by Aimee Keenan-Greene

The U.S. Food and Drug Administration just approved the influenza vaccine formulation for the new 2011-2012 season.

Six manufacturers are licensed to produce and distribute influenza vaccine in the US.

Between 5 - 20 percent of  people develop influenza each year.

That leads to more than 200,000 hospitalizations from related complications, according to the U.S. Centers for Disease Control and Prevention.

Flu season occurs from November to April, with most cases occurring between late December and early March. 

Flu symptoms are usually more severe than the typical sneezing and stuffiness of a cold and include fever, chills, headache, muscle aches, nausea, and diarrhea.  

Symptoms usually resolve in about 1 week for adults, but can last up to 2 weeks for young kids.  

The flu can lead to pneumonia and other life-threatening complications, particularly in infants, senior citizens, and people with long-term health problems.  Influenza-related deaths range from about 3,000 to a high of 49,000 people annually.

The FDA says vaccination remains the cornerstone of preventing the contagious respiratory disease. 

The new  vaccine formulation protects against the three virus strains that surveillance indicates will be most common during the upcoming season. It includes the same virus strains used for the 2010-2011 influenza season.