Source: Radio New Zealand
The vaccine’s protection against heart issues comes directly from reducing the risk and severity of influenza. File photo. CDC
Getting an annual influenza vaccine can reduce the risk of a heart attack or stroke by a third, according to the Immunisation Advisory Centre.
The centre said there was a growing amount of evidence which showed that getting the vaccine was about as effective as using common heart medication.
Heart disease and stroke are the leading causes of death in New Zealand, accounting for 12,000 deaths per year.
Since 2003, strong evidence has emerged demonstrating that the flu vaccine offered substantial cardiovascular protection.
This protection comes directly from reducing the risk and severity of influenza, plus likely further non-specific immune protection.
Dr Philip Shirley from the Immunisation Advisory Centre told Midday Report that it had been known for about 100 years that in a really bad flu season the number of people having heart attacks and strokes increased.
“More recently we’ve been able to show that if you take a swab of someone in the community and they have influenza, they’ve got a six to 10 times the base rate of having a heart attack for the next seven to 10 days after they’re proven to have influenza.”
That happened for two reasons, he said.
The first was if you catch the flu it goes into your nose and then your chest, he said.
“From there the virus can actually relocate, so into your heart and when it gets to your heart it can cause conditions like myocarditis, peridcarditis, kind of inflammation of the heart, but even more concerning it can actually move into the blood vessels.
“When it’s in the blood vessels it can disrupt plaques that are here and disrupted plaques are what causes heart attacks because they rupture, they block the blood vessel, and that’s a heart attack. If it happens in the brain then it’s a stroke.”
Another issue was that the lungs of those suffering from severe influenza did not transport oxygen as well as usual, he said.
“And because your lungs aren’t working properly your heart starts beating faster and harder and that’s a problem – that increases your risk.”
The main way that the influenza vaccine protects people is because it protects you from getting influenza which can cause heart attacks and strokes, he said.
The influenza vaccination also “changes the way that the heart responds to stress and inflammation”, he said.
“They did some really interesting studies where people undergoing open heart surgery, some of them had an influenza vaccine the week before, some of them didn’t.
“And when you measure their inflammatory markers after the operation, the people who had the flu vaccine had less inflammation and they showed less signs of heart stress, after one of the most stressful things you can do to your heart.”
A third way the vaccine helps protect people was with “trained immunity”.
“I think of it like this – if our immune system is responding to things frequently, if we’re getting vaccinated regularly, then the immune system gets stronger, not just against the target disease, but it protects you from a wide range of bio-illnesses.
“Nearly any illness you catch can increase your risk of having a heart attack or a stroke – not as badly as influenza, but it can a bit. And getting the flu vaccine every year seems to protect you from lots of respiratory illnesses.”
Dr Shirley said the biggest benefits of getting the vaccine would be for those with chronic health conditions or were over the age of 65, but there were also benefits for healthier people.
“If you’re a healthy person, getting influenza is no picnic. Your rate of heart attacks and strokes might be low, but even increasing a low risk of heart attacks or strokes by six or 10 times isn’t something I would want to be doing.”
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– Published by EveningReport.nz and AsiaPacificReport.nz, see: MIL OSI in partnership with Radio New Zealand
LiveNews: https://nz.mil-osi.com/2026/03/25/how-an-annual-influenza-vaccine-can-reduce-the-risk-of-heart-issues/