In May 1980, it was confirmed that mankind had eradicated smallpox; since then, the smallpox virus has only continued to exist in the form of samples retained at three medical research centers in the UK, the US and the USSR.
一九八○年，人類根除了危害已久的痘病毒感染症﹘﹘天花，全世界除了英、美、蘇三個醫學研究中心還存有天花病毒外，天花病毒已在地球上消失。