Every year, between 4 and 20 percent of the world population catches some form of influenza. Influenza, or the flu, is an infection caused by a viruses, much like the common cold, but unlike the common cold, the flu, whether seasonal, avian, or swine, has killed millions around the world throughout recorded history. Advances in science are producing effective vaccines and medications to combat this disease, but the influenza virus continues to change...