An international study led by McMaster University researchers and published in The Lancet Global Health has found that influenza vaccines greatly reduce both pneumonia and cardiovascular complications in people with heart failure.
Mark Loeb is a McMaster professor of pathology and molecular medicine and a Hamilton infectious disease physician and microbiologist, and his team found that people with heart failure should get a flu shot because it can save their lives.
The study showed that over the entire year the influenza vaccine reduced pneumonia by 40 per cent and hospitalization by 15 per cent in patients with heart failure. During influenza season in the fall and winter, the influenza vaccine reduced deaths by 20 per cent in these patients.
Data gathered during flu season also showed the vaccine helped protect against cardiovascular complications, such as heart attacks and strokes.
This collaborative clinical trial between McMaster and the Population Health Research Institute of McMaster and Hamilton Health Sciences, had investigators track more than 5,000 patients with heart failure in 10 countries across Africa, Asia and the Middle East where few people have regular influenza vaccination. They received either an influenza vaccine or a placebo annually between June 2015 and November 2021.
While the flu has long been associated with an increased risk of life-threatening cardiovascular events, Loeb said that people with heart failure are already vulnerable to poor health outcomes. Patients with the condition have a 50 percent chance of dying within five years, while 20 percent are hospitalized for cardiovascular complications every year.
Importantly, they looked at low and middle-income countries where 80 percent of cardiovascular disease occurs and where flu vaccination rates are low.
The study is the first clinical trial of the flu vaccine’s effectiveness in patients with heart failure.
Mark Loeb et al. Influenza vaccine to reduce adverse vascular events in patients with heart failure: a multinational randomized, double-blind, placebo-controlled trial. The Lancet Global Health, December 2022 DOI: 10.1016/S2214-109X(22)00432-6
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