The first tier is primary prevention, which are the actions we take to stop people becoming infected in the first place.

第一层是初级预防，这是我们首先采取的阻止人们被感染的行动。

But we also saw this in public health, where targeted tertiary and secondary prevention performed better than more generalized primary prevention.

但我们在公共卫生领域也看到了这一点，有针对性的三级和二级预防比更广泛的一级预防表现更好。