ATLANTA - The bird flu vaccine currently being manufactured fought at least two forms of the virus in mice, but it's unclear whether the drug would be equally effective in humans, a health official said Monday.

The vaccine was designed to combat a version of bird flu identified in Vietnam in 2003. Scientists have wondered whether it also offers protection against a version seen later in Indonesia, Europe and Africa.

Experiments have shown that in mice, the vaccine for the first version prevented proliferation of the second, said Dr. Nancy Cox, director of the influenza branch of the federal Centers for Disease Control and Prevention.

注释：

1、bird flu：禽流感
2、vaccine：n. 疫苗
3、virus：n. 病毒
4、effective：adj. 有效的
5、combat：v. 抗击
6、version：n. 样式、形式
7、identify：v. 识别、鉴别
8、prevent：v. 防止、预防
9、proliferation：n. 增殖、分芽繁殖
10、influenza：n. 流行性感冒
11、Centers for Disease Control and Prevention：美国疾病控制和预防中心