COVID‑19: Global disease profile, symptoms, transmission and vaccines

COVID‑19 is a contagious disease caused by the SARS‑CoV‑2 virus. The outbreak spread worldwide beginning in January 2020, leading to a global pandemic. Typical symptoms include fever, fatigue, cough, breathing difficulty, loss of smell and taste, with an incubation period of one to fourteen days. About one‑third of infections are asymptomatic. Among those who develop symptoms, roughly 81 % experience mild to moderate illness, 14 % develop severe disease, and 5 % become critical; older adults face higher risk of severe outcomes and death. Some patients suffer long‑term effects known as “long COVID.”

Transmission occurs mainly through respiratory droplets and aerosol particles, especially indoors, and can also happen via contaminated surfaces. Infected individuals may remain contagious for up to 20 days, even without symptoms. Diagnosis relies on nucleic‑acid tests such as RT‑PCR, transcription‑mediated amplification and RT‑LAMP. Multiple vaccines have received approval and are being administered in mass‑vaccination campaigns worldwide. Preventive measures include physical distancing, ventilation, mask use, hand hygiene and isolation of cases. Treatment remains largely supportive, focusing on symptom management and experimental therapies.