Twice a year influenza experts meet at the World Health Organization to pore over surveillance data provided by countries around the world to try to predict which strains are becoming the most dominant. The Northern Hemisphere strain selection meeting is held in late February; the Southern Hemisphere meeting occurs in late September.
The selections that officials made [recently] for the next Southern Hemisphere vaccine suggest that two of four viruses in the Northern Hemisphere vaccine that doctors and pharmacies are now pressing people to get may not be optimally protective this winter. Those two are influenza A/H3N2 and the influenza B/Victoria virus.
The strain selection committee concluded the H3N2 and B/Victoria viruses needed to be updated because the ones used in the Northern Hemisphere vaccine didn’t match the strains of those viruses that are now dominant. Influenza epidemiologist Dr. Danuta Skowronski described the significance of those two changes in one word: “mismatch.”
The sliver of good news: The officials meeting at the WHO last week concluded that the H1N1 and the flu B/Yamagata components of the Southern Hemisphere vaccine didn’t need to change.
Read full, original post: Flu vaccine selections may be an ominous sign for this winter