COVID-19 disease overview: symptoms, transmission, testing and vaccination

COVID-19 is a contagious disease caused by the SARS‑CoV‑2 virus that spread worldwide from January 2020, leading to a global pandemic. Most infected persons develop mild to moderate illness, while about 14 % experience severe respiratory problems and roughly 5 % become critically ill. Older individuals are at higher risk, and a significant proportion of infections remain asymptomatic.

The virus spreads mainly through inhalation of airborne particles, especially in close indoor settings, but can also be transmitted via contaminated surfaces. Testing methods include real‑time RT‑PCR, transcription‑mediated amplification and RT‑LAMP from nasopharyngeal samples. Multiple vaccines have been approved and are being distributed globally, complemented by preventive actions such as physical distancing, mask use, ventilation, hand hygiene and isolation of cases.