Seasonal influenza vaccine uptake among patients with cardiovascular disease in Denmark, 2017–2019

BACKGROUND: Influenza vaccination protects against morbidity and mortality in patients with cardiovascular disease (CVD). We aimed to describe influenza vaccine uptake in patients with CVD in a universal-access healthcare system. METHODS: Using nationwide Danish registries, we included all patients with prevalent CVD, defined as heart failure (HF), atrial fibrillation (AF), ischemic heart disease (IHD), or stroke during three consecutive influenza seasons (October–December 2017–2019). The outcome was relative frequency of influenza vaccination across strata of patient characteristics. RESULTS: There was an average of 397 346 patients with CVD yearly during 2017–2019. Vaccine uptake was 45.6% for the whole population and ranged from 55.0% in AF to 61.8% in HF among patients aged ≥65 years. Among patients aged <65 years, uptake was 32.6% in HF, 19.0% in AF, 21.1% in IHD, and 18.3% in stroke. There was a lower uptake with decreasing age: 21.6% in HF, 5.5% in AF, 7.4% in IHD, and 6.3% in stroke among males aged <45 years, as opposed to 25.5% in HF, 11.5% in AF, 13.8% in IHD, and 12.1% in stroke for males aged 45–54 years. In the further stratified analyses, uptake ranged from a low of 2.5% for males <45 years with AF who were not vaccinated the previous season to a high of 87.0% for females ≥75 years with IHD who were vaccinated the previous season. CONCLUSION: Seasonal influenza vaccine uptake is suboptimal among patients with CVD, even in a universal-access healthcare system with free-of-charge vaccinations. Vaccine uptake was particularly low among young patients.