Protecting Your Heart Is a Pain in the... Arm

"Is it me, or did this year's flu shot hurt more?"

It's a question we heard a lot last week during our company's annual health fair. Amidst the tables offering blood pressure screenings and free smoothies, there was a long line for flu shots.

But many of the folks who opted for the annual vaccine later wondered why it hurt more than previous years' shots.

Flu shots often come with a small amount of pain. And that's a good thing. It means that your body is reacting to the introduced viruses and is already making antibodies to fight them. That's how the flu vaccine works – it introduces a few strains of the flu virus (usually three or four) in small doses. They're nearly always deactivated as well, to ensure you won't get a full-blown infection.

Introducing these tiny samples of the flu virus trains your immune system to fight them. It also means you'll make antibodies that can identify and fight off these same strains if you encounter them again.

So if your arm is stiff, red, or warm, that's good news. Your body is mounting an immune-system attack that will create those antibodies and give you protection from future exposure.

Some years, it might hurt worse. That can happen if you've already been vaccinated for (or already contracted) one of the viruses in the shot.

The annual vaccine in the U.S. changes each year based on which strains were the most contracted in Australia, where flu season happens during our summer months. The shot typically contains strains of influenza A and influenza B – the types that cause the most serious infections.

In the 2019-2020 flu shot, you'll find components of two influenza-B strains: B/Victoria and B/Yamagata. These influenza-B strains are the same ones that were in the 2018-2019 flu shot. In other words, your body recognized these viruses and launched the antibodies immediately, which can lead to a bit more pain.

But a sore arm is just one of the lesser side effects of flu shots. The benefits are higher... especially now.

Longtime readers know I've balked at getting a flu shot for years. But in 2017, I changed my mind because of new research on the benefits for heart protection that the vaccine provides. Folks who regularly get the flu shot lower their risk for a heart attack.

Fighting off influenza stresses your immune system. When you're fighting off the virus, inflammation increases, particularly in your blood vessels.

More and more studies show that increases in inflammation lead to blockages... which ultimately leads to heart attacks or strokes.

What's more, the flu causes your blood vessels to leak fluid, which builds up in your lungs. That fluid may start to grow bacteria, causing deadly infections. It also means you're getting less oxygen into your blood. That in turn puts a strain on your heart.

But what about long-term protection?

It turns out that when your body creates antibodies to the flu vaccine, those antibodies flip on a receptor in our heart. It's called the bradykinin 2 receptor. The protein it works with, bradykinin, is an inflammatory marker. Triggering this receptor reduces inflammation and seemingly protects heart tissue.

Researchers are now studying different types of flu vaccines to develop a possible heart-disease vaccine. This is really exciting. Regular readers and friends know I've long thought that most diseases we face are infectious. I've been laughed at because of my thoughts about the connection between infection and diseases like heart disease and age-related macular degeneration.

The vaccine also offers some protection against getting the flu, though some folks are quick to point out low effectiveness rates. These rates don't measure one important outcome, though – fewer hospitalizations and deaths. You might still get the flu, but the vaccine will reduce your symptoms and help you avoid the most serious outcomes.

As we get into flu season, consider getting your vaccine. I still advise that if you're a healthy adult – without heart disease risk factors – chances are you don't need the vaccine. But if you're in a group that's at a higher risk for complications, you should get a flu shot. That includes:

  • Folks age 65 and older
  • Those with a compromised immune system (including autoimmune diseases like Crohn's and those undergoing cancer treatments)
  • Those who have heart disease or are at risk of heart attack
  • Pregnant women
  • Babies and young children

Similarly, if you're around someone who falls into one of these groups, consider getting a vaccine. For instance, if you're caring for someone recovering from chemotherapy, you don't want to risk exposing them. Complications for these folks can be life-threatening or fatal.

What We're Reading...

Here's to our health, wealth, and a great retirement,

Dr. David Eifrig and the Health & Wealth Bulletin Research Team
October 22, 2019