What is Pandemic Flu?

New strains of influenza circulate in a community every year; these strains acquire small mutations which make them different from previous flu strains. 

Since the new viruses are different than ones we've encountered before, they can still make us sick.  However, the modifications of the virus are usually minor, so some people still have immune protection against the virus. 

The fact that many people have some level of immunity means that we usually do not observe seasonal flu causing a "pandemic," or global outbreak. 

Flu shots (vaccines) are made each year for seasonal flu.

This can arise when there is an exceptionally different strain of influenza to which people have no previous immune protection.

Pandemic flu strains are very virulent, meaning that they cause disease among people who may otherwise not get sick. Because people have little immunity to the virus, the disease can spread easily throughout communities and result in a global outbreak. 

There is no flu shot (vaccine) available for pandemic flu.