由于疫苗的作用，5岁前夭折的儿童数量从1960年的2000万降至2011年的690万，而且这是在地球人口大量增长的条件下实现的。
Thanks in large part to the power of vaccines, the number of children dying before the age of five has fallen from 20 million in 1960 to 6.9 million in 2011, despite a large increase in global population.