Introduction
Influenza infection is a major precipitating factor for worsening heart failure (HF), especially during annual flu seasons. Despite recognition of this risk, uptake of influenza vaccination among HF patients remains globally low, particularly in Asia where rates are reported below 3%, with China having even less than 1%. Previously, lack of robust randomized clinical trial data limited the strength of guideline recommendations, which often classified flu vaccination as a modest IIa-level advisory rather than mandatory management. The critical clinical question remained: does influenza vaccination concretely improve prognosis and survival in patients with acute heart failure?
