Pandemic Influenza

An influenza pandemic is caused by a virus that is either entirely new or has not circulated recently and widely in the human population. This creates an almost universal vulnerability to infection. While not all people will become infected during a pandemic, nearly all people are susceptible to infection.

The occurrence of large numbers of people falling ill at or around the same time is one reason why pandemics are socially and economically disruptive, with a potential to temporarily overburden health services.

There have been four influenza pandemics documented since the early part of the twentieth century, including the H1N1 pandemic that occurred in 2009.

It is not possible to predict accurately when influenza pandemics will occur or how severe they will be. However, the current outbreak of avian influenza in Asia, Europe, and Africa has influenza experts concerned that a pandemic is developing that may be severe.