How vaccines work for the uninitiated.

Seen a lot of people saying "But the vaccine doesn't stop you getting it". This is an absolute misunderstanding of how vaccines work. 

Think of your body like a house. The first time you see an ant in your house you probably add ant spray to your shopping list. But by the time you go to the shop and have the ant spray the ants have been busy and your now have to deal with an infestation. But from then on you keep ant spray in the house and kill any ants you see. Having the ant spray doesn't stop the ants getting in but stops the infestation. Your immune system works in the same way. 

When you get a virus your body starts making antibodies that are specific to that virus. If it's never seen it before it has to work out how to build those anti bodies and by the time it has the virus has multiplied to a point where you are sick. So a vaccine gives it enough information to learn how to build the antibody and trains it for when it encounters the virus. Then the next time that virus is in your body you can make the antibodies much faster than if it hadn't ever seen that virus before. But you will still have caught the virus. Your body can't kill it before it's in your body just stop it from multiplying to the point where it makes you sick.