The flu jab you get (or at least, should get) each winter contains the deactivated (dead) remnants of the flu viruses that the World Health Organization predicts will be prevalent that year. Your body uses this to “understand” what kind of virus it should be expecting to see down the road, and prepares its defenses accordingly.
This vaccine normally means you can protect yourself from three or four strains of influenza. What this new vaccine essentially does is give the body the genetic blueprints that most influenza strains share. Even if the strains evolve that year into something else, they’ll still have the same ancestral genes – and consequently, your immune system will still be able to exploit this weakness and destroy them.
It’s too soon to say whether this vaccine will work on people, but it’s promising. As many as 56,000 people in the US die from influenza every single year. A near-universal flu shot could make this a thing of the past.