# COVID-19 By [OCEM](https://paragraph.com/@moon24) · 2022-05-08 --- _"COVID" redirects here. For the ongoing pandemic, see_ [_COVID-19 pandemic_](https://en.wikipedia.org/wiki/COVID-19_pandemic)_. For other diseases caused by coronaviruses, see_ [_Coronavirus diseases_](https://en.wikipedia.org/wiki/Coronavirus_diseases)_._ _"Covid" redirects here. Not to be confused with_ [_Corvidae_](https://en.wikipedia.org/wiki/Corvidae)_._ Coronavirus disease 2019 (COVID-19)Other namesCOVID, (the) coronavirusTransmission and life-cycle of [SARS-CoV-2](https://en.wikipedia.org/wiki/SARS-CoV-2) causing COVID-19.Pronunciation * [/kəˈroʊnəvaɪrəs/](https://en.wikipedia.org/wiki/Help:IPA/English) * [/ˌkoʊvɪdnaɪnˈtiːn, ˌkɒvɪd-/](https://en.wikipedia.org/wiki/Help:IPA/English)[\[1\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-1) [Specialty](https://en.wikipedia.org/wiki/Medical_specialty)[Infectious disease](https://en.wikipedia.org/wiki/Infectious_disease_\(medical_specialty\))[Symptoms](https://en.wikipedia.org/wiki/Signs_and_symptoms)[Fever, cough, fatigue, shortness of breath, vomiting, loss of taste or smell; some cases asymptomatic](https://en.wikipedia.org/wiki/Symptoms_of_COVID-19)[\[2\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-CDC2020Sym-2)[\[3\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-WHO2020QA-3)[Complications](https://en.wikipedia.org/wiki/Complication_\(medicine\))[Pneumonia](https://en.wikipedia.org/wiki/Pneumonia), [viral sepsis](https://en.wikipedia.org/wiki/Viral_sepsis), [acute respiratory distress syndrome](https://en.wikipedia.org/wiki/Acute_respiratory_distress_syndrome), [kidney failure](https://en.wikipedia.org/wiki/Kidney_failure), [cytokine release syndrome](https://en.wikipedia.org/wiki/Cytokine_release_syndrome), [respiratory failure](https://en.wikipedia.org/wiki/Respiratory_failure), [pulmonary fibrosis](https://en.wikipedia.org/wiki/Pulmonary_fibrosis), [pediatric multisystem inflammatory syndrome](https://en.wikipedia.org/wiki/Pediatric_multisystem_inflammatory_syndrome), [long COVID](https://en.wikipedia.org/wiki/Long_COVID)Usual onset2–14 days (typically 5) from infectionDuration5 days to [chronic](https://en.wikipedia.org/wiki/Long_COVID)Causes[Severe acute respiratory syndrome coronavirus 2](https://en.wikipedia.org/wiki/Severe_acute_respiratory_syndrome_coronavirus_2) (SARS-CoV-2)[Diagnostic method](https://en.wikipedia.org/wiki/Medical_diagnosis)[rRT-PCR testing](https://en.wikipedia.org/wiki/Reverse_transcription_polymerase_chain_reaction), [CT scan](https://en.wikipedia.org/wiki/CT_scan), [Rapid antigen test](https://en.wikipedia.org/wiki/Rapid_antigen_test)PreventionFace coverings, [quarantine](https://en.wikipedia.org/wiki/Quarantine), physical/[social distancing](https://en.wikipedia.org/wiki/Social_distancing), ventilation, hand washing,[\[4\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-Talic2021-4) [vaccination](https://en.wikipedia.org/wiki/COVID-19_vaccine)[\[5\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-5)Treatment[Symptomatic and supportive](https://en.wikipedia.org/wiki/Management_of_COVID-19)Frequency516,781,042[\[6\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-JHU_ticker-6) confirmed casesDeaths6,249,649[\[6\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-JHU_ticker-6) Part of [a series](https://en.wikipedia.org/wiki/Category:COVID-19_pandemic) on the[COVID-19 pandemic](https://en.wikipedia.org/wiki/COVID-19_pandemic) * COVID-19 (disease) * [SARS-CoV-2](https://en.wikipedia.org/wiki/Severe_acute_respiratory_syndrome_coronavirus_2) (virus) * [Cases](https://en.wikipedia.org/wiki/COVID-19_pandemic_cases) * [Deaths](https://en.wikipedia.org/wiki/COVID-19_pandemic_deaths) show[Timeline](https://en.wikipedia.org/wiki/Timeline_of_the_COVID-19_pandemic) show[Locations](https://en.wikipedia.org/wiki/COVID-19_pandemic_by_country_and_territory) showInternational response showMedical response show[Variants](https://en.wikipedia.org/wiki/Variants_of_SARS-CoV-2) show[Economic impact](https://en.wikipedia.org/wiki/Economic_impact_of_the_COVID-19_pandemic) and [recession](https://en.wikipedia.org/wiki/COVID-19_recession) show[Impacts](https://en.wikipedia.org/wiki/Impact_of_the_COVID-19_pandemic)  [COVID-19 portal](https://en.wikipedia.org/wiki/Portal:COVID-19) * [v](https://en.wikipedia.org/wiki/Template:COVID-19_pandemic_sidebar) * [t](https://en.wikipedia.org/wiki/Template_talk:COVID-19_pandemic_sidebar) * [e](https://en.wikipedia.org/w/index.php?title=Template:COVID-19_pandemic_sidebar&action=edit) **Coronavirus disease 2019** (**COVID-19**) is a [contagious disease](https://en.wikipedia.org/wiki/Contagious_disease) caused by a virus, the [severe acute respiratory syndrome coronavirus 2](https://en.wikipedia.org/wiki/Severe_acute_respiratory_syndrome_coronavirus_2) (SARS-CoV-2). The first known case was [identified in Wuhan](https://en.wikipedia.org/wiki/COVID-19_pandemic_in_Hubei), China, in December 2019.[\[7\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-WSJ-20210226-7) The disease spread worldwide, leading to the [COVID-19 pandemic](https://en.wikipedia.org/wiki/COVID-19_pandemic).[\[8\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-NYT-20210226-8) [Symptoms of COVID‑19](https://en.wikipedia.org/wiki/Symptoms_of_COVID%E2%80%9119) are variable, but often include fever,[\[9\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-9) cough, headache,[\[10\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-10) fatigue, [breathing difficulties](https://en.wikipedia.org/wiki/Breathing_difficulties), [loss of smell](https://en.wikipedia.org/wiki/Anosmia), and [loss of taste](https://en.wikipedia.org/wiki/Ageusia).[\[11\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-11)[\[12\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-12)[\[13\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-13) Symptoms may begin one to fourteen days [after exposure](https://en.wikipedia.org/wiki/Incubation_period) to the virus. At least a third of people who are infected [do not develop noticeable symptoms](https://en.wikipedia.org/wiki/Asymptomatic).[\[14\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-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](https://en.wikipedia.org/wiki/Pneumonia)), while 14% develop severe symptoms ([dyspnea](https://en.wikipedia.org/wiki/Dyspnea), [hypoxia](https://en.wikipedia.org/wiki/Hypoxia_\(medical\)), or more than 50% lung involvement on imaging), and 5% suffer critical symptoms ([respiratory failure](https://en.wikipedia.org/wiki/Respiratory_failure), [shock](https://en.wikipedia.org/wiki/Shock_\(circulatory\)), or [multiorgan dysfunction](https://en.wikipedia.org/wiki/Organ_dysfunction)).[\[15\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-CDC_Interim_Guidance-15) [Older people](https://en.wikipedia.org/wiki/Older_people) are at a higher risk of developing severe symptoms. Some people continue to experience a range of effects ([long COVID](https://en.wikipedia.org/wiki/Long_COVID)) for months after recovery, and damage to organs has been observed.[\[16\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-:5-16) Multi-year studies are underway to further investigate the long-term effects of the disease.[\[16\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-:5-16) [COVID‑19 transmits](https://en.wikipedia.org/wiki/Transmission_of_COVID-19) when people breathe in air contaminated by droplets and small [airborne](https://en.wikipedia.org/wiki/Airborne_transmission) 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.[\[17\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-:23-17)[\[18\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-18) Several [COVID-19 testing](https://en.wikipedia.org/wiki/COVID-19_testing) methods have been developed to diagnose the disease. The standard diagnostic method is by detection of the virus's [nucleic acid](https://en.wikipedia.org/wiki/Nucleic_acid) by [real-time reverse transcription polymerase chain reaction](https://en.wikipedia.org/wiki/Reverse_transcription_polymerase_chain_reaction) (rRT-PCR), [transcription-mediated amplification](https://en.wikipedia.org/wiki/Transcription-mediated_amplification) (TMA), or by [reverse transcription loop-mediated isothermal amplification](https://en.wikipedia.org/wiki/Reverse_transcription_loop-mediated_isothermal_amplification) (RT-LAMP) from a [nasopharyngeal swab](https://en.wikipedia.org/wiki/Nasopharyngeal_swab). Several [COVID-19 vaccines](https://en.wikipedia.org/wiki/COVID-19_vaccine) have been approved and distributed in various countries, which have initiated [mass vaccination campaigns](https://en.wikipedia.org/wiki/Deployment_of_COVID-19_vaccines). Other [preventive measures](https://en.wikipedia.org/wiki/Pandemic_prevention) include [physical or social distancing](https://en.wikipedia.org/wiki/Social_distancing), [quarantining](https://en.wikipedia.org/wiki/Quarantine), ventilation of indoor spaces, covering coughs and sneezes, [hand washing](https://en.wikipedia.org/wiki/Hand_washing), and keeping unwashed hands away from the face. The [use of face masks or coverings](https://en.wikipedia.org/wiki/Face_masks_during_the_COVID-19_pandemic) has been recommended in public settings to minimize the risk of transmission. While work is underway to [develop drugs](https://en.wikipedia.org/wiki/COVID-19_drug_development) that inhibit the virus, the primary [treatment](https://en.wikipedia.org/wiki/Treatment_and_management_of_COVID-19) is symptomatic. Management involves the [treatment of symptoms](https://en.wikipedia.org/wiki/Symptomatic_treatment), [supportive care](https://en.wikipedia.org/wiki/Symptomatic_treatment), [isolation](https://en.wikipedia.org/wiki/Isolation_\(health_care\)), and [experimental measures](https://en.wikipedia.org/wiki/Medical_research). [Symptoms of COVID-19](https://en.wikipedia.org/wiki/Symptoms_of_COVID-19) are variable, ranging from mild symptoms to critical and possibly fatal illness.[\[34\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-Symptoms_of_COVID-19_CDC2020Sym-34)[\[35\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-Symptoms_of_COVID-19_Grant_et_al_2020-35) Common symptoms include [coughing](https://en.wikipedia.org/wiki/Cough), [fever](https://en.wikipedia.org/wiki/Fever), [loss of smell](https://en.wikipedia.org/wiki/Anosmia) (anosmia) and [taste](https://en.wikipedia.org/wiki/Ageusia) (ageusia), with less common ones including [headaches](https://en.wikipedia.org/wiki/Headache), [nasal congestion](https://en.wikipedia.org/wiki/Nasal_congestion) and [runny nose](https://en.wikipedia.org/wiki/Rhinorrhea), [muscle pain](https://en.wikipedia.org/wiki/Muscle_pain), [sore throat](https://en.wikipedia.org/wiki/Sore_throat), [diarrhea](https://en.wikipedia.org/wiki/Diarrhea), [eye irritation](https://en.wikipedia.org/wiki/Eye_irritation),[\[36\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-36) and toes swelling or turning purple,[\[37\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-37) and in moderate to severe cases [breathing difficulties](https://en.wikipedia.org/wiki/Breathing_difficulties).[\[38\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-Symptoms_of_COVID-19_ECDC-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](https://en.wikipedia.org/wiki/Sputum), [shortness of breath](https://en.wikipedia.org/wiki/Shortness_of_breath), and fever; a musculoskeletal symptom cluster with [muscle](https://en.wikipedia.org/wiki/Skeletal_muscle) and joint pain, headache, and fatigue; a cluster of digestive symptoms with abdominal pain, vomiting, and diarrhea.[\[38\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-Symptoms_of_COVID-19_ECDC-38) In people without prior ear, nose, and throat disorders, [loss of taste](https://en.wikipedia.org/wiki/Hypogeusia) combined with [loss of smell](https://en.wikipedia.org/wiki/Hyposmia) is associated with COVID-19 and is reported in as many as 88% of symptomatic cases.[\[39\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-Symptoms_of_COVID-19_Paderno_2020-39)[\[40\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-Symptoms_of_COVID-19_Chabot_2021-40)[\[41\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-Symptoms_of_COVID-19_pmid32483687-41) Of people who show symptoms, 81% develop only mild to moderate symptoms (up to mild [pneumonia](https://en.wikipedia.org/wiki/Pneumonia)), while 14% develop severe symptoms ([dyspnea](https://en.wikipedia.org/wiki/Dyspnea), [hypoxia](https://en.wikipedia.org/wiki/Hypoxia_\(medical\)), or more than 50% lung involvement on imaging) which requiring hospitalization and 5% of patients suffer critical symptoms ([respiratory failure](https://en.wikipedia.org/wiki/Respiratory_failure), septic [shock](https://en.wikipedia.org/wiki/Shock_\(circulatory\)), or [multiorgan dysfunction](https://en.wikipedia.org/wiki/Organ_dysfunction)) requiring ICU admission.[\[42\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-Symptoms_of_COVID-19_CDC_Interim_Guidance-42) At least a third of the people who are infected with the virus do not develop noticeable symptoms at any point in time.[\[43\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-43)[\[44\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-Symptoms_of_COVID-19_Asymptomatic-44) These [asymptomatic](https://en.wikipedia.org/wiki/Asymptomatic) carriers tend not to get tested and can still spread the disease.[\[44\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-Symptoms_of_COVID-19_Asymptomatic-44)[\[45\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-45)[\[46\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-46)[\[47\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-Symptoms_of_COVID-19_:2-47) Other infected people will develop symptoms later, called "pre-symptomatic", or have very mild symptoms and can also spread the virus.[\[47\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-Symptoms_of_COVID-19_:2-47) As is common with infections, there is [a delay](https://en.wikipedia.org/wiki/Incubation_period) between the moment a person first becomes infected and the appearance of the first symptoms. The [median](https://en.wikipedia.org/wiki/Median) delay for COVID-19 is four to five days[\[48\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-Symptoms_of_COVID-19_pmid32329974-48) possibly being infectious on 1-4 of those days.[\[49\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-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.[\[48\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-Symptoms_of_COVID-19_pmid32329974-48)[\[50\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-50) Most people recover from the [acute](https://en.wikipedia.org/wiki/Acute_\(medicine\)) phase of the disease. However, some people – over half of a [cohort](https://en.wikipedia.org/wiki/Cohort_study) of home-isolated young adults[\[51\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-51)[\[52\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-52) – continue to experience a range of effects, such as [fatigue](https://en.wikipedia.org/wiki/Fatigue), for months even after recovery, a condition called [long COVID](https://en.wikipedia.org/wiki/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.[\[53\]](https://en.wikipedia.org/wiki/COVID-19#cite_note-53) --- *Originally published on [OCEM](https://paragraph.com/@moon24/covid-19)*