Getting a flu shot is like training your body's security guards. The shot puts in some practice enemies so the guards know what to look for. Sometimes, during this practice session, the guards get a little messy and make you feel tired or runny. This is not because you actually caught the flu virus. It just means your body is working hard!
The Practice Run The needle gives you a tiny piece of the flu germ. This piece cannot make you sick because it is broken down. But your body thinks, 'Oh no, an intruder!' and starts sending [soldiers](/search?q=soldiers) to fight it. These soldiers release [chemicals](/search?q=chemicals) that cause soreness or a low fever. It feels like being sick, but you are actually getting stronger!
The Real Flu If you catch the real flu, big bad viruses invade your lungs. They multiply fast and make you feel terrible for weeks. With the shot, only [small pieces](/search?q=small%20pieces) visit your body. They say hello and leave before causing any real trouble.
Examples
- You watch TV with a blanket on because you feel chilly, just like when you are sick.
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See also
- How do mRNA vaccines differ from traditional vaccines in their mechanism?
- How do mRNA vaccines work differently from traditional vaccines?
- How do mRNA vaccines work to protect us from viruses?
- How does mRNA vaccine technology differ from traditional ones?
- How do vaccinations work to protect against diseases?