Receiving annual vaccination against influenza has been shown to cut death and hospitalization rates for nearly everyone, but the effect is especially dramatic in patients with heart failure, according to a new study.

Getting a flu shot in a given year was associated with a 50% decline in risk of death during flu season and a 20% drop the rest of the year, according to a study presented at the recent American College of Cardiology’s 67th Annual Scientific Session.

Vaccination was also associated with a 22% reduction in the risk of being hospitalized for cardiovascular issues.

The authors, from Nagoya City University Graduate School of Medical Sciences in Japan, tout their study as the first to gauge the relationship between influenza vaccination and death or hospitalization in heart failure patients through meta-analysis.

“It is well known that influenza infection is associated with increased risk for mortality in heart failure patients,” said lead author Hidekatsu Fukuta, MD, a cardiologist at Nagoya City University. “Given the high mortality rate and the relatively low influenza vaccination rates in heart failure patients worldwide, our study supports a wider use of influenza vaccination in heart failure patients.”

Analysis of six studies conducted in the United States, Europe, and Asia—totaling more than 78,000 patients with heart failure—was used to reach those conclusions.

Of the studies, five were observational and one was a retrospective analysis of a clinical trial. No randomized controlled trials designed specifically to investigate influenza vaccination in patients with heart failure were identified.

Pooled analysis of confounder-adjusted hazard ratio indicates that influenza vaccination was associated with reduced risk for mortality during influenza season (risk ratio [95% CI] = 0.52 [0.39-0.69]) and during noninfluenza season (0.79 [0.69-0.90]). Influenza vaccination also was associated with lower risk for cardiovascular hospitalization (risk ratio [95% CI] = 0.78 [0.68-0.89]) but not for all-cause hospitalization (1.00 [0.90-1.11]) during influenza season, according to the data.

Researchers emphasize that heart failure patients are especially susceptible to influenza-related complications, including exacerbation of acute heart failure and secondary infections such as pneumonia.

Yet, results also indicate that the percentage of heart failure patients who receive vaccines varies widely from 26% to 86%, possibly because many guidelines do not address immunization for that population.

Researchers point out that, while the Heart Failure Society of America recommends annual influenza vaccination in all heart failure patients who do not have known contraindications, the ACC/AHA and European Society of Cardiology guidelines do not make such specific recommendations. On the other hand, the CDC recommends that everyone age 6 months and older get a flu shot each year and encourages people with heart disease to stay current on immunizations and talk with their doctor.

“Our meta-analysis suggests the potential mortality benefit of influenza vaccination in heart failure patients,” study authors conclude. “Large-scale randomized controlled trials should be planned to confirm our observed potential survival benefit of influenza vaccination in these patients.