The flu, also known as influenza, is a contagious respiratory disease caused by influenza viruses. In the United States, flu season begins every fall and ends every spring. The flu people get duing this season is called seasonal flu. Sometimes, a new type of flu virus comes along to which poeple have no resistance. When this happens, it can spread more easily from person to person around the world in a very short time, causing illness and death. This is a pandemic flu.
Pandemic flu is more serious than seasonal flu. Most people will recover from seasonal flu within a week or two and do not require medical treatment. Pandemic flu is different because more people who get it might not recover, even with medical treatment. There may not be a vaccine for pandemic flu until reasearchers and pharmaceutical companies are able to create one. Vaccine development depends on the scientific understanding of the specific virus causing the disease. Even if a vaccine is found, it will be a challenge to produce enough of it and get it to all the people who need it. Scientists cannot accurately predict whether the bird flu virus will cause the next human pandemic or when the next pandemic will occur.
In the 20th century, flu pandemics occurred in 1918, 1957, and 1968. The 1918 pandemic led to high levels of illness, death and social disruption and economic loss. It is estimated it killed more that 20 million people worldwide.
