COVID-19 and the SARS-CoV-2 virus

COVID-19 is a contagious disease caused by the SARS-CoV-2 coronavirus, which led to a global pandemic starting in January 2020. Symptoms vary and can include fever, fatigue, cough, breathing difficulties, and loss of taste or smell, typically appearing one to fourteen days after exposure.

While approximately one-third of infected individuals do not develop noticeable symptoms, those who do may experience varying levels of severity. Most patients (81%) develop mild to moderate symptoms, 14% develop severe symptoms such as hypoxia, and 5% experience critical symptoms including respiratory failure or organ dysfunction. Older populations face a higher risk of severe illness.

Transmission occurs through infectious particles inhaled via the air or through contact with contaminated surfaces and mucous membranes. The virus can remain suspended in the air, particularly indoors. Individuals can remain contagious for up to 20 days and may spread the virus even without showing symptoms. Some patients experience long-term effects known as long COVID, which can involve organ damage.