Who discovered the influenza vaccine?

Why has there not been a quadravalent influenza vaccine approved until recently?

• GSK's Fluarix quadravelent flu vaccine has been recently been approved, should be available next flu season. Why has there not been a quadravalent A/A/B/B vaccine previously available? Are there technical or FDA approval reasons? Or was there just not believed enough diversity in type B strains to justify this?

• Answer:

  Flu B tends to be a poor relation to FluA. It tends to 'only' cause seasonal flu and doesn't undergo the reassortment events FluA does that allows the latter to cause Pandemics (it's easier to get FluA research funding 'cause you can point to the 1918 devastating pandemic). Also FluA has multiple subtypes so a H1N1 & H3N2 are usually selected. There are two lineages of flu B, they split off sometime in the late 80s (ish). Creatively named Yamagata-like & Victoria-like. Dogma had it that only one would dominantly circulate each flu season so you could take an educated guess which it would be by looking what was circulating on the other hemisphere during their flu season. But one year the guess was wrong and we are beginning to see more co-circulation of the two lineages too. Oh and the clinical/decision makers are becoming more aware that actually 'mild' flu B can also cause a severe illness. (I work on flu B whenever funding allows, so I may be a bit biased).