Tips From The Professor: Flu Shots & Heart Attack Risk

You’ve seen the recent headlines: “Study Finds Flu Shot Cuts Heart Attack Risk in Half”. These headlines refer to a currently unpublished study presented late last year at the 2012 Canadian Cardiovascular Congress.

The study analyzed the results of published clinical trials involving a total of 3,227 patients, average age of 60, half of whom had already been diagnosed with heart disease. They were randomly assigned to receive either a flu shot or placebo shot and their health was tracked for 12 months. And the study found that the flu shot was associated with a 50% reduction in heart attacks and stoke and a 40% reduction in cardiovascular death.

That’s enough to make you want to want to rush out and get your flu shot right away, which is what many of the media reports suggested you should do.

However, while that sounds very impressive, the number of people in those groups experiencing a heart attack or stroke during the 12 month period was small, which limits the strength of the conclusion.

In addition, half of the people in that study already had heart disease. Two previous studies in populations without previous evidence of heart disease have had mixed results. One study (CMAJ, 182: 1617-1623, 2010) found that the flu shot was associated with a 20% reduction in heart attack risk, while another study (Hum Vaccin, 2: 161-166, 2006) found no correlation between flu shots and heart attack risk.

So, all the hype about this recent study is a bit misleading. The flu shot has always made sense for the very old and very sick. If you have a serious heart condition, or if you are old and feeble, a bout of the flu can push you over the edge. So while it is true that the flu shot significantly decreases the risk of dying from a heart attack, many of those people would have kicked the bucket in a year or two anyway. Of course, no one wants to die prematurely – even a little bit prematurely, so it is absolutely correct to say that flu shots reduce heart attack deaths and save lives in that population group.

Where it is not so clear the flu shot is beneficial, is for the young and healthy. The flu shot offers few benefits and a very slight risk for that population group.

For the young and healthy group flu shots primarily make sense from a public health standpoint. The very old and the very sick often have weak immune systems, so the flu shot is not particularly effective for them. However, if public health officials can convince every else to get their flu shots, the probability of the old and sick getting exposed to the flu virus is decreased and you will decrease death from flu in that population.

So what is the bottom line for you?

If you are old, have a weakened immune system, or have major diseases such as heart disease, diabetes or hypertension, the flu shot makes a great deal of sense.

If you are young and healthy, you have a choice. We do many things in this life for altruistic reasons – things that help other people without providing any direct benefits to us. If you are young and healthy the flu shot is like that. It’s something you might do because it could save the life of someone who you might otherwise expose to the flu virus.

I just wish that were the message that we heard from public health officials. I believe in truth in advertising.

To Your Health!

Dr. Stephen G Chaney

What do you think?