‘It is underappreciated that influenza vaccine can save people from cardiovascular death.’
HAMILTON, Ontario — An annual flu shot can help protect the public from influenza, but new research also shows that it can save the lives of those with cardiovascular disease. Besides just stopping many strains of the flu, researchers say influenza vaccines also reduce cardiac complications.
An international study led by scientists at McMaster University has found that flu vaccines greatly reduce both pneumonia and cardiovascular complications among heart failure patients.
“If you have heart failure, you should get your flu shot because it can save your life – that is what we found in this study,” says the study’s principal investigator, Mark Loeb, in a media release.
Loeb is a professor of pathology and molecular medicine at McMaster and a Hamilton infectious disease physician and microbiologist.
“It is underappreciated that influenza vaccine can save people from cardiovascular death,” he adds.
Over the course of an entire year, the influenza vaccine reduced pneumonia by 40 percent and lowered hospitalization rates by 15 percent among patients with heart failure. During flu season (fall-winter), the flu vaccine helped reduce deaths by 20 percent among these patients. Data collected during flu season also indicates the vaccine helped protect against cardiovascular complications, like heart attack or stroke.
Heart failure increases risk of dying within 5 years
This project, a collaborative clinical trial between McMaster and the Population Health Research Institute of McMaster (PHRI) and Hamilton Health Sciences, featured researchers tracking over 5,000 heart failure patients across 10 countries in Africa, Asia, and the Middle East. Those locations are of particular importance considering few people in those regions have regular influenza vaccination access. The patients either received a real influenza vaccine or a placebo annually between June 2015 and November 2021.
Studies have linked the flu to an increased risk of life-threatening cardiovascular issues for quite some time, but Prof. Loeb notes people with heart failure are already vulnerable to poor health outcomes. Heart failure patients have a 50-percent chance of passing away within five years, while 20 percent are hospitalized for cardiovascular complications annually.
“Importantly, we looked at low and middle-income countries where 80 percent of cardiovascular disease occurs and where flu vaccination rates are low,” Loeb says.
“The flu shot should be part of the standard practice in people with heart failure given how simple, inexpensive and safe it is. Avoiding one sixth of deaths from heart disease and preventing hospitalizations makes it very cost effective and that can have an important public health and clinical impact,” adds study co-author Salim Yusuf, executive director of PHRI.
This research is the first clinical trial focusing on the flu vaccine’s effectiveness among heart failure patients.
The study is published in The Lancet Global Health.