eli5- why do you get a tetanus shot even after you cut yourself with something rusty?

Question

If shots (vaccines) are supposed to simulate the infection before getting the real thing, why does it work after you get the actual virus in your body

In: 1

Answer 1

Tentanus is not a virus but a bacteria. The vaccine works in the same way as for a virus though. When you get an infection it is usually down to just a few cells. The viral load is very small. So your immune system might not notice the infection at first. Especially for bacteria it takes some time for the infection to multiply and spread. But a vaccine have a very high viral load spreading vast amounts of proteins throughout the blood system in seconds. The immune system will trigger immediately and start making antibodies to fight the vaccine. So when the infection finally gets a hold the immune system is full of antibodies and already highly active.