Tiny tweaks helped flu strains thwart 2014-2015 vaccine

Changes to the flu strains circulating around the Northern Hemisphere explain why last year’s flu vaccine didn’t work so well.
Judy Schmidt/CDC(CC0 1.0)
Changes to the flu strains circulating around the Northern Hemisphere explain why last year’s flu vaccine didn’t work so well.
Judy Schmidt/CDC(CC0 1.0)