Immunogenicity as a Predictor of Influenza Vaccine Efficacy: A Systematic Review

Influenza represents a significant burden on global public health, and vaccination is the most effective strategy to reduce it. The large investment in vaccination programs and the need for adjustments in vaccine serotypes are important reasons for evaluating the influenza vaccine's efficacy every year. Establishing a relationship between immunogenicity data and efficacy is also crucial for predicting the efficacy of a vaccine during its development. Antibody response measurement is one of the most common methods for evaluating immunogenicity, particularly in vaccines and biologics. The aim of this systematic review was to define a model that relates the immunogenicity of a given vaccine to its efficacy, based on hemagglutination inhibition titer levels.

To achieve this goal, information was gathered from articles linking immunogenicity with the efficacy of the influenza vaccine in the Medline and Scopus databases. Different mathematical models were developed and applied to assess the relationship between HAI titers and the effectiveness of the flu vaccine. This analysis was conducted for the various existing vaccines, for the different influenza virus strains, and for their efficacy in paediatric populations.

The r² obtained ranged from 0.2579 to 0.966, which points to the importance of this immunological factor in the efficacy of the influenza vaccine.

The efficacy values for titer level 40 confirm the validity of the data provided by Hobson.