Judy Woodruff:

Now another aspect at the world's largest humanitarian crisis. It comes through the story of one family that has borne astonishing loss, and is trying to prevent even more from the preventable disease diphtheria.

And though it's been eradicated in many parts of the world through vaccination, the public health crisis caused by Yemen's war has let this infection flourish there for the first time since 1989.

From Aden, special correspondent Beth Murphy reports.