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How does the flu vaccine actually work?

To understand how the flu vaccine works, you need to understand how your immune system works.

I feel compelled by duty to my profession to type this out. Please, share the heck out of this, because people need to know this stuff.


How do vaccines work?

To understand how the flu vaccine works, you need to understand how your immune system works first. Your immune system fights disease by remembering every single disease you’ve ever seen in your life. Seriously. Every one of them. In response, your body makes antibodies that tell your white blood cells which infections need to be destroyed. If it helps, think of antibodies as the blue ink that explodes if somebody tries to steal something; now we all know who the thief is.

Your body can crank out antibodies at a moment’s notice for any disease you’ve ever come into contact with; they tag the offending bacteria or virus and your white blood cells come in and the offender dies a horrible death.

Vaccines work by “training” your body’s immune system. There are two types of vaccines: inactivated, and live/attenuated. Inactivated vaccines are essentially the protein coat of whatever you’re trying to vaccinate against. Think of it as what the bacteria or virus is “wearing.” Live/attenuated vaccines are viruses or bacteria that have been weakened. The vaccine isn’t what the virus is “wearing,” it’s just a really weak version of the virus itself.


Your immune system is like an army

Think of your body’s immune system as an army. Giving an inactivated vaccine is like holding up the uniform of an enemy soldier in front of your body’s immune system and saying, “See this, everybody? You go seek and destroy everybody wearing this.” Giving a live/attenuated vaccine is like finding an enemy soldier, beating the crap out of him and putting it in front of your body’s immune system and saying, “See this guy right here? You go beat the hell out of anything and anybody who looks like him.” Now, if somebody has a compromised immune system, the beat-up bad guy can still cause a lot of damage, which is why people who are immunocompromised or have a weak immune system shouldn’t get live/attenuated vaccines.

So is the flu vaccine live? No. The flu vaccine is inactivated; it’s dead. It is nothing more than the protein coat of influenza with all of the DNA removed. It is an empty shell of a uniform.


Why do I need to get a flu shot?

Every year, the Flu be like…

Here’s why you have to get a flu shot every year: The flu changes its protein coat on a regular basis. The flu has fashion sensibilities not unlike ours; the flu changes its “look” every year. Basically, at this time next year, the flu is going to be wearing a different uniform, and getting a flu shot is the best chance you have to avoid influenza.

The CDC and all sorts of scientists try to forecast what the flu will be “wearing” from year to year and, yes, sometimes they get it wrong because that job is REALLY FREAKING HARD. I couldn’t do it. I once predicted JaMarcus Russell was going to be a good NFL quarterback, so my predicting is pretty bad. Trying to anticipate, replicate, and mass produce a flu viruses protein coat over about a four-month period seems to be one of the most difficult and thankless jobs in the United States.

You can’t get the flu from the flu shot. You could get flu vaccine side effects in the form of an immune response…I’ve had one of those. I’ve also had the flu. The two aren’t even close to the same thing. Not the same ballpark, not the same league, they ain’t even the same bleeping sport. I got the flu in 2005 and it was as sick as I’ve ever been and lasted a month. I got an immune response in 2010 and it lasted 12 hours and required an extra blanket while I watched Monday Night Football.

This is how the flu shot works. This is how your immune system works. If you were lucky enough to be gifted a healthy immune system, you were gifted one of the most amazing things that exists. Vaccines help your immune system do its thing better. This isn’t fake news, it isn’t alternative facts, it’s the truth.


The expert family medicine providers at the Des Moines University Clinic can help you and your loved ones stay healthy during flu season and beyond. For more information or to make an appointment, visit the DMU Clinic website or call 515-271-1710.

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Jonathan Crosbie, D.O.

Dr. Crosbie is an assistant professor in the Departments of Osteopathic Medicine and Family and Internal Medicine at Des Moines University. In addition to his academic responsibilities and providing excellent patient care in the Family Medicine Clinic he is an avid activist for preventative medicine and living a healthy lifestyle. In his spare time he enjoys motorcycling, woodworking, movies and sports, and spending time with his family.

Posted in ,

Jonathan Crosbie, D.O.

Dr. Crosbie is an assistant professor in the Departments of Osteopathic Medicine and Family and Internal Medicine at Des Moines University. In addition to his academic responsibilities and providing excellent patient care in the Family Medicine Clinic he is an avid activist for preventative medicine and living a healthy lifestyle. In his spare time he enjoys motorcycling, woodworking, movies and sports, and spending time with his family.

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