FDA panel approved four-strain flu shot Share This: UPI 3/1/2013 3:37:23 AM WASHINGTON, Feb. 28 (UPI) -- An advisory committee on vaccines for the U.S. Food and Drug Administration approved adding a fourth strain of influenza to next year's seasonal flu vaccine. The advisory panel signed off on the quadrivalent vaccines, which will contain two "A" strains and two "B" strains and the panel also recommended that the "B" strain used in this year's vaccine be changed to offer a better match against B strains causing some influenza illnesses, The Wall Street Journal reported. Boosting the seasonal flu vaccine has been in the work for years and after the recommendation, GlaxoSmithKline and MedImmune, a unit of AstraZeneca, said they planned to offer quadrivalent vaccines for the 2013-14 influenza season. MedImmune, which makes a vaccine in the form of a mist administered through the nose, said it would completely switch to a four-strain vaccine, while GlaxoSmithKline said it would offer both types of vaccines, the newspaper reported. Sanofi officials said it has an application pending with the U.S. Food and Drug Administration for a four-strain vaccine, but cannot accept orders until after it is approved -- meaning the firm would mostly sell its usual three-strain or trivalent vaccine later this year. Dr. Leonard Friedland, the head of GSK North America Vaccines Clinical Development and Medical Affairs, said some flu illnesses this year were caused by a B strain not included in this year's vaccine and the B strain tends to hit after most have been exposed to the A strain. This year the dominant H3N2, "A" virus caused most illnesses. However, while the four-strain vaccines should offer better protection against the influenza, it wouldn't help the larger problem that this year's flu vaccine was only effective with 9 percent of those vaccinated age 65 and older.