Sequential Digital Intervention to Increase Influenza Vaccination in Patients With Heart Failure

Influenza vaccination is an important preventive measure for patients with heart failure (HF), but vaccination uptake remains low in China. Although previous studies have demonstrated the benefits of actively promoting influenza vaccination, scalable strategies to improve vaccination uptake among patients with HF after hospital discharge remain insufficiently evaluated. The PANDA-BOOST trial is a prospective, pragmatic, open-label, two-stage sequential randomized clinical trial involving participants previously enrolled in the PANDA II trial. The study aims to evaluate whether sequential digital interventions using artificial intelligence (AI)-assisted telephone calls and short message service (SMS) reminders improve influenza vaccination uptake compared with a single routine vaccination recommendation. After an initial AI-assisted telephone call providing a standardized influenza vaccination recommendation, eligible unvaccinated participants will be randomized in a 1:2 ratio to a routine recommendation group or a sequential digital intervention group. Participants in the sequential intervention group will receive additional AI-assisted telephone calls approximately 14 and 28 days after the initial call. Those who remain unvaccinated and meet eligibility criteria at the third call will undergo a second randomization in a 1:1:1 ratio to no additional SMS, gain-framed SMS, or loss-framed SMS. The primary outcome is influenza vaccination uptake within two months after the first-stage randomization.