Daniel knows he has had vaccines. He never really understood what they were doing inside his body.

So he asked.

The explanation starts with something simple. A vaccine is a fire drill for your immune system. It gives your immune system a safe preview of something that represents a threat but cannot give you that disease, so that when the real thing arrives, your body is better prepared to fight it.

mRNA vaccines do that in a specific and elegant way. Instead of giving your immune system a weakened pathogen or a harmless piece of one, they give your cells a temporary set of instructions. Instructions to briefly make one specific protein, a small harmless piece of the virus, so the immune system can learn to recognize it. After that, the instructions naturally break down. They do not remain in your body permanently. Your cells sto ...