Effect of seasonal influenza and COVID‐19 vaccination on severity and long‐term outcomes of patients with heart failure decompensations

Abstract Aims To investigate whether seasonal influenza and COVID‐19 vaccinations influence the severity of decompensations and long‐term outcomes of patients with acute heart failure (AHF). Methods and results We included consecutive AHF patients attended at 40 Spanish emergency departments during November and December 2022. They were grouped according to whether they had received seasonal influenza and COVID‐19 vaccination. The severity of heart failure (HF) decompensation was assessed with the MEESSI scale, need for hospitalization, intensive care unit (ICU) admission, and in‐hospital mortality. Long‐term outcomes were 90‐day and 1‐year all‐cause mortality. Associations between vaccination, HF decompensation severity, and long‐term outcomes were investigated. Subgroup analyses were executed for 16 patient characteristics and their relationship with vaccination and 1‐year mortality. We analysed 4243 patients (median age 85 years; interquartile range 77–90; 57% female): 1841 (43%) had received influenza vaccination, 3139 (74%) COVID‐19 vaccination, 1773 (41.8%) received both vaccines (full vaccination) and 1036 (24.4%) none. Previous episodes of AHF, chronic obstructive pulmonary disease and chronic treatment with diuretics were associated with vaccination (either influenza, COVID‐19 and full vaccination). High or very‐high risk decompensation occurred in 18.6%; hospitalization in 72.3%, ICU admission in 1.1%, and in‐hospital mortality in 8.4%. Influenza vaccination was associated with lower hospitalization rates (adjusted odds ratio [OR] 0.746, 95% confidence interval [CI] 0.636–0.876) and in‐hospital mortality (OR 0.761, 95% CI 0.583–0.992), while COVID‐19 vaccination was associated with increased hospitalizations (OR 1.215, 95% CI 1.016–1.454). Overall, 90‐day and 1‐year mortality were 20.3% and 34.4%. Both were decreased in influenza‐vaccinated patients (adjusted hazard ratio [HR] 0.831, 95% CI 0.709–0.973; and HR 0.885, 95% CI 0.785–0.999, respectively) but only at 90 days in COVID‐19 vaccinated patients (HR 0.829, 95% CI 0.702–0.980). Full vaccination achieved even greater reductions in in‐hospital, 90‐day, and 1‐year mortality (HR 0.638, 95% CI 0.479–0.851; HR 0.702, 95% CI 0.592–0.833; and HR 0.815, 95% CI 0.713–0.931, respectively). Subgroup analysis based on patient‐related characteristics demonstrated the consistence of vaccination with long‐term survival. Conclusion In HF patients, seasonal influenza vaccination appears to be associated with less severe decompensation and lower 1‐year mortality, while no firm conclusions can be drawn from the results of the present study regarding the benefits of COVID‐19 vaccination. Full vaccination is associated with the greatest reduction in short‐ and long‐term mortality.