended to prevent the spread of the disease. The CDC recommends that people wash hands often with soap and water for at least twenty seconds, especially after going to the toilet or when hands are visibly dirty; before eating; and after blowing one's nose, coughing, or sneezing. This is because outside the human body, the virus is killed by household soap, which bursts its protective bubble.[20] CDC further recommended using an alcohol-based hand sanitiser with at least 60 percent alcohol by volume when soap and water are not readily available.[435] The WHO advises people to avoid touching the eyes, nose, or mouth with unwashed hands.[436][444] It is not clear whether washing hands with ash, if soap is not available, is effective at reducing the spread of viral infections.[445]

Social distancing

Physical distancing in Toronto, with a limited number of customers allowed inside a store

Social distancing (also known as physical distancing) includes infection control actions intended to slow the spread of disease by minimising close contact between individuals. Methods include quarantines; travel restrictions; and the closing of schools, workplaces, stadiums, theatres, or shopping centres. Individuals may apply social distancing methods by staying at home, limiting travel, avoiding crowded areas, using no-contact greetings, and physically distancing themselves from others.[436][446][447] Many governments are now mandating or recommending social distancing in regions affected by the outbreak.[448][449] Non-cooperation with distancing measures in some areas has contributed to the further spread of the pandemic.[450]

The maximum gathering size recommended by U.S. government bodies and health organisations was swiftly reduced from 250 people (if there were no known COVID-19 spread in a region) to 50 people, and later to 10.[451] On 22 March 2020, Germany banned public gatherings of more than two people.[452] A Cochrane review found that early quarantine with other public health measures are effective in limiting the pandemic, but the best manner of adopting and relaxing policies are uncertain, as local conditions vary.[447]

Older adults and those with underlying medical conditions such as diabetes, heart disease, respiratory disease, hypertension, and compromised immune systems face increased risk of serious illness and complications and have been advised by the CDC to stay home as much as possible in areas of community outbreak.[453][454]

In late March 2020, the WHO and other health bodies began to replace the use of the term "social distancing" with "physical distancing", to clarify that the aim is to reduce physical contact while maintaining social connections, either virtually or at a distance. The use of the term "social distancing" had led to implications that people should engage in complete social isolation, rather than encouraging them to stay in contact through alternative means.[455][456] Some authorities have issued sexual health guidelines for the pandemic, which include recommendations to have sex only with someone you live with, and who does not have the virus or symptoms of the virus.[457][458]

Face masks and respiratory hygiene

The CDC and WHO advise that masks reduce the spread of coronavirus by asymptomatic and pre-symtomatic individuals.

The CDC and WHO recommend individuals wear non-medical face coverings in public settings where there is an increased risk of transmission and where social distancing measures are difficult to maintain.[459][460][461] This recommendation is meant to reduce the spread of the disease by asymptomatic and pre-symtomatic individuals and is complementary to established preventive measures such as social distancing.[460][462] Face coverings limit the volume and travel distance of expiratory droplets dispersed when talking, breathing, and coughing.[460][462] Many countries and local jurisdictions encourage or mandate the use of face masks or cloth face coverings by members of the public to limit the spread of the virus.[463][460][464][465]

Masks are also strongly recommended for those who may have been infected and those taking care of someone who may have the disease.[466] When not wearing a mask, the CDC recommends covering the mouth and nose with a tissue when coughing or sneezing and recommends using the inside of the elbow if no tissue is available.[435] Proper hand hygiene after any cough or sneeze is encouraged.[435] Healthcare professionals interacting directly with COVID-19 patients are advised to use respirators at least as protective as NIOSH-certified N95 or equivalent, in addition to other personal protective equipment.[467]


Without pandemic containment measures—such as social distancing, vaccination, and use of face masks—pathogens can spread exponentially.[468] This graphic shows how early adoption of containment measures tends to protect wider swaths of the population.

Self-isolation at home has been recommended for those diagnosed with COVID-19 and those who suspect they have been infected. Health agencies have issued detailed instructions for proper self-isolation.[469][470]

Many governments have mandated or recommended self-quarantine for entire populations.[471][472] The strongest self-quarantine instructions have been issued to those in high risk groups.[473] Those who may have been exposed to someone with COVID-19 and those who have recently travelled to a country or region with the widespread transmission have been advised to self-quarantine for 14 days from the time of last possible exposure.[9][17][474]

Surface cleaning

Surfaces may be decontaminated with a number of solutions (within one minute of exposure to the disinfectant for a stainless steel surface), including 62–71 percent ethanol, 50–100 percent isopropanol, 0.1 percent sodium hypochlorite, 0.5 percent hydrogen peroxide, and 0.2–7.5 percent povidone-iodine. Other solutions, such as benzalkonium chloride and chlorhexidine gluconate, are less effective.[475] The CDC recommends that if a COVID-19 case is suspected or confirmed at a facility such as an office or day care, all areas such as offices, bathrooms, common areas, shared electronic equipment like tablets, touch screens, keyboards, remote controls, and ATM machines used by the ill persons should be disinfected.[476]

COVID-19 pandemic Prevention articles: 22