2019–20 Coronavirus Pandemic (Covid-19)
The 2019–20 coronavirus pandemic is an ongoing pandemic of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The outbreak was first identified in Wuhan, Hubei, China, in December 2019, and was recognised as a pandemic by the World Health Organization (WHO) on 11 March 2020. As of 23 March, more than 372,000 cases of COVID-19 have been reported in over 190 countries and territories, resulting in more than 16,300 deaths and over 101,000 recoveries.
The virus is typically spread from one person to another via respiratory droplets produced during coughing. It primarily spreads when people are in close contact but may also spread when one touches a contaminated surface and then their face. It is most contagious when people are symptomatic, although spread may be possible before symptoms appear. The time between exposure and symptom onset is typically around five days, but may range from two to fourteen days. Common symptoms include fever, cough, and shortness of breath. Complications may include pneumonia and acute respiratory distress syndrome. There is no vaccine or specific antiviral treatment. Primary treatment is symptomatic and supportive therapy. Recommended preventive measures include hand washing, covering the mouth when coughing, maintaining distance from other people, and monitoring and self-isolation for people who suspect they are infected.
Efforts to prevent the virus spreading include travel restrictions, quarantines, curfews, event postponements and cancellations, and facility closures. These include a quarantine of Hubei, nationwide quarantines in Italy and elsewhere in Europe, curfew measures elsewhere in China and South Korea, various border closures or incoming passenger restrictions, screening at airports and train stations, and travel advisories regarding regions with community transmission. Schools and universities have closed either on a nationwide or local basis in over 124 countries, affecting more than 1.2 billion students.
The pandemic has led to global socioeconomic disruption, the postponement or cancellation of sporting, religious, and cultural events, and widespread fears of supply shortages which have spurred panic buying. Misinformation and conspiracy theories about the virus have spread online, and there have been incidents of xenophobia and racism against Chinese and other East or Southeast Asian people.
Epidemiology
Health authorities in Wuhan, the capital of Hubei province, China, reported a cluster of pneumonia cases of unknown cause on 31 December 2019, and an investigation was launched in early January 2020. The cases mostly had links to the Huanan Seafood Wholesale Market and so the virus is thought to have a zoonotic origin. The virus that caused the outbreak is known as SARS-CoV-2, a newly discovered virus closely related to bat coronaviruses, pangolin coronaviruses and SARS-CoV.
The earliest person with symptoms was traced back to 1 December 2019, someone who did not have connections with the later cluster linked to the wet market. Of the early cluster of cases reported in December 2019, two-thirds were found to have a link with the market. On 14 March 2020, an unverified report from the South China Morning Post said that a 55-year-old from Hubei province could have been the first person who contracted the disease, on 17 November.
On 26 February 2020, the WHO reported that, as new cases reportedly dropped in China but suddenly increased in Italy, Iran, and South Korea, the number of new cases outside China had exceeded the number of new cases in China for the first time. There may be substantial underreporting of cases, particularly those with milder symptoms. By 26 February, relatively few cases have been reported among youth, with those 19 and under making up 2.4% of cases worldwide.
Government sources in Germany and the UK estimate that 60–70% of the population will need to become infected before effective herd immunity can be achieved.
Deaths
The time from development of symptoms to death has been between 6 and 41 days, with the most common being 14 days. By 21 March more than 11,400 deaths had been attributed to COVID-19. Most of those who have died were elderly—about 80% of deaths were in those over 60, and 75% had pre-existing health conditions including cardiovascular diseases and diabetes.
The first confirmed death was on 9 January 2020 in Wuhan. The first death outside China occurred on 1 February in the Philippines, and the first death outside Asia was in France on 14 February. By 28 February, outside mainland China, more than a dozen deaths each were recorded in Iran, South Korea, and Italy. By 13 March, over 40 countries and territories had reported deaths, on every continent except Antarctica.
The case-fatality rate (CFR) is the proportion of persons with a particular condition (cases) who die from that condition. During an epidemic, the death rate can be affected by quality of healthcare, general health and age profile of the population; while the CFR calculation needs to be adjusted to allow for possible under- or over-reporting of cases, and for the time lapse between infection and death. Estimates of the mortality rate by the World Health Organization are 3 to 4% as of 6 March 2020. Other estimates of the CFR vary from 1.4% to 2.3%.
Total confirmed deaths due to COVID-19 per million people, 20 March 2020.
Semi-log plot of cumulative incidence of confirmed cases and deaths in China and the rest of the world (ROW)
Semi-log plot of daily new confirmed cases by region: Hubei Province, mainland China excluding Hubei, the rest of the world (ROW), and the world total.
Signs and symptoms
Symptoms of COVID-19 are non-specific and those infected may either be asymptomatic or develop flu-like symptoms such as fever, cough, fatigue, shortness of breath, or muscle pain. The typical signs and symptoms and their prevalence are shown in the corresponding table. The Centers for Disease Control and Prevention (CDC) lists emergency symptoms including 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.
Further development of the disease can lead to severe pneumonia, acute respiratory distress syndrome, sepsis, septic shock and death. Some of those infected may be asymptomatic, returning test results that confirm infection but show no clinical symptoms, so researchers have issued advice that those with close contact to confirmed infected people should be closely monitored and examined to rule out infection. Chinese estimates of the asymptomatic ratio range from few to 44%.
The usual incubation period (the time between infection and symptom onset) ranges from one to fourteen days; it is most commonly five days. In one case, it may have had an incubation period of 27 days.
Transmission
The primary mode of transmission is via respiratory droplets that people exhale or cough. This is thought to occur when people are in close contact, often during coughing or sneezing. The European Centre for Disease Prevention and Control (ECDC) concur that it seems to spread via these droplets, but "[t]here is not enough epidemiological information at this time [23 March] to determine how easily and sustainably this virus spreads between people." The stability of the SARS-CoV-2 virus in the air and on various surfaces is believed to be comparable to that of other coronaviruses. A single study of how long SARS-CoV-2 (COVID-19) remains infectious on various surfaces, "show[s] that when the virus is carried by the droplets released when someone coughs or sneezes, it remains viable, or able to still infect people, in aerosols for at least three hours."
They also tested SARS-CoV-2 on plastic, stainless steel, copper, and cardboard, and found that although SARS-CoV-2 decayed exponentially over time in all five environments they tested, the virus was viable for infection for up to three days on plastic and stainless steel, for one day on cardboard, and for up to four hours on copper.
A survey of research on the inactivation of other coronaviruses using various biocidal agents suggests that disinfecting surfaces contaminated with SARS-CoV-2 may also be achieved using similar solutions (within one minute of exposure on a stainless steel surface), including 62–71% ethanol, 50–100% isopropanol, 0.1% sodium hypochlorite, 0.5% hydrogen peroxide, and 0.2–7.5% povidone-iodine; benzalkonium chloride and chlorhexidine gluconate are less effective.
The WHO has stated that the risk of spread from someone without symptoms is "very low". However, if someone has early symptoms and a mild cough, there is a risk of transmission. An analysis of infections in Singapore and Tianjin, China revealed that coronavirus infections may be spread by people who have recently caught the virus and have not yet begun to show symptoms, unlike other coronaviruses such as SARS.
Estimates of the basic reproduction number (the average number of people an infected person is likely to infect) range from 2.13 to 4.82. This is similar to the measure typical of severe acute respiratory syndrome-related coronavirus (SARS-CoV).
Virology
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel severe acute respiratory syndrome coronavirus, first isolated from three people with pneumonia connected to the cluster of acute respiratory illness cases in Wuhan. All features of the novel SARS-CoV-2 virus occur in related coronaviruses in nature.
SARS-CoV-2 is closely related to the original SARS-CoV. It is thought to have a zoonotic origin. Genetic analysis has revealed that the coronavirus genetically clusters with the genus Betacoronavirus, in subgenus Sarbecovirus (lineage B) together with two bat-derived strains. It is 96% identical at the whole genome level to other bat coronavirus samples (BatCov RaTG13). In February 2020, Chinese researchers found that there is only one amino acid difference in certain parts of the genome sequences between the viruses from pangolins and those from humans, however, whole genome comparison to date found at most 92% of genetic material shared between pangolin coronavirus and SARS-CoV-2, which is insufficient to prove pangolins to be the intermediate host.
Viral testing
The WHO has published several RNA testing protocols for SARS-CoV-2, with the first issued on 17 January. Testing uses real-time reverse transcription polymerase chain reaction (rRT-PCR). The test can be done on respiratory or blood samples. Results are generally available within a few hours to days.
A person is considered at risk if they have travelled to an area with ongoing community transmission within the previous 14 days, or have had close contact with an infected person. Common key indicators include fever, coughing and shortness of breath. Other possible indicators include fatigue, myalgia, anorexia, sputum production and sore throat.
Imaging
Characteristic imaging features on radiographs and computed tomography have been described in a limited case series. The Italian Radiological Society [it] is compiling an international online database of imaging findings for confirmed cases. Due to overlap with other infections such as adenovirus, imaging without confirmation by PCR is of limited use in identifying COVID-19. A larger comparing chest CT results to PCR has suggested that though imaging is less specific for the infection, it is significantly faster and more sensitive, suggesting that it may be considered as a screening tool in epidemic areas.
Prevention
Strategies for preventing transmission of the disease include overall good personal hygiene, hand washing, avoiding touching the eyes, nose or mouth with unwashed hands, coughing/sneezing into a tissue and putting the tissue directly into a dustbin. Those who may already have the infection have been advised to wear a surgical mask in public. Social distancing measures are also recommended to prevent transmission.
Many governments have restricted or advised against all non-essential travel to and from countries and areas affected by the outbreak. However, the virus has reached the stage of community spread in large parts of the world. This means that the virus is spreading within communities whose members have not traveled to areas with widespread transmission.
Health care providers taking care of someone who may be infected are recommended to use standard precautions, contact precautions and airborne precautions with eye protection. Contact tracing is an important method for health authorities to determine the source of an infection and to prevent further transmission. Misconceptions are circulating about how to prevent infection, for example: rinsing the nose and gargling with mouthwash are not effective. As of 13 March 2020, there is no COVID-19 vaccine, though a number of organizations are working to develop one.
The virus is typically spread from one person to another via respiratory droplets produced during coughing. It primarily spreads when people are in close contact but may also spread when one touches a contaminated surface and then their face. It is most contagious when people are symptomatic, although spread may be possible before symptoms appear. The time between exposure and symptom onset is typically around five days, but may range from two to fourteen days. Common symptoms include fever, cough, and shortness of breath. Complications may include pneumonia and acute respiratory distress syndrome. There is no vaccine or specific antiviral treatment. Primary treatment is symptomatic and supportive therapy. Recommended preventive measures include hand washing, covering the mouth when coughing, maintaining distance from other people, and monitoring and self-isolation for people who suspect they are infected.
Efforts to prevent the virus spreading include travel restrictions, quarantines, curfews, event postponements and cancellations, and facility closures. These include a quarantine of Hubei, nationwide quarantines in Italy and elsewhere in Europe, curfew measures elsewhere in China and South Korea, various border closures or incoming passenger restrictions, screening at airports and train stations, and travel advisories regarding regions with community transmission. Schools and universities have closed either on a nationwide or local basis in over 124 countries, affecting more than 1.2 billion students.
The pandemic has led to global socioeconomic disruption, the postponement or cancellation of sporting, religious, and cultural events, and widespread fears of supply shortages which have spurred panic buying. Misinformation and conspiracy theories about the virus have spread online, and there have been incidents of xenophobia and racism against Chinese and other East or Southeast Asian people.
Epidemiology
Health authorities in Wuhan, the capital of Hubei province, China, reported a cluster of pneumonia cases of unknown cause on 31 December 2019, and an investigation was launched in early January 2020. The cases mostly had links to the Huanan Seafood Wholesale Market and so the virus is thought to have a zoonotic origin. The virus that caused the outbreak is known as SARS-CoV-2, a newly discovered virus closely related to bat coronaviruses, pangolin coronaviruses and SARS-CoV.
The earliest person with symptoms was traced back to 1 December 2019, someone who did not have connections with the later cluster linked to the wet market. Of the early cluster of cases reported in December 2019, two-thirds were found to have a link with the market. On 14 March 2020, an unverified report from the South China Morning Post said that a 55-year-old from Hubei province could have been the first person who contracted the disease, on 17 November.
On 26 February 2020, the WHO reported that, as new cases reportedly dropped in China but suddenly increased in Italy, Iran, and South Korea, the number of new cases outside China had exceeded the number of new cases in China for the first time. There may be substantial underreporting of cases, particularly those with milder symptoms. By 26 February, relatively few cases have been reported among youth, with those 19 and under making up 2.4% of cases worldwide.
Government sources in Germany and the UK estimate that 60–70% of the population will need to become infected before effective herd immunity can be achieved.
Deaths
The time from development of symptoms to death has been between 6 and 41 days, with the most common being 14 days. By 21 March more than 11,400 deaths had been attributed to COVID-19. Most of those who have died were elderly—about 80% of deaths were in those over 60, and 75% had pre-existing health conditions including cardiovascular diseases and diabetes.
The first confirmed death was on 9 January 2020 in Wuhan. The first death outside China occurred on 1 February in the Philippines, and the first death outside Asia was in France on 14 February. By 28 February, outside mainland China, more than a dozen deaths each were recorded in Iran, South Korea, and Italy. By 13 March, over 40 countries and territories had reported deaths, on every continent except Antarctica.
The case-fatality rate (CFR) is the proportion of persons with a particular condition (cases) who die from that condition. During an epidemic, the death rate can be affected by quality of healthcare, general health and age profile of the population; while the CFR calculation needs to be adjusted to allow for possible under- or over-reporting of cases, and for the time lapse between infection and death. Estimates of the mortality rate by the World Health Organization are 3 to 4% as of 6 March 2020. Other estimates of the CFR vary from 1.4% to 2.3%.
Total confirmed deaths due to COVID-19 per million people, 20 March 2020.
Semi-log plot of cumulative incidence of confirmed cases and deaths in China and the rest of the world (ROW)
Semi-log plot of daily new confirmed cases by region: Hubei Province, mainland China excluding Hubei, the rest of the world (ROW), and the world total.
Signs and symptoms
Symptoms of COVID-19 are non-specific and those infected may either be asymptomatic or develop flu-like symptoms such as fever, cough, fatigue, shortness of breath, or muscle pain. The typical signs and symptoms and their prevalence are shown in the corresponding table. The Centers for Disease Control and Prevention (CDC) lists emergency symptoms including 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.
Further development of the disease can lead to severe pneumonia, acute respiratory distress syndrome, sepsis, septic shock and death. Some of those infected may be asymptomatic, returning test results that confirm infection but show no clinical symptoms, so researchers have issued advice that those with close contact to confirmed infected people should be closely monitored and examined to rule out infection. Chinese estimates of the asymptomatic ratio range from few to 44%.
The usual incubation period (the time between infection and symptom onset) ranges from one to fourteen days; it is most commonly five days. In one case, it may have had an incubation period of 27 days.
Transmission
The primary mode of transmission is via respiratory droplets that people exhale or cough. This is thought to occur when people are in close contact, often during coughing or sneezing. The European Centre for Disease Prevention and Control (ECDC) concur that it seems to spread via these droplets, but "[t]here is not enough epidemiological information at this time [23 March] to determine how easily and sustainably this virus spreads between people." The stability of the SARS-CoV-2 virus in the air and on various surfaces is believed to be comparable to that of other coronaviruses. A single study of how long SARS-CoV-2 (COVID-19) remains infectious on various surfaces, "show[s] that when the virus is carried by the droplets released when someone coughs or sneezes, it remains viable, or able to still infect people, in aerosols for at least three hours."
They also tested SARS-CoV-2 on plastic, stainless steel, copper, and cardboard, and found that although SARS-CoV-2 decayed exponentially over time in all five environments they tested, the virus was viable for infection for up to three days on plastic and stainless steel, for one day on cardboard, and for up to four hours on copper.
A survey of research on the inactivation of other coronaviruses using various biocidal agents suggests that disinfecting surfaces contaminated with SARS-CoV-2 may also be achieved using similar solutions (within one minute of exposure on a stainless steel surface), including 62–71% ethanol, 50–100% isopropanol, 0.1% sodium hypochlorite, 0.5% hydrogen peroxide, and 0.2–7.5% povidone-iodine; benzalkonium chloride and chlorhexidine gluconate are less effective.
The WHO has stated that the risk of spread from someone without symptoms is "very low". However, if someone has early symptoms and a mild cough, there is a risk of transmission. An analysis of infections in Singapore and Tianjin, China revealed that coronavirus infections may be spread by people who have recently caught the virus and have not yet begun to show symptoms, unlike other coronaviruses such as SARS.
Estimates of the basic reproduction number (the average number of people an infected person is likely to infect) range from 2.13 to 4.82. This is similar to the measure typical of severe acute respiratory syndrome-related coronavirus (SARS-CoV).
Virology
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel severe acute respiratory syndrome coronavirus, first isolated from three people with pneumonia connected to the cluster of acute respiratory illness cases in Wuhan. All features of the novel SARS-CoV-2 virus occur in related coronaviruses in nature.
SARS-CoV-2 is closely related to the original SARS-CoV. It is thought to have a zoonotic origin. Genetic analysis has revealed that the coronavirus genetically clusters with the genus Betacoronavirus, in subgenus Sarbecovirus (lineage B) together with two bat-derived strains. It is 96% identical at the whole genome level to other bat coronavirus samples (BatCov RaTG13). In February 2020, Chinese researchers found that there is only one amino acid difference in certain parts of the genome sequences between the viruses from pangolins and those from humans, however, whole genome comparison to date found at most 92% of genetic material shared between pangolin coronavirus and SARS-CoV-2, which is insufficient to prove pangolins to be the intermediate host.
Viral testing
The WHO has published several RNA testing protocols for SARS-CoV-2, with the first issued on 17 January. Testing uses real-time reverse transcription polymerase chain reaction (rRT-PCR). The test can be done on respiratory or blood samples. Results are generally available within a few hours to days.
A person is considered at risk if they have travelled to an area with ongoing community transmission within the previous 14 days, or have had close contact with an infected person. Common key indicators include fever, coughing and shortness of breath. Other possible indicators include fatigue, myalgia, anorexia, sputum production and sore throat.
Imaging
Characteristic imaging features on radiographs and computed tomography have been described in a limited case series. The Italian Radiological Society [it] is compiling an international online database of imaging findings for confirmed cases. Due to overlap with other infections such as adenovirus, imaging without confirmation by PCR is of limited use in identifying COVID-19. A larger comparing chest CT results to PCR has suggested that though imaging is less specific for the infection, it is significantly faster and more sensitive, suggesting that it may be considered as a screening tool in epidemic areas.
Prevention
Strategies for preventing transmission of the disease include overall good personal hygiene, hand washing, avoiding touching the eyes, nose or mouth with unwashed hands, coughing/sneezing into a tissue and putting the tissue directly into a dustbin. Those who may already have the infection have been advised to wear a surgical mask in public. Social distancing measures are also recommended to prevent transmission.
Many governments have restricted or advised against all non-essential travel to and from countries and areas affected by the outbreak. However, the virus has reached the stage of community spread in large parts of the world. This means that the virus is spreading within communities whose members have not traveled to areas with widespread transmission.
Health care providers taking care of someone who may be infected are recommended to use standard precautions, contact precautions and airborne precautions with eye protection. Contact tracing is an important method for health authorities to determine the source of an infection and to prevent further transmission. Misconceptions are circulating about how to prevent infection, for example: rinsing the nose and gargling with mouthwash are not effective. As of 13 March 2020, there is no COVID-19 vaccine, though a number of organizations are working to develop one.
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