Influenza Virus Evolution: Challenges of Antigenic Drift and Shift in Vaccine Design and Response
I ntroduction The under lying principles of influenza vaccination have not altered significantly over 70 years. The greatest challenge lies in the virus continuously evolving by antigenic drift and shift, reducing the efficacy of the vaccine and requiring ongoing revision. Curren tly, available vaccines rely on the tactic of attacking specific viral proteins, which are too few to defend against all the strains. Developing effective vaccines for influenza is complicated due to the virus’s propensity to mutate frequently, especially in the hemagglutinin (HA) protein. Even though antibodies to the HA head are known to neutralize infection, this region is highly variable, and therefore, vaccines are not very effective in the long term. Thus, vaccines currently in use offer temporary protection and must be updated annually. Influenza A and B viruses continue to cause severe disease across the globe, and evolutio n is tracked by the WHO for vaccine composition. Although this system en...