美国北卡罗来纳州大学免疫学家的研究表明 ,35年前的天花疫苗接种仍能提供重要保护作用。这一结果很重要 ,因为人们担心恐怖分子会用天花病毒作为战争武器。　　自 1 980年世界卫生组织宣布天花消灭以后 ,免疫接种停止 ,使大多数年轻人成为易感者。据说天花病毒仅存放于美国和 Studies by immunologists at the University of North Carolina in the United States have shown that smallpox vaccination 35 years ago can still provide important protection. This result is important because people fear that terrorists will use VARV as a weapon of war. Since the World Health Organization announced the eradication of smallpox in 1980, immunization ceased and most of the youth became susceptible. It is said that VARV is only stored in the United States