Psychologists are designing how to get vaccine acceptance rates up.
When a parent brings their kids in, instead of saying "I recommend vaccinating for 7 diseases today.", you can say "Your child needs 3 shots while he's here.". 
By turning it into a command and making it sound like you're doing less, you increase compliance.
Even though the person is free to leave and not do anything, fewer will.
It's kind of sad, really, that they've decided to resort to twisted psychology instead of educating people that these are good vaccines against some really nasty shit and then relying on rational people making an informed decision.
Such is life.