Influenza Flu

About Influenza Flu

Influenza is a contagious respiratory illness caused by influenza A and B viruses. The disease is characterized by sudden onset of fever, chills, muscle aches, headache, fatigue, dry cough, and sore throat. Unlike the common cold, flu onset is abrupt and symptoms are more severe. Seasonal flu epidemics occur annually worldwide, causing an estimated 3 to 5 million severe cases and 290,000 to 650,000 respiratory deaths each year according to WHO. The virus spreads through respiratory droplets and contaminated surfaces. Antigenic drift causes seasonal variation, requiring annual vaccine updates. Antigenic shift can produce pandemic strains. The flu vaccine is the primary prevention tool, with effectiveness that varies from season to season depending on how well it matches circulating strains. Antivirals including oseltamivir Tamiflu, zanamivir Relenza, and baloxavir Xofluza may be prescribed by clinicians, particularly for people at higher risk, and work best when started early in the illness. Flu is most dangerous for the elderly, young children, pregnant women, and those with chronic conditions.