Update on the Efficacy of Vaccination on Host Immunity to Influenza Virus Infection.

backgroundInfluenza is a highly contagious viral disease that infects the epithelial cells of the upper and lower respiratory tract. Among circulating viruses, influenza A and B strains are responsible for the majority of clinically significant disease and seasonal epidemics. SUMMARY: The severity of influenza infection and the effectiveness of vaccination are largely determined by the magnitude and quality of the host immune response. Both innate and adaptive immune mechanisms contribute to viral clearance, recovery, and the establishment of protective immunity. Although vaccination remains the most effective strategy to reduce influenza-related disease burden, its efficacy varies due to viral evolution, host factors, and immune response variability. KEY MESSAGES: Ongoing surveillance of circulating influenza strains and continued advancements in vaccine design are essential for improving preventive strategies and protecting public health. Further research into novel vaccine approaches and immune mechanisms is critical to enhance vaccine efficacy, address vaccine hesitancy, and ultimately reduce influenza-associated morbidity and mortality.