After the U.S.started vaccinating kids for measles in the 1960s, children predictably stopped getting measles.

What happened next had not been predicted - childhood deaths from all infectious diseases plummeted. Even deaths from infections like pneumonia were cut in half. The same phenomenon happened again, in England, and then across Europe and it still happens today when developing countries introduce the measles vaccine.

Why children stopped dying at high rates from numerous and varied infections following introduction of the measles vaccine has been a mystery - but a team of researchers think they have solved it. (Subscription required)

Scientists Crack A 50-Year-Old Mystery About The Measles Vaccine by Michaeleen Doucleff, NPR