Infections caused by influenza viruses occur regularly throughout the world - either as frequent, but unpredictable epidemics, or as pandemics - and can affect all people, regardless of their age, sex, and race.
Annually, 15,000 to 30,000 hospitalizations (1-2/1,000 inhabitants) and 2,000-2,200 deaths (1,3-1,5/10,000 inhabitants) are related to influenza in the Netherlands . During the epidemic of 1989/90 there were 25,000 deaths in England and Wales attributed to influenza. In addition, influenza also had a severe impact on other diseases, e.g. there was a 25% increase in acute bronchitis and otitis media. In the US, approximately 110,000 hospitalizations and 20,000 deaths per year are due to influenza. According to the Centers for Disease Control(CDC), an influenza pandemic could affect up to 200 million people and result in 400,000 deaths in the US alone.