Both Merck's (nyse: MRK - news - people ) Gardasil, which is already on the market, and Glaxo's (nyse: GSK - news - people ) Cervarix, which is not, work by preventing infection of strains of the human papilloma virus (HPV) that, in turn, cause the vast majority of cervical cancer cases.
FORBES: Glaxo Goes Head-To-Head With Merck