COVID-19 disease overview and public health guidance

COVID-19 is a contagious illness caused by the SARS‑CoV‑2 virus that began spreading worldwide in January 2020, leading to a global pandemic. Common symptoms include fever, fatigue, cough, difficulty breathing, loss of smell and taste, with about 81 % experiencing mild to moderate illness, 14 % developing severe disease, and 5 % becoming critical.

Transmission occurs through inhalation of infectious particles or contact with contaminated surfaces, and individuals 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 swabs. Vaccines have been approved and are being distributed in many countries, while preventive measures emphasize physical distancing, mask usage, ventilation, hand hygiene, and isolation of cases.

Long‑COVID effects and organ damage have been reported in some survivors, prompting ongoing research into the disease’s lasting impacts.