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Coronavirus disease 2019 (COVID-19) is a contagious disease caused by a virus, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The first known case was identified in Wuhan, China, in December 2019.[7] The disease quickly spread worldwide, resulting in the COVID-19 pandemic.

Quick facts: Coronavirus disease 2019 (COVID-19), Other na...
Coronavirus disease 2019
Other namesCOVID, (the) coronavirus
Transmission and life-cycle of SARS-CoV-2 causing COVID-19.
SpecialtyInfectious disease
SymptomsFever, cough, fatigue, shortness of breath, vomiting, loss of taste or smell; some cases asymptomatic[2][3]
ComplicationsPneumonia, viral sepsis, acute respiratory distress syndrome, kidney failure, cytokine release syndrome, respiratory failure, pulmonary fibrosis, paediatric multisystem inflammatory syndrome, long COVID
Usual onset2–14 days (typically 5) from infection
Duration5 days to chronic
CausesSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2)
Diagnostic methodrRTPCR testing, CT scan, Rapid antigen test
PreventionVaccination,[4] face coverings, quarantine, physical/social distancing, ventilation, hand washing[5]
TreatmentSymptomatic and supportive
Frequency646,324,628[6] confirmed cases

Symptoms of COVID‑19 are variable, but often include fever,[8] cough, headache,[9] fatigue, breathing difficulties, loss of smell, and loss of taste.[10][11][12] 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.[13] 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 (dyspnoea, hypoxia, or more than 50% lung involvement on imaging), and 5% develop critical symptoms (respiratory failure, shock, or multiorgan dysfunction).[14] 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.[15] Multi-year studies are underway to further investigate the long-term effects of the disease.[15]

COVID‑19 transmits when people breathe air contaminated by droplets and small airborne particles containing the virus. The risk of breathing these 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.[16][17]

COVID-19 testing methods to detect the virus's nucleic acid include real-time reverse transcription polymerase chain reaction (rRTPCR),[18][19] transcription-mediated amplification,[18][19][20] and reverse transcription loop-mediated isothermal amplification (RTLAMP)[18][19] from a nasopharyngeal swab.[21]

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, use of face masks or coverings in public, covering coughs and sneezes, hand washing, and keeping unwashed hands away from the face. 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.