
Influenza, or the flu, is a disease that rapidly produces symptoms such as body aches, headache, fever, chills, sore throat, runny nose, and nonproductive cough. Influenza is highly contagious and is easily passed from person to person, primarily through small droplets produced from a cough or sneeze of an infected individual.
A pandemic refers to a worldwide outbreak of influenza when a new strain of a virus emerges. In early stages of the pandemic, people may have little or no natural immunity to the virus; so the disease may spread quickly. Vaccines to protect people from the illness may not be widely available until months after the pandemic begins. Pandemics have occurred throughout history with one of the worst occuring in 1918.
On June 11, 2009, the World Health Organization raised the pandemic alert to for the Influenza A (H1N1) virus to Phase 6, the highest level, in response its ongoing global spread. This means that a pandemic is underway. The decision to raise the pandemic alert to Phase 6 is a reflection of the spread of the virus, not its severity.