VAccination to Improve Clinical outComes in Heart Failure Trial (VACC-HeFT): a Feasibility Study

This is a randomized, double blind, active-control trial of high dose influenza vaccine compared to standard dose influenza vaccine for one season in adult participants with symptomatic heart failure(HF). The primary outcome measure is humoral (antibody-mediated) immune response, and secondary outcomes include cumulative incidence of influenza-like illness symptoms and all cause hospitalizations. The aim is to gather information on feasibility of this study design and effect size differences to inform a larger outcomes-based clinical trial.

The 5.8 million Individuals in the US with heart HF are at high risk for influenza infection and associated morbidity, mortality and increased health care costs despite annual influenza vaccination. Higher dose of vaccine is approved for use in older adults. Antibody-mediated immunity contributes to vaccine-induced protection from influenza illness. Investigators at University of Wisconsin(UW) Madison have demonstrated reduced antibody titers to influenza vaccination in patients with HF. Additionally, study team has shown in a pilot study that double dose influenza vaccine resulted in increased titers and was well tolerated.

A multi-center, prospective, randomized, open-label blinded-endpoint trial will be conducted with 20 participants assigned to the standard dose vaccine dose and 20 participants to high dose influenza vaccine. The primary outcome measure is the rate of seroconversion (4-fold rise in antibody titers to A/H3N2, A/H1N1, and B-type vaccine antigens), assessed 4 weeks post vaccination. The study will also examine feasibility differences in symptoms of influenza and all-cause hospitalizations between vaccine dose groups, and these data will be used for planning a subsequent outcomes-based clinical trial.