The FDA has approved the influenza vaccine formulation for the 2011-2012 flu shot. Six manufacturers are licensed to produce and distribute influenza vaccine for the United States.

The vaccine formulation protects patients from the three virus strains most likely to cause the illness in the upcoming flu season. strains used for the 2010-2011 influenza season.

Experts from the CDC, FDA, World Health Organization, and others in the public health community have studied virus samples and patterns collected worldwide to identify virus strains that they predict will be the most common during the upcoming season.

“Vaccines to prevent seasonal influenza have a long and successful track record of safety and effectiveness in the United States,” said Karen Midthun, M.D., director of FDA’s Center for Biologics Evaluation and Research. “It is important to get vaccinated every year, even if the strains in the vaccine do not change, because the protection received the previous year will diminish over time and may be too low to provide protection into the next year.”

Influenza related deaths vary from year to year, but range from as low as 3,000 to a high of 49,000 people in a given flu season. Approximately 5 percent to 20 percent of the U.S. population develops influenza each year, the disease can lead to about 200,000 hospitalizations from related complications, according to the U.S. Centers for Disease Control and Prevention (CDC).