The association between severity and aetiology of chronic liver disease and seasonal influenza vaccination uptake in adults: a retrospective cohort study using English primary care data (2019-2024)

BackgroundIn England, individuals with chronic liver disease (CLD) are among those with the lowest seasonal influenza vaccine uptake despite being at elevated risk of severe influenza. We examined the relationship between CLD severity and aetiology, and influenza vaccine uptake in England. MethodsA retrospective cohort study of adults (18-115 years) using Clinical Practice Research Datalink Aurum primary care data was conducted for five seasons (2019/20-2023/24). Poisson regression was used to estimate rates of uptake by CLD severity (clinical diagnoses categorised as low, moderate, or severe) and aetiology (alcohol-related, viral-related, and diagnoses in the Green Book guidelines). FindingsThere were 182,174-277,470 with CLD per cohort. Among those who were additionally age-eligible for vaccination, uptake was 71{middle dot}1-79{middle dot}7% compared to 30{middle dot}9-40{middle dot}5% in those not additionally age-eligible. Among individuals below age eligibility without other comorbidities, severity was associated with higher uptake (incidence rate ratio [IRR] moderate 1{middle dot}80, 95% CI 1{middle dot}69-1{middle dot}90; severe 1{middle dot}95, 95% CI 1{middle dot}84-2{middle dot}08 in 2023/24); there was no effect in those with at least one additional comorbidity (moderate 1{middle dot}05, 95% CI 0{middle dot}99-1{middle dot}10; severe 1{middle dot}05, 95% CI 1{middle dot}01-1{middle dot}09). Alcohol- and viral-related aetiology were also associated with increased uptake in those not additionally age-eligible. Among individuals meeting age eligibility without additional comorbidities, severity was associated with a reduced uptake (moderate 0{middle dot}81, 95% CI 0{middle dot}73-0{middle dot}90; severe 0{middle dot}79, 95% CI 0{middle dot}74-0{middle dot}85), with attenuation in those with additional comorbidities (moderate 0{middle dot}99, 95% CI 0{middle dot}94-1{middle dot}04; severe 0{middle dot}91, 95% CI 0{middle dot}89-0{middle dot}94). InterpretationCLD severity and aetiology were important determinants of uptake in the absence of additional indications for influenza vaccination. Future research should prioritise understanding facilitators and barriers to vaccine uptake in individuals with CLD, particularly for those at highest risk of severe infection. FundingNIHR Health Protection Research Unit in Vaccines and Immunisation (NIHR200929/NIHR207408). Research in contextO_ST_ABSEvidence before this studyC_ST_ABSWe searched PubMed up to June 2025 using the terms "chronic liver disease", "cirrhosis", "hepatitis", "influenza vaccination", "seasonal influenza", and "vaccine uptake". Previous research, including national data from England, has shown that people with chronic liver disease tend to have lower seasonal influenza vaccine uptake than individuals with other medical comorbidities which qualify for vaccination such as diabetes, chronic kidney disease or immunosuppression. The reasons for low influenza vaccine uptake in people with chronic liver disease are not well understood, and it is therefore difficult for vaccination providers, principally primary care services in England, to tailor interventions aimed to increase uptake. Qualitative research involving individuals aged less than 65 years living in England with clinical risk comorbidities, most commonly diabetes, found that chronic disease management pathways inconsistently provided information about the importance of influenza vaccination as part of chronic disease management. Individuals with long-term conditions reported low perceived risk of influenza infection and limited awareness of vaccine benefits as important reasons for non-uptake. We hypothesised that the severity and aetiology of chronic liver disease may be important determinants of uptake. Added value of this studyWe conducted a population-based study to examine how chronic liver disease severity and aetiology influence seasonal influenza vaccine uptake in adults in England. Using primary care electronic health record data from five consecutive influenza seasons (2019/20-2023/24), we found that more severe chronic liver disease was associated with a substantial increase in vaccine uptake in those without additional indications for seasonal influenza vaccination (age-based eligibility or other qualifying clinical risk comorbidities). Alcohol- and viral-related aetiology were also associated with increased uptake in those who were not additionally age-eligible for vaccination. In contrast, severity, alcohol- and viral-related underlying aetiology were associated with a modest reduction in uptake for individuals with chronic liver disease who also qualified for vaccination due to age. Implications of all the available evidenceDespite clear clinical vulnerability to infection and a substantially elevated risk of morbidity and mortality following infection, a large proportion of adults with chronic liver disease, particularly those aged under 65 years, remain unvaccinated against seasonal influenza each year. This study suggests that chronic liver disease severity and underlying aetiology are important determinants of uptake in individuals not meeting age-based vaccine eligibility, particularly in those without additional clinical risk comorbidities. This could be because of differing perceptions of influenza risk, or due to varying degrees of interaction with healthcare specialists as part of chronic disease management. In individuals who met age-based vaccination eligibility, the negative effect of severity on influenza vaccine uptake may reflect greater barriers to accessing vaccination services by those with more complex health needs, or competing medical priorities for long-term condition management during consultations. To inform targeted vaccination strategies, future research should aim to understand the specific facilitators and barriers to influenza vaccination experienced by individuals with chronic liver disease. This should include perspectives of individuals with different disease severity, across different age groups, in those with and without additional co-morbidities.