translation.en: But this was in 1974, and as of that moment, this photograph was the photograph that was the most widely printed, because we printed two billion copies of this photograph, and we took them hand to hand, door to door, to show people and ask them if there was smallpox in their house, because that was our surveillance system.
translation.zh: 但是在1974年 在那个时候，这张图片是 印刷最多的 我们一共印了二十亿张 而后是逐家逐户的发放 向人们询问他们家里是否有天花病人 这就是我们的监控系统。我们那时候没有Google