Coronavirus disease 2019 (COVID-19) is a contagious respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a specific type of coronavirus, responsible for an ongoing pandemic.
Common symptoms include fever, cough, fatigue, breathing difficulties, and loss of smell and taste. Symptoms begin one to fourteen days after exposure to the virus. While most people have mild symptoms, some people develop acute respiratory distress syndrome (ARDS) possibly precipitated by cytokine storm, multi-organ failure, septic shock, and blood clots. Longer-term damage to organs (in particular, the lungs and heart) has been observed, and there is concern about a significant number of patients who have recovered from the acute phase of the disease but continue to experience a range of effects—including severe fatigue, memory loss and other cognitive issues, low grade fever, muscle weakness, breathlessness, and other symptoms—for months afterwards.
COVID-19 mainly spreads through the air when people are near each other, primarily via small droplets or aerosols, as an infected person breathes, coughs, sneezes, sings, or speaks. Transmission via contaminated surfaces has not been conclusively demonstrated, and the main mode of transmission is suspected to be airborne. It can spread from an infected person for up to two days before symptoms appear (presymptomatic), and from those who do not show any (asymptomatic). People remain infectious for up to ten days in moderate cases, and two weeks in severe cases. The standard diagnosis method is by real-time reverse transcription polymerase chain reaction (rRT-PCR) from a nasopharyngeal swab.
Preventive measures include social distancing, quarantine, 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 minimise the risk of transmissions.
There are no proven vaccines or specific treatments for COVID-19 yet, though several are in development. Management involves the treatment of symptoms, supportive care, isolation, and experimental measures.
Signs and symptoms
Some symptoms of COVID-19 can be relatively non-specific; the two most common symptoms are fever (88 percent) and dry cough (68 percent). Among those who develop symptoms, approximately one in five may become more seriously ill and have difficulty breathing. Emergency symptoms include difficulty breathing, persistent chest pain or pressure, sudden confusion, difficulty waking, and bluish face or lips; immediate medical attention is advised if these symptoms are present. Further development of the disease can lead to complications including pneumonia, acute respiratory distress syndrome, sepsis, septic shock, and kidney failure.
As is common with infections, there is a delay, known as the incubation period, between the moment a person first becomes infected and the appearance of the first symptoms. The median incubation period for COVID-19 is four to five days. Most symptomatic people experience symptoms within two to seven days after exposure, and almost all symptomatic people will experience one or more symptoms before day twelve.