There are fundamental public health problems, like dirty hands instead of a soap habit, that remain killers only because we can't figure out how to change people's habits.

一些基本的公共卫生问题，例如脏手而不是肥皂习惯，仍然是棘手的问题，仅仅因为我们无法弄清怎么去改变人们的习惯。