Your immune system works by making large molecules called antibodies, and these go around your blood looking for trouble. Trouble means stuff the body doesn’t recognise. The body knows what its own cells look like, and if everything is working OK, the body doesn’t attack itself. But if the antibodies recognise something different or unusual they stick to it. The sticking process sends out a signal that something has happened and the body starts making more of that antibody. The antibodies stick more and more onto the alien thing and that signals the body to start destroying the thing the antibodies stuck to.
Very clever.
So what you do with a vaccination is this. You find out whatever causes a disease. Let’s say it’s a virus. You get a sample of that virus. Then you kill the virus somehow, without totally destroying what it looks like. Sometimes you can blast it with lots of radiation, so the insides are ruined, but the outside (the “capsid”) is still OK. Now you can take some of this “deactivated” virus and inject it into the body (that’s the vaccination). The body recognises it, and kills it, but because it wasn’t an active virus, you don’t get sick.
The clever bit is that your immune system has a memory. The antibody that bound to the virus – it’s kept around by the body for a while, just in case that virus comes back. So if the REAL virus comes along, and starts to try to cause trouble, the body quickly spots it and takes it out. The virus doesn’t have time to cause any trouble.
The memory of the vaccination fades over the years. That’s why you sometimes need “boosters” like with the tetanus vaccination.
Vaccination was discovered in the 1700s by a scientist named Edward Jenner. He noticed that milkmaids (who milked cows each day) had sores on their hands from cowpox, but never became sick with smallpox, a virus which was causing a lot of very unpleasant disease at the time (check out a picture: http://en.wikipedia.org/wiki/File:Child_with_Smallpox_Bangladesh.jpg)
He realised that the previous infection with cowpox meant that the milkmaids would not get smallpox, so he decided to test his theory. He infected a young boy with the cowpox virus (I don’t know where that boy’s parents were or why they let him do it!) then with the smallpox virus to see if the boy would become sick. The boy was safe from smallpox infection, so cowpox was given to people as the first vaccine against smallpox.
Cowpox protected against smallpox because the viruses look similar to the body. Our immune system has lots of special cells which recognise and fight infections. One of these cell types produces molecules called antibodies. It takes a couple of days to make these antibodies, so it takes a while to have them ready to kill the bugs that are infecting you. Once they’ve been made, these antibodies will hang around in the body for several years or even the rest of your life. So if you become infected by the same bug again (or a very similar one) then the antibodies are ready to go and the infection can be cleared quickly.
Vaccination gives us a head start. The vaccine contains little bits of a virus or bacteria, or even the whole thing that has been treated so it is not harmful anymore. When it’s injected into our body we start to produce antibodies, which then stay in our body. If the real thing comes along and infects you, then you’re already prepared to fight it off, so the infection will be less severe, or you might not even get sick at all!
Your immune system works by making large molecules called antibodies, and these go around your blood looking for trouble. Trouble means stuff the body doesn’t recognise. The body knows what its own cells look like, and if everything is working OK, the body doesn’t attack itself. But if the antibodies recognise something different or unusual they stick to it. The sticking process sends out a signal that something has happened and the body starts making more of that antibody. The antibodies stick more and more onto the alien thing and that signals the body to start destroying the thing the antibodies stuck to.
Very clever.
So what you do with a vaccination is this. You find out whatever causes a disease. Let’s say it’s a virus. You get a sample of that virus. Then you kill the virus somehow, without totally destroying what it looks like. Sometimes you can blast it with lots of radiation, so the insides are ruined, but the outside (the “capsid”) is still OK. Now you can take some of this “deactivated” virus and inject it into the body (that’s the vaccination). The body recognises it, and kills it, but because it wasn’t an active virus, you don’t get sick.
The clever bit is that your immune system has a memory. The antibody that bound to the virus – it’s kept around by the body for a while, just in case that virus comes back. So if the REAL virus comes along, and starts to try to cause trouble, the body quickly spots it and takes it out. The virus doesn’t have time to cause any trouble.
The memory of the vaccination fades over the years. That’s why you sometimes need “boosters” like with the tetanus vaccination.
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Vaccination was discovered in the 1700s by a scientist named Edward Jenner. He noticed that milkmaids (who milked cows each day) had sores on their hands from cowpox, but never became sick with smallpox, a virus which was causing a lot of very unpleasant disease at the time (check out a picture: http://en.wikipedia.org/wiki/File:Child_with_Smallpox_Bangladesh.jpg)
He realised that the previous infection with cowpox meant that the milkmaids would not get smallpox, so he decided to test his theory. He infected a young boy with the cowpox virus (I don’t know where that boy’s parents were or why they let him do it!) then with the smallpox virus to see if the boy would become sick. The boy was safe from smallpox infection, so cowpox was given to people as the first vaccine against smallpox.
Cowpox protected against smallpox because the viruses look similar to the body. Our immune system has lots of special cells which recognise and fight infections. One of these cell types produces molecules called antibodies. It takes a couple of days to make these antibodies, so it takes a while to have them ready to kill the bugs that are infecting you. Once they’ve been made, these antibodies will hang around in the body for several years or even the rest of your life. So if you become infected by the same bug again (or a very similar one) then the antibodies are ready to go and the infection can be cleared quickly.
Vaccination gives us a head start. The vaccine contains little bits of a virus or bacteria, or even the whole thing that has been treated so it is not harmful anymore. When it’s injected into our body we start to produce antibodies, which then stay in our body. If the real thing comes along and infects you, then you’re already prepared to fight it off, so the infection will be less severe, or you might not even get sick at all!
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