Coronavirus disease 2019
Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The disease was first identified in 2019 in Wuhan, China, and has since spread globally, resulting in the 2019–20 coronavirus pandemic. Common symptoms include fever, cough and shortness of breath. Muscle pain, sputum production and sore throat are less common. While the majority of cases result in mild symptoms, some progress to severe pneumonia and multi-organ failure. The rate of deaths per number of diagnosed cases is estimated to be 3.4% but varies by age and other health conditions.
The infection is typically spread from one person to another via respiratory droplets produced during coughing and sneezing. Time from exposure to onset of symptoms is generally between two and 14 days, with an average of five days. The standard method of diagnosis is by reverse transcription polymerase chain reaction (rRT-PCR) from a nasopharyngeal swab or throat swab. The infection can also be diagnosed from a combination of symptoms, risk factors and a chest CT scan showing features of pneumonia.
Recommended measures to prevent the disease include frequent hand washing, maintaining distance from others, and not touching one's face. The use of masks is recommended for those who suspect they have the virus and their caregivers but not the general public. There is no vaccine or specific antiviral treatment for COVID-19. Management involves treatment of symptoms, supportive care, isolation and experimental measures.
The World Health Organization (WHO) declared the 2019–20 coronavirus outbreak a pandemic and a Public Health Emergency of International Concern (PHEIC). Evidence of local transmission of the disease has been found in many countries across all six WHO regions.
Those infected with the virus may either be asymptomatic or develop flu-like symptoms that include fever, cough and shortness of breath. Diarrhoea and upper respiratory symptoms such as sneezing, runny nose, or sore throat are less common. Cases can progress to pneumonia, multi-organ failure and death in the most vulnerable.
The incubation period ranges from two to 14 days, with an estimated median incubation period of five to six days, according to the World Health Organization (WHO). The median time from onset to clinical recovery for mild cases is approximately 2 weeks and is 3–6 weeks for people with severe or critical disease. Preliminary data suggests that the time period from onset to the development of severe disease, including hypoxia, is 1 week. Among people who have died, the time from symptom onset to outcome ranges from 2–8 weeks.
One study in China found that CT scans showed ground-glass opacities in 56%, but 18% had no radiological findings. 5% were admitted to intensive care units, 2.3% needed mechanical support of ventilation and 1.4% died. Bilateral and peripheral ground glass opacities are the most typical CT findings. Consolidation, linear opacities and reverse halo sign are other radiological findings. Initially, the lesions are confined to one lung, but as the disease progresses, indications manifest in both lungs in 88% of so-called "late patients" in the study group (the subset for whom time between onset of symptoms and chest CT was 6–12 days).
It has been noted that children seem to have milder symptoms than adults.