Our age likes to believe in the inevitability of human progress, but for an example of the opposite consider the Pacific island nation of Samoa. A measles outbreak there has already killed more than 60 people, and authorities declared a two-day curfew on Thursday and Friday.

Businesses were obliged to close and vehicles had to stay off the roads from 7 a.m. to 5 p.m. Mike Cherney of The Journal reports that residents were told to fly red banners from their homes if anyone inside needed vaccinations in the country of roughly...