1.   My guess is that the chance that these vaccines will work is zero.

2.   The latest test results clearly demonstrate that the vaccine works.

3.   The latest tests are a clear demonstration that the vaccine works.

4.   As a result, the company reported little data on how the vaccine might work among those people.

5.   AIDS activists remain hopeful that the vaccine will work.

6.   Both vaccines work by stimulating the immune system to make antibodies against nicotine.

7.   But more likely the vaccine will work to at least some extent.

8.   But other experts say that full-scale tests should be conducted only when laboratory and animal research shows a solid scientific understanding of how an experimental vaccine works.

9.   But the Kenyan researchers are unsure exactly how their vaccine works.

10.   Can a vaccine work?