The FDA recently announced that it had approved this year’s seasonal influenza (flu) vaccines that include the new strains of virus judged likely to cause flu in the Northern Hemisphere in 2006-2007.

“These approvals signal our commitment to doing all we can to help ensure the timely availability of seasonal flu vaccine for the American public,” said Jesse L. Goodman, MD, MPH, director of FDA’s Center for Biologics Evaluation and Research. “We will continue to work closely with the manufacturers so they can deliver vaccine in time for the start of vaccinations, which begin in the fall.”

Each year influenza vaccine manufacturers submit information and samples to FDA of their virus strains being manufactured for the upcoming seasonal influenza season for review and testing in FDA laboratories. Because different influenza virus strains may appear each year, one or more of the strains in the vaccine may need to be changed to protect against what public health experts think are the strains most likely to infect people that year. This season’s approved formulation for the U.S. vaccine is identical to that recommended by both the World Health Organization and FDA’s Advisory Committee. The formulation includes one strain that was used in last year’s vaccine and two new strains. Seasonal flu vaccines do not protect against avian flu, which is caused by different viral strains.

Influenza or “the flu” is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness, and at times can lead to death. The best way to prevent this illness is by getting vaccinated. Although it is best to be immunized in the fall, getting the vaccine in the winter months when flu season often peaks is also recommended.

According to the Centers for Disease Control and Prevention, every year in the United States, on average five to 20 percent of the population gets the flu, more than 200,000 people are hospitalized from its complications and approximately 36,000 people die from it. Some individuals are at high risk for serious complications from influenza, such as the elderly, children, and people with certain chronic medical conditions.

There are four vaccine manufacturers approved to market their vaccines in the United States: Chiron Vaccines, Ltd.; GlaxoSmithKline Biologicals; MedImmune Vaccines, Inc.; and Sanofi Pasteur, Inc. The manufacturers have projected making a total of about 100 million doses of influenza vaccine for the 2006–2007 season, but these projections could change as manufacturing continues.