Data and statistics

Influenza is an acute viral infection that primarily attacks the upper respiratory tract, including the nose, throat, bronchi and, less frequently, the lungs. The disease occurs worldwide and spreads very quickly in populations, especially in crowded circumstances. In the northern hemisphere, annual influenza epidemics occur during autumn and winter affecting approximately 5-15% of the population.


Influenza is characterized by a sudden onset of high fever, cough, headache, muscle and joint pain, malaise, and a runny nose lasting 2 to 7 days. Influenza is usually mild and uncomplicated and most people recover without medical treatment. However infection with influenza may occasionally cause severe disease and death, particularly among the elderly, pregnant women, very young children and persons with certain medical conditions (including chronic heart, lung, kidney, liver, blood or metabolic diseases, or weakened immune systems).


The most effective way to prevent the disease or severe outcomes from the illness is through vaccination. For more information on vaccination follow the link to the left.

Influenza viruses mainly spread from person to person through respiratory droplets produced when an infected person coughs or sneezes, or through contaminated hands and surfaces. To reduce transmission, people with symptoms of respiratory infection should therefore keep their distance from others and practice good respiratory hygiene to prevent droplet transmission: people should cover their mouth and nose with a tissue when coughing or sneezing, and wash their hands regularly.