The US Food and Drug Administration has announced this year’s seasonal influenza vaccines that include new strains of the virus likely to cause flu in the United States during the 2008-2009 season.
The six vaccines and their manufacturers are: CSL Limited, Afluria; GlaxoSmithKline Biologicals, Fluarix; ID Biomedical Corporation of Quebec, FluLaval; MedImmune Vaccines Inc, FluMist; Novartis Vaccines and Diagnostics Limited, Fluvirin; and Sanofi Pasteur Inc, Fluzone.
Approval information and specific indications can be found on the FDA’s Web site. This season’s vaccines contain three strains of the influenza virus that disease experts expect to be the most likely cause of the flu in the United States.
Each season’s vaccines are modified to reflect the virus strains most likely to be circulating. The closer the match between the circulating strains and the strains in the vaccines, the better the protection.
There is always a possibility of a less than optimal match between the virus strains predicted to circulate and what virus strains end up causing the most illness. Even if the vaccines and the circulating strains are not an exact match, they will provide some protection and may reduce the severity of the illness or prevent flu-related complications.
The FDA changed all three strains for this year’s influenza vaccine—an unusual occurrence, as usually only one or two strains are updated from year to year. Influenza is unique in that it requires a new vaccine to be created every year. A list of the strains included in the 2008-2009 vaccine is also available from the FDA’s 2008-2009 flu season Web site. Two of the three strains recommended for the US this year are now in use for the Southern Hemisphere’s 2008 influenza season, which is currently underway.
Each year, experts from the FDA, World Health Organization, US Centers for Disease Control and Prevention (CDC), and other institutions study virus samples and patterns collected throughout the year from around the world in an effort to identify strains that may cause the most illness in the upcoming season.
Based on those forecasts and on the recommendations of its Advisory Committee, the FDA each February decides on the three strains that manufacturers should include in their vaccines for the US population. The FDA makes this decision early in the year so that manufacturers have enough time to produce the new vaccines.
Vaccination remains the cornerstone of preventing influenza, a contagious respiratory illness caused by influenza viruses. According to the CDC, every year an average of 5 to 20 percent of the US population gets the flu, more than 200,000 are hospitalized from flu complications and there are about 36,000 flu-related deaths. Some individuals—the elderly, young children, and people with chronic medical conditions —are at higher risk for flu-related complications. Vaccination of these groups and of health care personnel is critical, and can have a strong impact in the annual battle against influenza.