[tlb]

Why wouldn't you ask for liability protection? No matter how safe, like even if the injection was actually pure water, thousands of people would be convinced they were injured and sue for millions which, even if you won every case, costs a fortune in legal fees.

No vaccine is perfect. They work by showing your immune system some example germ features, and most people's immune systems learn to defend against them. But immune systems are extremely complex and variable between people, and you can never guarantee a particular response.

Vaccines sometimes completely eliminate some diseases (smallpox is one). They do this not by giving every person 100% protection individually, but by reducing transmission enough that the germ dies out.