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 on average 3.4%, ranging from 0.2% in those less than 20 to approximately 15% in those over 80 years old.

These percentage figures do not take into account unconfirmed cases, which would be significantly lower. 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.

Source: Wikipedia: https://en.wikipedia.org/wiki/Coronavirus_disease_2019