Duration of the Humoral Immune Response to Influenza Vaccination in a Cohort of Repeatedly Vaccinated Adults over Four Consecutive Epidemic Seasons: 2018/19–2021/22 Observational Study
Background/Objectives: The impact of repeated annual influenza vaccination on long-term immunogenicity and protection remains debated. Although reduced fold-increases in antibody titers are often observed in repeatedly vaccinated individuals, the effect on the duration of the humoral response remains poorly understood....