A weakened or inactive version of a pathogen that stimulates the body's production of antibodies which can destroy the pathogen.<ref>Wile, Dr. Jay L. ''Exploring Creation With General Science''. Anderson: Apologia Educational Ministries, Inc. | A weakened or inactive version of a pathogen that stimulates the body's production of antibodies which can destroy the pathogen.<ref>Wile, Dr. Jay L. ''Exploring Creation With General Science''. Anderson: Apologia Educational Ministries, Inc. |