31.   The vaccine works unusually fast, saving a person even three or four days after the start of viral infection.

32.   The vaccine may not work.

33.   Therapeutic vaccines work on the principle that patients recovering from cancer operations, for instance, have weakened immune systems.

34.   Vaccines work simply by producing antibodies, right?

35.   VaxGen is the closest to completing a series of human tests and expects to find out early next year whether its vaccine works.

36.   Anthrax vaccine works against germ warfare agent in monkey studies.

37.   Dr. Lawrence Corey of the University of Washington, a herpes expert, raised the possibility the vaccine might not work in people who already have herpes.

38.   Each vaccine works against only one of four strains.

39.   Epstein said the standard vaccine still works against the mutated strain, and that health officials are organizing vaccination efforts in Haiti and the Dominican Republic.

40.   Injected vaccines work in generally the same way.