Mao Zedong’s Four Pests campaign has to rank as the most disastrous entirely successful public health policy ever. It pulled together every part of society to meet its goals, which it surpassed to an astonishing degree—and half of those goals almost certainly resulted in major widespread improvements to the health of the nation. Two out of four isn’t bad, you might think.
The trouble is that the fourth goal resulted in tens of millions of deaths.