Influenza is a major global public health concern and a huge economic burden to societies. Seasonal influenza epidemics afflict between 13 to 100 million individuals annually, including three to five million cases of severe illness and 300,000 to 600,000 deaths worldwide. This represents a top global public health concern and an extraordinary economic burden to all societies. Pandemics are less frequent, but are generally more severe and pose a greater threat. Over the past century, there have been at least four devastating pandemics caused by the Influenza A virus which took the lives of hundreds of millions of individuals.