August 27, 2015

UNSW study finds flu jab provides significant protection against heart attacks

If you’re over 50 and get the flu jab, you’ll not only help to keep the dreaded lurgy at bay but you could also reduce your risk of a heart attack.

That is the advice of UNSW researchers after their study estimated a vaccine effectiveness of 29% in preventing heart attacks which is on par with other heart attack preventative measures.

Previous studies have estimated the effectiveness of statins for the secondary prevention of heart attacks at 25%, anti-hypertensives (15-18%) and smoking cessation interventions (26%).

Researchers in the School of Public Health and Community Medicine (SPHCM) conducted a systematic review and meta-analysis of 16 international case control studies to estimate the association of influenza and vaccination with heart attacks.

They found significant associations between influenza infection and heart attacks, with heart attack patients twice as likely to have recently had the flu. Their review also confirmed existing evidence, including their own 2013 study, which found that the flu vaccination could lower the risk of a heart attack by 45%.

The study was published today in the journal Heart.

Professor Raina MacIntyre, senior author and head of SPHCM, says the population health impact of the flu vaccine on preventing heart attacks could be substantial if a recommendation was made for universal vaccination for people aged over 50.

“Extending the flu vaccination program to 50 to 64 year olds has been a policy debate in the past, but not considered to be cost effective,” says Professor MacIntyre.

“However, prevention of cardiovascular disease wasn’t taken into consideration in such estimates.”

People aged 50 to 64 are currently not routinely included in national flu vaccination programs, however they are in the at-risk age group for heart attacks.

Professor MacIntyre says hidden heart disease lurks in many healthy-looking middle-aged Australians.

“Even if you’re a healthy weight and you’ve no family history of heart attacks, you may have some thickening of your arteries without knowing it,” she says.

“A flu vaccine is safe, effective and is not expensive. Based on this study’s findings, I would recommend the flu jab for anyone over 50 regardless if they are at risk of heart disease.”

Previous research indicates that infections such as the flu might encourage blood to thicken or prompt an inflammatory response in arteries that are already diseased, and trigger a blockage in a partially blocked artery.

Heart attacks are the leading cause of death and disability globally. Each year, around 54,000 Australians suffer a heart attack and in 2013, heart attacks claimed 8,611 Australian lives.

The researchers are now calling for a large-scale randomised controlled trial to provide conclusive evidence of the protective effect of influenza vaccination on heart attacks, including as a primary prevention tool.

The study supports the findings of a 2013 case control study by UNSW researchers that examined the association of influenza and flu vaccination with heart attacks over three winter seasons in Sydney, from 2008 to 2010. This study formed part of the current meta-analysis and systemic review.

This latest study adds to the growing body of evidence, including animal studies, observational studies and randomised controlled trials, which have investigated the relationship between influenza infection and a subsequent heart attack and the protective effect of influenza vaccination on heart attacks.