11.   The so-called acellular pertussis vaccines use only a piece of killed pertussis bacteria instead of the whole cell used in older vaccines.

12.   The so-called acellular pertussis vaccines use only a piece of the pertussis bacteria, thereby gaining the benefit of immunization without as many side effects.

13.   The vaccine uses a genetically engineered adenovirus, a microbe that causes the common cold.

14.   The vaccine uses microscopic engineering to precisely target certain white blood cells in the body against specific cancerous targets.

15.   This vaccine uses a whole cell of pertussis bacteria that is inactivated, usually with heat.

16.   While there are fewer than two dozen vaccines commonly used in the U.S., five times that number are in development.

17.   Researchers writing Friday in the journal Science said the new vaccine uses a one-two-three punch to develop an immune system protection against the AIDS virus.

18.   The experimental vaccine used a bacterium called BCG, for bacillus Calmette-Guerin, that is structurally similar to the tuberculosis germ.

19.   The experimental vaccine uses a different target, one that is virtually identical across strains.

20.   The new vaccine uses only parts of the pertussis bacteria to prompt the body to become immune.