The US Food and Drug Administration's Vaccines and Related Biological Products Advisory Committee (VRBPAC) recently voted to change 1 strain in next season's influenza vaccine, anticipating that it will help the vaccine better match circulating viruses.

The Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) routinely monitor influenza viruses and report on which strains are predominant so that health officials may use those data to select the 3 strains most likely to offer protection for the following season. Each year's influenza vaccine typically contains 2 "A" influenza strains that include an H1N1 subtype and an H3N2 subtype and 1 "B" strain.

For the 2009-2010 influenza vaccine, VRBPAC unanimously recommended to:

• Keep both influenza "A" components the same
• Replace the influenza "B" component with one from the Victoria lineage

The CDC's Advisory Committee on Immunization Practices (ACIP) also supported WHO and VRBPAC's recommendations.

Although VRBPAC typically recommends 2 "A" strains and 1 "B" strain each year, the subtypes often change from year to year, which presents challenges for vaccine manufacturers, as the vaccine components may be new each season. Likewise, manufacturing facilities must be prepared to accommodate timely production of various "A" and "B" type strains within a few short months between the time that VRBPAC and ACIP vote on the strains in February and the start of the flu season the following fall.

For a full transcript of the VRBPAC meeting, please click on the following link: http://www.fda.gov/ohrms/dockets/AC/09/transcripts/2009-4416T1-1.htm.

Please click on the following link to see Wall Street Journal coverage of this meeting: http://online.wsj.com/article/SB123500842581018663.html.