COVID-19: Global disease characteristics and prevention measures

COVID-19 is a contagious illness caused by the SARS‑CoV‑2 coronavirus that spread worldwide after January 2020, leading to a pandemic. Typical symptoms include fever, fatigue, cough, breathing difficulty, loss of smell and taste, and many infections are asymptomatic. Among confirmed patients, about 81 % experience mild to moderate illness, 14 % develop severe disease requiring oxygen support, and roughly 5 % become critical with respiratory failure or organ dysfunction, especially older adults.

The virus spreads mainly through inhaled droplets and aerosols, with transmission possible in close contact and via contaminated surfaces. People can remain contagious for up to 20 days, even without symptoms. Diagnostic methods rely on nucleic‑acid detection such as RT‑PCR, transcription‑mediated amplification, and RT‑LAMP from nasopharyngeal swabs. Multiple vaccines have been approved and are being administered globally, alongside non‑pharmaceutical measures like physical distancing, mask‑wearing, ventilation, hand hygiene, and quarantine to curb transmission.

While many patients recover with supportive care, long‑COVID effects and organ damage have been observed in a subset, prompting ongoing studies of long‑term outcomes.