Laserfiche WebLink
60 <br /> <br />I. INTRODUCTION: <br />Pandemics are distinct from seasonal influenza epidemics that happen nearly every year. <br />Seasonal influenza epidemics are caused by influenza viruses that circulate around the world. <br />Over time, people develop some degree of immunity to these viruses and vaccines are developed <br />annually to protect people from serious illness. Pandemic influenza refers to a worldwide <br />epidemic due to a new, dramatically different strain of influenza virus. A pandemic virus strain <br />can spread rapidly from person to person and, if severe, can cause high levels of disease and <br />death around the world. <br />Pandemic viruses develop in two main ways. First, wild birds are the reservoir for all influenza <br />viruses. Most avian influenza viruses do not infect or cause significant disease in humans. <br />However, new pandemic influenza viruses can arise when avian influenza viruses acquire the <br />ability to infect and cause disease in humans and then spread rapidly from person to person. <br />Secondly, all influenza viruses experience frequent, slight changes to their genetic structure over <br />time. <br />The development of a novel virus means that most, if not all, people in the world will have never <br />been exposed to the new strain and have no immunity to the disease. It also means that new <br />vaccines must be created and are not likely to be available for months. <br />Flu pandemics have occurred throughout history. The influenza pandemic of 1918 caused more <br />than 500,000 deaths in the United States and more than 40 million deaths around the world. <br />Subsequent pandemics in 1957-58 and 1968-69 caused far fewer fatalities in the US, but caused <br />significant morbidity and mortality around the world. In 2009, the first US case of H1N1 (swine <br />flu) was diagnosed. The CDC estimates that 43 million to 89 million people had H1N1 between <br />2009 and 2010 with 8,870 and 18,300 H1N1 related deaths. <br />