How Vaccines Train the Immune System
The gist
Vaccines work by introducing a safe piece or version of a germ to the body, which trains the immune system to recognize and fight the real germ if it appears later.
Explain like I'm 5
It's like showing your body a picture of a bad guy so it knows who to catch if the bad guy comes to visit.
Big picture
Vaccines help prevent diseases by preparing the immune system in advance, reducing illness and protecting communities through herd immunity.