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. While approximately one-third of infected individuals do not develop noticeable symptoms, most patients (81%) experience mild to moderate symptoms. About 14% develop severe symptoms such as hypoxia, and 5% face critical complications including respiratory failure or multiorgan dysfunction.

Transmission occurs through infectious particles inhaled or through contact with the eyes, nose, or mouth. The risk is elevated in close proximity or when small airborne particles remain suspended in indoor air. Individuals can remain contagious for up to 20 days. Long-term effects, known as long COVID, can persist for months or years and may involve organ damage.