A newly identified coronavirus, provisionally termed 2019-nCoV (an acronym for 2019 novel coronavirus) and subsequently named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged in central China in November 2019. The disease caused by this virus has been called COVID-19 (an acronym for coronavirus disease 2019). The infectious virus initially affected individuals in the city of Wuhan, predominantly those working at or frequenting certain animal markets. At first, the virus was thought to spread from animals (possibly bats or pangolins) to people. However, affected individuals who did not have exposure to any animal markets were subsequently identified, indicating that person-to-person transmission was occurring. In addition, some studies indicate that the virus remains stable for several hours to days in aerosols and on surfaces; thus, individuals may be acquiring the virus either via the air or after touching contaminated objects. Because of the many unknowns concerning this novel coronavirus and the rapidity with which it is spreading, health professionals and epidemiologists are extremely concerned. On January 30, 2020, the World Health Organization declared COVID-19 to be a global health emergency. On March 11, 2020, the World Health Organization officially announced that COVID-19 is a pandemic (worldwide epidemic). See also: Animal virus; Coronavirus; Disease ecology; Epidemic; Epidemiology; Infectious disease; Virus; Virus classification
Coronaviruses comprise a major group of common animal viruses that typically infect mammals and birds. The name coronavirus (Latin corona, meaning crown or a halo appearance) comes from the shape of the virus when the virus is observed using an electron microscope. Fewer than ten coronaviruses have been determined to cause disease in humans. In the twenty-first century, though, a few emergent coronaviruses have resulted in serious and contagious diseases—especially pneumonia or other respiratory illnesses—in humans. Two of the most significant coronavirus diseases are severe acute respiratory syndrome (SARS), which was initially reported in Asia in 2003 and affected more than 8000 people (with 774 deaths), and Middle East respiratory syndrome (MERS), which was first reported in Saudi Arabia in 2012 and affected more than 2500 individuals (including at least 860 deaths). See also: Middle East respiratory syndrome (MERS); Severe acute respiratory syndrome (SARS)
Due to the ease and rapidity of air travel, COVID-19 cases have been reported in almost all countries across the world. As of late September 2020, COVID-19 has been confirmed in more than 32,235,000 persons worldwide, and approximately 983,000 people have died. More than 90,000 individuals have been reported as infected in China, including more than 4700 deaths (however, these numbers are likely to be much higher than reported). As a result of quarantines and restrictions of personal movement, though, the pace of infection in China has slowed dramatically, and now other countries account for the majority of cases. As of late September 2020, the United States leads the world in the number of confirmed coronavirus cases (more than 6,980,000 cases, including over 203,000 deaths). In addition, the numbers of deaths are significant in Brazil (more than 140,000 deaths), India (more than 92,000 deaths), Mexico (more than 75,400 deaths), the United Kingdom (more than 41,990 deaths), Italy (more than 35,780 deaths), Peru (more than 31,870 deaths), and France (more than 31,500 deaths). As a result, many countries have ordered lockdowns and closed their borders, and individuals (especially those persons most at risk, such as the elderly) have been encouraged to self-quarantine. Urgent emergency measures are being implemented across the United States, throughout Europe, and elsewhere in attempts to halt the pace of community spreading of the virus. Furthermore, outbreaks have been detected on a number of cruise ships, creating logistical difficulties. Importantly, multiple airlines have temporarily suspended many international flights to highly infected areas due to the coronavirus outbreak. Overall, airlines are adopting a series of measures to prevent the spread of the deadly disease. See also: Pneumonia; Respiratory system disorders
Individuals infected by COVID-19 have displayed a wide spectrum of symptoms, ranging from mild cold- or flu-like illness to severe respiratory distress and even death. Typical symptoms include cough, fever, shortness of breath, and breathing difficulties. Although further determinations are necessary, symptoms have appeared in as few as 2 days or as long as 14 days after exposure to the coronavirus. This range is similar to that observed for the incubation period of MERS viruses. However, COVID-19 is not the same as the coronavirus that causes either MERS or SARS. Despite this, preliminary genetic analyses suggest that the new virus emerged from a virus related to SARS. See also: Detection of respiratory viruses; Genetics
The chance of contracting COVID-19 is low for individuals who are not located in an area where COVID-19 is spreading, or for those who have not traveled from one of those areas or have not been in close contact with someone who has and is feeling unwell. The risk becomes more serious for those who are located in an area where an outbreak of COVID-19 is occurring. Such individuals should follow advice issued by national and local health authorities. Although COVID-19 causes only mild illness for most people, the virus can make some people very ill. More rarely, the disease can be fatal. Older people, and those with preexisting medical conditions (such as high blood pressure, heart problems, or diabetes), appear to be more vulnerable. Standard recommendations to prevent the spread of infection include regular hand washing, and covering mouth and nose when coughing and sneezing. Avoidance of close contact with anyone showing symptoms of respiratory illness, especially coughing and sneezing, is important as well.
There is currently neither a vaccine nor any specific antiviral therapy to prevent or treat COVID-19 infection. The only proven methodology to prevent infection is to avoid being exposed to the virus; thus, uninfected individuals (except for properly protected health-care professionals) need to avoid contact with afflicted persons. In general, those infected with COVID-19 should receive supportive treatment based on their clinical presentation—that is, to help relieve symptoms in relatively mild cases or to ensure respiratory function in the most severe cases. See also: Critical care medicine