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Topic #9 – I’m young and healthy. Why do I need a flu shot?

Updated: Aug 28, 2020

Question: The flu is not a big deal. I’m healthy. If I get it, I’ll get over it. Anyways, I’ve heard the flu shot can actually give you the flu so why get one?

Dr. LaSalle: There are several different claims to address here. The first is that the flu isn’t a big deal. This couldn’t be farther from the truth. Tens of thousands of Americans die every year from influenza. It is one of the most deadly vaccine-preventable diseases that we come into contact with.

Prior to a vaccine being developed, influenza was the cause of the most devastating Pandemic in history – the Spanish Flu of 1918. While Spain was the first to report it’s devastation, the Spanish flu actually started in US military barracks and traveled with soldiers around the world, leaving no country untouched. One third of the world’s population was affected and it killed over 50 million people in ONE YEAR.

Thankfully, we now have a vaccine. But misperceptions about the flu virus and about the vaccine itself contribute to the less than ideal acceptance of this vaccine by the general population. While the flu does more commonly severely impact those who are elderly, people who have chronic illness or immune compromise, and infants and children, healthy people also die of complications from influenza.

Studies looking back at children who died from this illness generally show that 40-50% of those kids were completely healthy, without any risk factors for severe disease. And even if it doesn’t kill you, it still results in 100s of thousands of hospitalizations each year, weeks off of work or school, lost wages, and a huge cost to society.

One of the most common claims people hear is that the flu shot can give you the flu. Thankfully, this is not at all true. The flu shot is a killed virus vaccine. There is no live virus in it. It cannot cause the flu.

The flu nasal spray is a different story. It is a live-attenuated vaccine and, if given to someone with a weakened immune system, could give them the flu. Use of the flu nasal spray is much more restricted and it is administered much less commonly than the shot. While we know definitively that the flu shot does NOT cause the flu, there are a few scenarios that can occur that might make someone think that they got the flu from the flu shot. Here’s what can happen.

First, any vaccine can make you feel a bit under the weather. Vaccines work by inducing an immune response. This can make us a bit achy, fatigued, sometimes even give us a low grade fever. But this is considered normal. This is just your immune system kicking into gear. These symptoms are MUCH less severe than those of the actual flu and they typically resolve within 1-2 days. We, as clinicians, need to be better at warning patients about these possible symptoms so that they know what to expect and don’t assume that the flu shot made them “sick”.

Second, it takes 2 weeks for the flu shot to actually work. So it is possible, especially if you wait to get the vaccine until flu season is already in high swing, to catch the flu after getting your flu shot. It was not the shot itself but the lack of effectiveness in those first two weeks that allowed the virus to take hold. In an ideal world, we get the flu shot in September or October, BEFORE flu season begins.

Finally, the flu shot is not perfect. At it’s best, it prevents about 60% of flu infections. So, even though it doesn’t always prevent the flu, what it does do is make symptoms less severe and prevents hospitalization and death from the flu. We know this by looking back each year at the people who died from influenza. Year over year, nearly 80-90% of these people had NOT had a flu shot.

So, while scientists are working on a more effective and longer-lasting flu vaccine, our current flu shot is the best thing we have to prevent the serious and potentially deadly complications of influenza.

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