What an influenza pandemic

An influenza pandemic is an epidemic on a global scale caused by a new strain having the following five characteristics:

– it is able to multiply in the human body;

– It causes serious illness or serious complications or death;

– It is easily transmitted between humans, leading to sustained chains of transmission and outbreaks across entire populations;

– It is new, and the population has no immunity against it;

– Any treatment or quickly accessible and effective vaccination against it does exist.