Last year around this time I got my flu shot feeling pretty proud that A) I actually got it and B) that I was doing my part in making sure that I wasn't going to get the flu (or at least reduce the chances) AND C) that I wouldn't be passing along the flu to my family and coworkers (or at least reduce the chances).

The CDC recommends that we get our flu shot now as flu season starts, preferably before the end of October to help reduce the amount of flu that will circulate.  The CDC's goal is that 70% of adults get yearly vaccine to keep the population healthy.

That afternoon, I had the typical sore arm but, as the evening progressed, I felt really tired, started feeling nauseated and achy.  I checked my temperature and saw that I had developed a fever.  I felt so terrible, like I was having flu symptoms.  I went to bed, slept it off for 14 hours, sweated out the fever, then, felt fine enough to go to work the next day.

So, this year, I did my civic duty and got the flu shot with the fear of this situation repeating itself.  Luckily, no reaction like last year but, I did wonder why did I feel like that?

Browsing through Facebook, I found an article from The Conversation that answered my question: why did I feel like I had the flu the day I got a flu shot?

Here's what I found!

The vaccine that you receive is a dead virus so, when you get your flu shot you are not fighting off the flu.  What really happens when you got your shot is that your body is getting to know the DNA of the dead virus to be ready to fight the real thing, if and when it comes around.

What I experienced was my body reacting to an invader.  It didn't matter that the virus was inactive or dead, what mattered was my body was simply sensing an invader.  While my body was aching, heating up and feeling uneasy, it was building up antibodies to the invader, which should be a close DNA match to the flu strain going around at the time. So, when the active strain comes around, and we all know it will, my body will have built up the antibodies to fight the flu- maybe to avoid it but also maybe to make my flu symptoms not as severe.

So, there it is!  My body was building up antibodies to a foreign invader, like it would with any vaccine you get.  Other theories could be entertained but this is most likely the case, as it would for 2% of the population who gets the flu vaccine.

Want to know more?  Here's the information about the flu shot from a nursing professor from Purdue University, who's run the gambit of frequently asked questions about the flu and here's info about this year's flu shot, including side effects and fun facts.