[_djo_]

Almost no vaccines work that way. They’re not magic shields.

In reality protection is slightly variable depending on a host of factors including age & immune response, but on a _population_ level they work to bring the disease under control.

The polio vaccine ended that disease’s existence in most of the world, but it’s not perfect. If you’re vaccinated with the regular schedule and go to a polio-endemic area you may still get it. That’s why people who may be exposed to it in places where it’s endemic or in labs need additional booster shots according to CDC guidelines.