Coronavirus (COVID-19)

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Coronavirus (COVID-19)
Coronavirus Image.jpg
Image of the Coronavirus
Virus strain
  • 229E (alpha coronavirus)
  • NL63 (alpha coronavirus)
  • OC43 (beta coronavirus)
  • HKU1 (beta coronavirus)
  • MERS-CoV (the beta coronavirus Middle East Respiratory Syndrome, or MERS)
  • SARS-CoV (the beta coronavirus severe acute respiratory syndrome, or SARS)
  • SARS-CoV-2 (the novel coronavirus that causes coronavirus disease 2019, or COVID-19)
First case17 November 2019
OriginWuhan, China
Type
Virus
Confirmed cases2,992,501 Confirmed[1]
Deaths
206,878 deaths
Territories
Global

Last Updated: 26 April 2020 (this is no longer updated weekly)
Video Explaining Symptoms and Timeline of the Coronavirus
Global Infected = 2,992,501 Confirmed
Global Deaths = 206,878

Coronaviruses are a large group of viruses that cause diseases in animals and humans. They often circulate among camels, cats, and bats, and can sometimes evolve and infect people. In animals, coronaviruses can cause diarrhea in cows and pigs, and upper respiratory disease in chickens. In humans, the viruses can cause mild respiratory infections, like the common cold, but can lead to serious illnesses, like pneumonia. Coronaviruses are named for the crown-like spikes on their surface. Human coronaviruses were first identified in the mid-1960s. They are closely monitored by public health officials.

Epidemiology

Confirmed cases of the COVID-19 in the United States showing infected counties.
Microscopy image showing SARS-CoV-2. The spikes on the outer edge of the virus particles resemble a crown, giving the disease its characteristic name.
United States CDC, describing how to stop the spread of germs.
Common symptoms of the Novel Coronavirus.
The Power of Social Distancing.

A cluster of pneumonia cases of unknown cause was reported by health authorities in Wuhan, the capital of Hubei province, China on 31 December 2019 and an investigation was launched in early January 2020. These cases mostly had links to the Huanan Seafood Wholesale Market, which also sold live animals; consequently, the virus is thought to have a zoonotic origin. The virus that caused the outbreak is known as SARS-CoV-2, a new virus closely related to bat coronaviruses, pangolin coronaviruses and SARS-CoV. It is believed that the virus possibly originated in horseshoe bats (genus Rhinolophus).

The earliest person with symptoms was traced back to 17 November 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 under-reporting of cases, particularly among those with milder symptoms. Reported numbers may also reflect local decisions on whom and when to test. As an example, on 13 March 2020, the UK reported 798 confirmed cases, but health officials estimated the actual number of people infected was probably between 5,000 and 10,000. As of 26 February, "very few" cases have been reported among youth. A report from the WHO noted that those 19 and under made up just 2.4 percent of cases worldwide.

Deaths

Among those who died from the disease, the time from development of symptoms to death was between 6 and 41 days, with a median of 14 days. As of 18 March 2020, more than 8,200 deaths have been attributed to COVID-19. According to China's NHC, most of those who 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. By 28 February, outside mainland China, more than a dozen deaths were recorded in each of Iran, South Korea and Italy. By 13 March, over 40 countries and territories had reported deaths, on every continent except Antarctica.

Contagion and Transmission

The primary mode of transmission is via respiratory droplets that people exhale, for example when coughing or sneezing. Droplets stay suspended in the air for only a short time but may stay viable and contagious on a metal, glass or plastic surface.[2] 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, some of which can survive for up to nine days at room temperature.

Its similarity to SARS-CoV-1 in particular was confirmed in laboratory tests that found both viruses could survive up to or beyond 72 hours on plastic and stainless steel. A survey of research on the inactivation other coronaviruses using various biocidal agents suggests that disinfecting surfaces contaminated with SARS-CoV-2 may also be achieved using similar solutions, including 62–71% ethanol, 50–100% isopropanol, 0.1% sodium hypochlorite (after one minute), 0.5% hydrogen peroxide, and 0.2–7.5% povidone-iodine; benzalkonium chloride and chlorhexidine gluconate are less effective.

The World Health Organization has stated that the risk of spread from someone without symptoms is "very low". However, if someone has beginning symptoms and a mild cough, there is a risk of transmission. There have been estimates for the basic reproduction number (the average number of people an infected person is likely to infect), ranging from 2.13 to 4.82. This is similar to 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. 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.[3] 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 genome sequences between the viruses found in 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.

Diagnosis

Infection by the virus can be provisionally diagnosed on the basis of symptoms, though confirmation is ultimately by reverse transcription polymerase chain reaction (rRT-PCR) of infected secretions (71% sensitivity) and CT Imaging (98% sensitivity).[4][5]

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).[6] 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 traveled 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.[7] Characteristic imaging features on radiographs and computed tomography]have been described in a limited case series.However, due to overlap with other infections such as adenovirus, imaging without confirmation by PCR is of limited use in identifying COVID-19.

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.

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 travelled 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 18 March 2020, there is no COVID-19 vaccine though a number of organizations are working to develop one.

Hand washing

Hand washing is recommended to prevent the spread of the disease. it is recommended that people wash hands often with soap and water for at least 20 seconds, especially after going to the toilet or when hands are visibly dirty; before eating; and after blowing one's nose, coughing, or sneezing. It further recommended using an alcohol-based hand sanitizer with at least 60% alcohol by volume when soap and water are not readily available.<

Respiratory Hygiene

Health organizations recommended that people cover their mouth and nose with a bent elbow or a tissue when coughing or sneezing (the tissue should then be disposed of immediately). The use of surgical masks by those who may be infected has been recommended, as they can limit the volume and travel distance of expiratory droplets dispersed when talking, sneezing and coughing. Masks have also been recommended for use by those taking care of someone who may have the disease. Masks are not recommended for most people. There is limited evidence that the wearing of surgical masks by uninfected people at low risk is effective, although they may help people avoid touching their face. Surgical masks are the lowest grade of protection, and are designed mainly to protect others from the wearer. Masks designed to protect the wearer are technically "respirators", though calling them "masks" is common.

Social Distancing

Social distancing includes infection control actions intended to slow the spread of disease by minimizing close contact between individuals. Methods include quarantines; travel restrictions; and the closing of schools, workplaces, stadiums, theatres, or shopping centres. Individuals may also apply social distancing methods by staying at home, limiting travel, avoiding crowded areas, not shaking hands, and physically distancing themselves from others. Many governments are now mandating or recommending social distancing in regions affected by the outbreak. Older adults and those with serious chronic conditions face increased risk of serious illness and complications and have been advised by the US CDC to avoid crowds and stay home as much as possible in areas of community outbreak.

Self-Isolation

Self-isolation at home has been recommended for those diagnosed with COVID-19 and those who suspect they have been infected. Additionally, individuals who have recently traveled to a country with widespread transmission or who have been in direct contact with someone diagnosed with COVID-19 have also been asked by some government health agencies to self-quarantine or practice social distancing for 14 days from the time of last possible exposure. It is recommended that those with symptoms of COVID-19 should stay at home for 14 days, taking precautions to avoid infecting others within the household. As long as symptoms don't significantly worsen health services should not be contacted.

Containment

Efforts to prevent spread have included travel restrictions, quarantines, curfews, event postponements and cancellations, and facility closures. These include a quarantine of Hubei, the nationwide quarantines of Italy, Spain, France, the Czech Republic, and Germany, curfew measures in China and South Korea, various border closures or incoming passenger restrictions,screening methods 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 at least 115 countries, affecting more than 950 million students. Effects of the pandemic include social and economic instability, the postponement or cancellation of sporting and cultural events, the suspension of in-person religious services, xenophobia and racism against Chinese, East and Southeast Asian people as well as the online spread of misinformation and conspiracy theories about the virus.

Further Reading

References

  1. World Health Organization (17 March 2020). Coronavirus disease 2019 (COVID-19) Situation Report – 57. Received from: https://www.who.int/docs/default-source/coronaviruse/situation-reports/20200317-sitrep-57-covid-19.pdf?sfvrsn=a26922f2_4
  2. Bai, Y., Yao, L., Wei, T., Tian, F., Jin, D. Y., Chen, L., & Wang, M. (2020). Presumed asymptomatic carrier transmission of COVID-19. Jama.
  3. Liu, Y., Gayle, A. A., Wilder-Smith, A., & Rocklöv, J. (2020). The reproductive number of COVID-19 is higher compared to SARS coronavirus. Journal of travel medicine.
  4. Pan, F., Ye, T., Sun, P., Gui, S., Liang, B., Li, L., ... & Zheng, C. (2020). Time course of lung changes on chest CT during recovery from 2019 novel coronavirus (COVID-19) pneumonia. Radiology, 200370.
  5. Bernheim, A., Mei, X., Huang, M., Yang, Y., Fayad, Z. A., Zhang, N., ... & Li, S. (2020). Chest CT findings in coronavirus disease-19 (COVID-19): Relationship to duration of infection. Radiology, 200463.
  6. World Health Organization. (2020). Laboratory testing for coronavirus disease 2019 (COVID-19) in suspected human cases: interim guidance, 2 March 2020 (No. WHO/COVID-19/laboratory/2020.4). World Health Organization.
  7. Xu, Z., Shi, L., Wang, Y., Zhang, J., Huang, L., Zhang, C., ... & Tai, Y. (2020). Pathological findings of COVID-19 associated with acute respiratory distress syndrome. The Lancet Respiratory Medicine.