Influence of social and lifestyle factors on seasonal influenza severity and flu vaccine efficacy

A scoping review will outline current evidence on the effect of socioeconomic status (SES) on influenza and COVID-19 vaccine efficacy and the influence of obesity, dietary and lifestyle factors on vaccine efficacy. Informed by these findings, our first epidemiological study will use UK Biobank data to generate evidence on the relationship between SES and vaccine efficacy and whether body composition, lifestyle factors, dietary intake affect this relationship. Due to limitations in the UK Biobank dataset, a second epidemiological study will use primary care data to explore the effect of SES on influenza/COVID-19 incidence/severity and vaccine efficacy in a cohort more representative of the general population in the United Kingdom. Applying our findings from the scoping review and epidemiological work, a cross-sectional study will recruit participants in Autumn/Winter 2025/26 (to be extended in the next flu season if sample size not reached). This lab-study will investigate if SES affects flu and/or COVID-19 vaccine efficacy one and four months after vaccination. Vaccine efficacy will be measured directly via antibody levels and/or by vaccine/antigen-stimulated immune responses. Finally, based on these collective findings, we aim to co-design a pilot study intervention to improve influenza/COVID-19 vaccine efficacy in people of lower SES/other identified disadvantaged group.