For example, even as late as 1970, only around 5% of infants were vaccinated against measles, tetanus, whooping cough, diphtheria, and polio. By 2000, it was 85%, saving about three million lives annually – more, each year, than world peace would have saved in the twentieth century.
最大的因素是婴儿死亡率的下降。比如，晚至1970年，能够接种麻疹、强直、百日咳、白喉和脊髓灰质炎疫苗的婴儿也只有5%左右。2000年，这一比例为85%，每年能拯救约三百万生命，比20世纪世界和平所拯救的生命数量还要多。