CLINICAL QUESTION: Does influenza vaccination prior to hospital discharge improve a cause mortality and rates of readmission for patients admitted with acute heart failure (HF)?
BACKGROUND: Influenza vaccination is widely recommended for patients at risk of adverse outcomes, though data for specific at-risk groups are limited. Patients with advanced heart failure are at high risk for mortality and hospital readmission, and interventions to prevent these outcomes are needed.
STUDY DESIGN: Cluster-randomized controlled trial
SETTING: Hospitals from geographically dispersed regions across China were recruited based on their capability to manage high volumes of patients with HF across three influenza seasons from September 2021 through May 2024.
SYNOPSIS: A total of 252 hospitals were identified for eligibility, of which 164 ultimately participated. Across three flu seasons, a total of 7,771 patients with New York Heart Association Class III or IV HF were recruited and randomized between the vaccination and usual care groups. Patients in the vaccination group were offered free influenza vaccination within 24 hours of their planned discharge from the hospital. For the primary analysis, 41.2% of patients in the vaccination group versus 47.0% of patients in the usual care group experienced the composite endpoint of all-cause mortality or any hospital readmission over 12 months (odds ratio [OR], 0.83; 95% confidence interval [CI], 0.72 to 0.97; P=0.019). Results were also statistically significant for the secondary endpoints of all-cause mortality within 12 months, which occurred in 10.0% of the vaccination group and 12.8% in the usual care group (OR, 0.76; 95% CI, 0.69 to 0.84; P <0.0001), and any hospital readmission, which occurred in 35.4% of patients in the vaccination group and 40.5% of the usual care group (OR, 0.83; 95% CI, 0.70 to 0.99; P=0.037). The number of patients with serious adverse events was also significantly lower in the vaccination group at 52.5% than the usual care group at 59.0% (OR, 0.82; 95% CI, 0.70 to 0.96; P=0.013).
This study has several limitations, including lower levels of influenza activity and higher levels of COVID-19-related mortality in 2021, which may have attenuated the observed effect size initially. The study was also necessarily unblinded, which could have introduced performance or detection bias. The study population, in semi-urban regions of China with historically low levels of community influenza vaccination, may affect generalizability.
BOTTOM LINE: Influenza vaccination before discharge lowers all-cause mortality and rates of hospital readmission in patients hospitalized with acute HF.
CITATION: Anderson CS, et al. Influenza vaccination to improve outcomes for patients with acute heart failure (PANDA II): a multi-regional, seasonal, hospital-based, cluster-randomised, controlled trial in China. Lancet. 2025;406(10507):1020-1031. doi: 10.1016/S0140- 6736(25)01485-0.
Dr. Spinner is a hospitalist and assistant professor of medicine and associate clerkship director in medicine at Columbia University Vagelos College of Physicians and Surgeons in New York.
