Influenza viruses are responsible for millions of cases globally and significantly threaten public health. Since pandemic and zoonotic influenza viruses have emerged in the last 20 years and some of the viruses have resulted in high mortality in humans, a universal influenza vaccine is needed to provide comprehensive protection against a wide range of influenza viruses. Current seasonal influenza vaccines provide strain-specific protection and are less effective against mismatched strains. The rapid antigenic drift and shift in influenza viruses resulted in time-consuming surveillance and uncertainty in the vaccine protection efficacy. Most recent universal influenza vaccine studies target the conserved antigen domains of the viral surface glycoproteins and internal proteins to provide broader protection. Following the development of advanced vaccine technologies, several innovative strategies and vaccine platforms are being explored to generate robust cross-protective immunity. This review provides the latest progress in the development of universal influenza vaccines.
Keywords: broadly protective influenza vaccine; conserved influenza antigens; influenza vaccine; pandemic influenza vaccine; pandemic preparedness; universal influenza vaccine.