How does a vaccination prevent diseases?

I'm doing a science proj (due Mon) and I can't find any info online about how a vaccination prevents disease. Help?

It puts a dead or dying disease right into your bloodstream, so your immune system gets some practice at actually killing the disease, so that the next time you are exposed to it, your body can handle it.

I'll go on to give you (and maybe your teacher) something to think about:

Think of your immune system as a muscle. If you never do anything with it, it gets lazy and weak. Then, when it's actually called upon to do something, it can't. This is why people were healthy back in the old days, before they knew about the spread of disease, and germs. There were diseases, germs and toxins everywhere. And people had these big, strong immune systems that could handle all of them. These days, with all the sanitation, and antimicrobial soaps that we wash with, we've become weak and puny, and can't handle a few germs anymore.

I don't remember the actual percentage, but most of the disease that you are exposed to comes from what your hands pick up during the day. So why would you want to use antibacterial / antimicrobial hand soap, if it's ultimately hurting you?

If you're not in a hospital, working with small children, or preparing food, you should avoid these kinds of soaps. I don't use them at home, and my daughter and I haven't been sick for years. That, in itself, isn't proof of my point, but it is a strong arguement.

This could be part of the reason why cancer is so much more common these days, along with a plethora of other diseases that have been on the rise for years.

http://en.wikipedia.org/wiki/Vaccination

Typically they work with dead or weakened versions of the disease. It helps trigger your immune system to fight off that disease in the future by building you immune system.

Vaccinations are made from dead or weakened viruses, which stimulate the body to put out antibodies against that virus. this way, if the body is attacked by a live virus of that type, the antibodies (which are the primary line of defense against it) are already there.

This is an oversimplified explanation, so I would recommend researching it online or in your textbook:

It works by causing antibodies to build up that will protect you from the disease. The vaccine is made up of proteins of a portion of the dead virus that will not cause illness but will allow your body to build up an immunity to it.

Vaccination introduces either live or dead virus particles into the body. Your body then attacks these particles, creating antibodies against them which will them circulate in your body for the rest of your life. If you encounter the virus again later through transmission, your body is already equipped to fight it off.

These antibodies are also used to test for viral infection. If certain antibodies to a virus are present in your body, then it's often assumed that you are carrying the virus (eg, when someone is determined to be HIV+).

Try looking under measles, mumps and ruebella shots in a search. Vacines work by causing your own immune system to produce anti bodies. Generally vacines are a weaker version or a synthesized form of the virus you are being vacinated for this way your body can fight back on its own.