Getting the flu shot reduces your risk of stroke years later, study finds

Getting the flu shot reduces your risk of stroke years later, study finds

  • Getting the flu shot reduced the risk of stroke by more than 20%
  • Influenza infection is thought to increase a person’s risk of having a stroke
  • Large-scale influenza vaccination may be a viable public health strategy to prevent strokes

Getting the flu shot could be more important than ever – a study says it also reduces the risk of stroke years later.

Researchers say health officials should push harder for everyone to get routine flu shots rather than just the most vulnerable.

The study analyzed the health records of more than 4 million adults in Alberta, Canada, over a 10-year period.

The results showed that people who got the flu shot once a year or every flu season over a 10-year period reduced their risk of stroke by more than a fifth on average.

The protective effect was even more marked in men and young people.

Researchers haven’t specifically investigated why getting the flu shot significantly reduces risk, but the prevailing hypothesis is simple.

The vaccine reduces the risk of catching and getting sick from the flu, which is a known risk factor for stroke.

Getting the flu shot could be more important than ever – study says it also reduces risk of stroke years later

Getting the flu shot could be more important than ever – study says it also reduces risk of stroke years later

People who received a flu shot either once a year or every flu season over the 10-year period reduced the risk of stroke by about 23% in individuals of all adult ages

People who received a flu shot either once a year or every flu season over the 10-year period reduced the risk of stroke by about 23% in individuals of all adult ages

THE CAUSES OF STROKE

There are two main types of stroke:

1. ISCHEMIC STROKE

An ischemic stroke – which accounts for 80% of strokes – occurs when there is a blockage in a blood vessel that prevents blood from reaching part of the brain.

2. HEMORRHAGIC STROKE

The rarest, a hemorrhagic stroke, occurs when a blood vessel bursts, flooding part of the brain with too much blood while depriving other areas of adequate blood supply.

It can be the result of an AVM or an arteriovenous malformation (an abnormal group of blood vessels) in the brain.

Thirty percent of people with subarachnoid hemorrhage die before they reach hospital. Another 25% die within 24 hours. And 40% of survivors die within a week.

RISK FACTORS

Age, high blood pressure, smoking, obesity, physical inactivity, diabetes, atrial fibrillation, family history and history of stroke or TIA (mini-stroke) are all risk factors of stroke.

SYMPTOMS OF A STROKE

  • Sudden numbness or weakness of the face, arm, or leg, especially on one side of the body
  • Sudden confusion, difficulty speaking or understanding
  • Sudden difficulty seeing or blurred vision in one or both eyes
  • Sudden difficulty walking, dizziness, loss of balance or coordination
  • Severe, sudden headaches with no known cause

RESULTS

Of the approximately three out of four people who survive a stroke, many will have lifelong disabilities.

This includes difficulty walking, communicating, eating, and performing everyday chores or tasks.

TREATMENT

Both are life-threatening, and patients need surgery or a drug called tPA (tissue plasminogen activator) within three hours to save them.

The study’s lead author, Dr Michael Hill, from the University of Calgary, said: ‘We wanted to find out if the vaccine had the same protective qualities for people at risk of stroke.

“Our results show that the risk of stroke is lower in people who have recently received a flu shot. This was true for all adults, not just those at high risk of having a stroke.

The researchers reviewed patient records using administrative data from Alberta’s public health insurance system.

This is the largest study of flu vaccination and stroke risk to date, scientists say.

The overall risk reduction was about 23% for individuals of all adult ages, male and female.

But the reduction was greater in men than in women – 28% versus 17% – and strongest in young people.

The researchers believe that the lower relative reduction in risk in the elderly may be related to the decreased biological response to vaccination in the elderly.

The immune response to vaccination is reduced in the elderly compared to healthy young adults.

Older people also have an increased risk of stroke.

Previous research suggests that catching and getting sick from the flu can increase the risk of stroke and other heart problems.

Scientists point out that when flu cases increase, stroke cases typically increase three weeks later.

They think the immune response to the flu thickens the blood and inflames the arteries, leaving people more prone to clots.

“There’s a long history between infections and strokes – upper respiratory tract infections are associated with strokes – so it was quite natural to start looking at that,” Dr Hill said.

“There is a relationship between influenza and myocardial infarction – heart attacks – so establishing the links with stroke was a natural next step.”

The study was published earlier this week in the Lancet Public Health.

Strokes occur when blood flow to the brain is interrupted or cut off.

Stroke is one of the leading causes of disability in the United States. Stroke victims often suffer from paralysis, loss of mobility and speech impairment.

Although a stroke is treatable, time is running out.

The sooner a stroke victim sees a doctor, the more effective drugs can be at restoring blood flow to the brain and reversing damage.

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