Misadvertising vaccines as "safe and effective"

MMR Vaccine safety insert

I still don't understand. If vaccines are safe and effective then why do they come with an insert which basically says vaccines are unsafe and untested and can cause a whole host of problems?

If they were really safe they wouldn't need such an insert, and if they were really effective people wouldn't be worried about unvaccinated children infecting their own vaccinated children.

It really makes no sense, and perhaps that is on purpose to confuse people.