COVID-19 overview: symptoms, transmission and vaccine info

COVID-19 is a contagious disease caused by the SARS‑CoV‑2 coronavirus that spread worldwide from January 2020, triggering a global pandemic. Typical symptoms include fever, fatigue, cough, breathing difficulty, loss of smell and taste, though about one‑third of infections are asymptomatic. Among symptomatic patients, roughly 81% experience mild to moderate illness, 14% develop severe disease with significant lung involvement, and 5% become critically ill, especially older adults.

Transmission occurs primarily through inhalation of infectious aerosols and contact with contaminated surfaces, with the virus remaining airborne for extended periods indoors. People can remain contagious for up to 20 days, even without symptoms. Diagnostic testing relies on nucleic‑acid methods such as RT‑PCR, transcription‑mediated amplification and RT‑LAMP from nasopharyngeal samples. Several vaccines have received approval and are being deployed globally, while preventive measures include physical distancing, mask use, ventilation, hand hygiene and isolation of cases.