How do vaccines work? Well, vaccines are basically a stupendously brilliant way to train ourselves to fight some downright nasty, even deadly diseases.
Let me explain. When we get sick from viruses or bacteria, our immune system creates weapons that attack the invading germs, but every disease is a little different, so we need to develop unique ammo for each one.
And that can take time, which we don't always have. Some infections work fast and furious, never really giving us a chance to defend ourselves and the results can be deadly.
The genius of vaccines is that they get our bodies to prep defense strategies without us having to actually get sick. Many do it by carrying a weaker or dead version of the germ, just enough to signal to our body to go on the attack, but not so much that an infection flares up.
Our immune system then remembers the strategy for each defense. That way if you ever come face to face with the real thing, we can get the upper hand by quickly pulling together a deadly strike force of our own. Many vaccines provide lifelong protection and though none is 100% effective, the more people in a population that get vaccinated the more we're able to control diseases.
Thanks to vaccines smallpox is a thing of the past.