New B strain slated for flu vaccine

The influenza vaccine to be given in the 2002-2003 flu season should be changed to include a component against the B/Hongkong/330/2001-like virus, the Food and Drug Administration’s Vaccines and Related Biological Products Advisory Committee has recommended.

The vaccine for the 2001-2002 seasons included the B/Sichuan/379/99-like virus. Unchanged are the vaccines’ two components against A-type influenza: the A/New Caledonia/20/99(HINI)-like and an A/Moscow/10/99(H3N2)-like virus, probably the A/Panama/ 2007/99 strain. The 2001-2002 influenza seasons have been moderately active, with no excess deaths due to pneumonia and influenza as of early March. The B strains of influenza, chief of the influenza branch at the Centers for Disease Control and Prevention, Atlanta, told the committee.

The low level of activity of any B strains makes it more likely that there will be excess cases of influenza B in 2002-2003. The committee considered CDC surveillance data that showed a shift in which B strain has caused the most cases of influenza this season. Data from Canada show that 94 percent of B-strain infections have been due to the Hongkong 93 percent of B-strain infections specifically the B/Victoria strain. So far the United States has had only a few cases caused by a B/Hongkong-like virus. There has not been a significant outbreak of influenza B caused by B/Victoria for 10 years; as a result, most children under 12 would be susceptible.

The ideal influenza vaccine would be a quadrivalent vaccine that would make it unnecessary to predict the future in order to choose the right B strain. However, the FDA, Bethesda, reminded them that there is little research into the safety and efficacy of a quadrivalent influenza vaccine.