Flu Seasons

2004–2005 flu season

The 2004–05 trivalent influenza vaccine for the United States contained A/New Caledonia/20/99-like (H1N1), A/Fujian/411/2002-like (H3N2), and B/Shanghai/361/2002-like viruses.

2005–2006 flu season

The vaccines produced for the 2005–2006 season use:

• an A/New Caledonia/20/1999-like(H1N1);
• an A/California/7/2004-like(H3N2) (or the antigenically equivalent strain A/New York/55/2004);
• a B/Jiangsu/10/2003-like viruses.

2006–2007 flu season

The 2006–2007 influenza vaccine composition recommended by the World Health Organization on 15 February 2006 and the U.S. FDA's Vaccines and Related Biological Products Advisory Committee (VRBPAC) on 17 February 2006 use:

• an A/New Caledonia/20/99 (H1N1)-like virus;
• an A/Wisconsin/67/2005 (H3N2)-like virus (A/Wisconsin/67/2005 and A/Hiroshima/52/2005 strains);
• a B/Malaysia/2506/2004-like virus from B/Malaysia/2506/2004 and B/Ohio/1/2005 strains which are of B/Victoria/2/87 lineage.

2007–2008 flu season

The composition of influenza virus vaccines for use in the 2007–2008 Northern Hemisphere influenza season recommended by the World Health Organization on 14 February 2007 was:

• an A/Solomon Islands/3/2006 (H1N1)-like virus;
• an A/Wisconsin/67/2005 (H3N2)-like virus (A/Wisconsin/67/2005 (H3N2) and A/Hiroshima/52/2005 were used at the time);
• a B/Malaysia/2506/2004-like virus

"A/H3N2 has become the predominant flu subtype in the United States, and the record over the past 25 years shows that seasons dominated by H3N2 tend to be worse than those dominated by type A/H1N1 or type B." Many H3N2 viruses making people ill in this 2007–2008 flu season differ from the strains in the vaccine and may not be well covered by the vaccine strains. "The CDC has analyzed 250 viruses this season to determine how well they match up with the vaccine, the report says. Of 65 H3N2 isolates, 53 (81%) were characterized as A/Brisbane/10/2007-like, a variant that has evolved [notably] from the H3N2 strain in the vaccine—A/Wisconsin/67/2005."