The World Health Organization declared swine flu as the first international pandemic of the century on Thursday and urged nations to step up the fight against the virus. 世界卫生组织周二宣布甲型流感成为本世纪第一次全球范围流感大流行，敦促各国升级对抗甲型流感病毒的斗争。
Genetic analysis of the new swine flu virus has shown that it differs dramatically from previous seasonal viruses. 新甲型流感的遗传学特性分析表明其与之前的季节性病毒有极大不同。
