"Covid" redirects here. Not to be confused with Corvidae.Coronavirus disease 2019(COVID-19)Other namesCOVID, (the) coronavirus
Transmission and life-cycle of SARS-CoV-2 causing COVID-19.Pronunciation[1] SpecialtyInfectious diseaseSymptomsFever, cough, fatigue, shortness of breath, vomiting, loss of taste or smell; some cases asymptomatic[2][tiga]ComplicationsPneumonia, viral sepsis, acute respiratory distress syndrome, kidney failure, cytokine release syndrome, respiratory failure, pulmonary fibrosis, pediatric multisystem inflammatory syndrome, long COVIDUsual onset2–14 days (typically lima) from infectionDuration5 days to chronicCausesSevere acute respiratory syndrome coronavirus dua (SARS-CoV-2)Diagnostic methodrRT-PCR testing, CT scan, Rapid antigen testPreventionVaccination,[4] face coverings, quarantine, physical/social distancing, ventilation, hand washing[lima]TreatmentSymptomatic and supportiveFrequency528,753,708[6] confirmed casesDeaths6,287,392[6]
Coronavirus disease 2019 (COVID-19) is a contagious disease caused by a virus, the severe acute respiratory syndrome coronavirus dua (SARS-CoV-2). The first known case was identified in Wuhan, China, in December 2019.[7] The disease spread worldwide, leading to the COVID-19 pandemic.[8]
Symptoms of COVID‑19 are variable, but often include fever,[9] cough, headache,[10] fatigue, breathing difficulties, loss of smell, and loss of taste.[11][12][13] Symptoms may begin one to fourteen days after exposure to the virus. At least a third of people who are infected do not develop noticeable symptoms.[14] Of those people who develop symptoms noticeable enough to be classed as patients, most (81%) develop mild to moderate symptoms (up to mild pneumonia), while 14% develop severe symptoms (dyspnea, hypoxia, or more than 50% lung involvement on imaging), and 5% develop critical symptoms (respiratory failure, shock, or multiorgan dysfunction).[15] Older people are at a higher risk of developing severe symptoms. Some people continue to experience a range of effects (long COVID) for months after recovery, and damage to organs has been observed.[16] Multi-year studies are underway to further investigate the long-term effects of the disease.[16]
COVID‑19 transmits when people breathe in air contaminated by droplets and small airborne particles containing the virus. The risk of breathing these in is highest when people are in close proximity, but they can be inhaled over longer distances, particularly indoors. Transmission can also occur if splashed or sprayed with contaminated fluids in the eyes, nose or mouth, and, rarely, via contaminated surfaces. People remain contagious for up to 20 days, and can spread the virus even if they do not develop symptoms.[17][18]
Several COVID-19 testing methods have been developed to diagnose the disease. The standard diagnostic method is by detection of the virus's nucleic acid by real-time reverse transcription polymerase chain reaction (rRT-PCR), transcription-mediated amplification (TMA), or by reverse transcription loop-mediated isothermal amplification (RT-LAMP) from a nasopharyngeal swab.
Several COVID-19 vaccines have been approved and distributed in various countries, which have initiated mass vaccination campaigns. Other preventive measures include physical or social distancing, quarantining, ventilation of indoor spaces, covering coughs and sneezes, hand washing, and keeping unwashed hands away from the face. The use of face masks or coverings has been recommended in public settings to minimize the risk of transmission. While work is underway to develop drugs that inhibit the virus, the primary treatment is symptomatic. Management involves the treatment of symptoms, supportive care, isolation, and experimental measures.Nomenclature
During the initial outbreak in Wuhan, the virus and disease were commonly referred to as "coronavirus" and "Wuhan coronavirus",[19][20][21] with the disease sometimes called "Wuhan pneumonia".[22][23] In the past, many diseases have been named after geographical locations, such as the Spanish flu,[24] Middle East respiratory syndrome, and Zika virus.[25] In January 2020, the World Health Organization (WHO) recommended 2019-nCoV[26] and 2019-nCoV acute respiratory disease[27] as interim names for the virus and disease per 2015 guidance and international guidelines against using geographical locations or groups of people in disease and virus names to prevent social cacat.[28][29][30] The official names COVID‑19 and SARS-CoV-dua were issued by the WHO on 11 February 2020.[31] The Director-General, Tedros Adhanom explained that CO stands for corona, VI for virus, D for disease, and 19 for 2019, the year in which the outbreak was first identified.[32] The WHO additionally uses "the COVID‑19 virus" and "the virus responsible for COVID‑19" in public communications.[31][33]Signs and symptoms
The symptoms of COVID-19 are variable, ranging from mild symptoms to critical and possibly fatal illness.[34][35] Common symptoms include coughing, fever, loss of smell (anosmia) and taste (ageusia), with less common ones including headaches, nasal congestion and runny nose, muscle pain, sore throat, diarrhea, eye irritation,[36] and toes swelling or turning purple,[37] and in moderate to severe cases breathing difficulties.[38] People with the COVID-19 infection may have different symptoms, and their symptoms may change over time. Three common clusters of symptoms have been identified: one respiratory symptom cluster with cough, sputum, shortness of breath, and fever; a musculoskeletal symptom cluster with muscle and joint pain, headache, and fatigue; a cluster of digestive symptoms with abdominal pain, vomiting, and diarrhea.[38] In people without prior ear, nose, and throat disorders, loss of taste combined with loss of smell is associated with COVID-19 and is reported in as many as 88% of symptomatic cases.[39][40][41]
Of people who show symptoms, 81% develop only mild to moderate symptoms (up to mild pneumonia), while 14% develop severe symptoms (dyspnea, hypoxia, or more than 50% lung involvement on imaging) which requiring hospitalization and 5% of patients suffer critical symptoms (respiratory failure, septic shock, or multiorgan dysfunction) requiring ICU admission.[42] At least a third of the people who are infected with the virus do not develop noticeable symptoms at any point in time.[43][44] These asymptomatic carriers tend not to get tested and can still spread the disease.[44][45][46][47] Other infected people will develop symptoms later, called "pre-symptomatic", or have very mild symptoms and can also spread the virus.[47]
As is common with infections, there is a delay between the moment a person first becomes infected and the appearance of the first symptoms. The median delay for COVID-19 is four to five days[48] possibly being infectious on 1-4 of those days.[49] Most symptomatic people experience symptoms within two to seven days after exposure, and almost all will experience at least one symptom within 12 days.[48][50]
Most people recover from the acute phase of the disease. However, some people – over half of a cohort of home-isolated young adults[51][52] – continue to experience a range of effects, such as fatigue, for months even after recovery, a condition called long COVID; long-term damage to organs has been observed. Multi-year studies are underway to further investigate the potential long-term effects of the disease.[53]Cause
COVID‑19 is caused by infection with a strain of coronavirus known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).[54]Transmission
The respiratory route of spread of COVID-19, encompassing larger droplets and aerosols.
COVID-19 is mainly transmitted when people breathe in air contaminated by droplets/aerosols and small airborne particles containing the virus. Infected people exhale those particles as they breathe, talk, cough, sneeze, or sing.[55][56][57][58] Transmission is more likely the more physically close people are. However, infection can occur over longer distances, particularly indoors.[55][59]
Infectivity can begin four to five days before the onset of symptoms,[60] although contact tracing typically begins only two to three days before symptom onset.[61] Infected people can spread the disease even if they are pre-symptomatic or asymptomatic.[61]Most commonly, the peak viral load in upper respiratory tract samples occurs close to the time of symptom onset and declines after the first week after symptoms begin.[61] Current evidence suggests a duration of viral shedding and the period of infectiousness of up to ten days following symptom onset for people with mild to moderate COVID-19, and a up to 20 days for persons with severe COVID-19, including immunocompromised people.[62][61]
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