Flu Universal Vaccines: New Tricks on an Old Virus

Conventional influenza vaccines are based on predicting the circulating viruses year by year, conferring limited effectiveness since the antigenicity of vaccine strains does not always match the circulating viruses. This necessitates development of universal influenza vaccines that provide broader and lasting protection against pan-influenza viruses. The discovery of the highly conserved immunogens (epitopes) of influenza viruses provides attractive targets for universal vaccine design. Here we review the current understanding with broadly protective immunogens (epitopes) and discuss several important considerations to achieve the goal of universal influenza vaccines.