The battle between two drug giants over the cervical cancer vaccine market is heating up.
A study being published in the British medical journal, "The Lancet," says GlaxoSmithKline's shot called "Cervarix" may be different from Merck's Gardasil.
The first sneak peak at the results of a large, late-stage clinical trial show Glaxo's vaccine is 90% effective at preventing the two leading pre-cancerous strains of sexually-transmitted HPV. And the researchers say it may also work on two other cancer-causing strains.
Merck's Gardasil is approved for two HPV strains that cause cancer and two that lead to genital warts.
Glaxo recently filed for FDA approval of Cervarix.
Despite the controversy over the shots, analysts expect both vaccines to become blockbuster products.
A "Lancet" editorial also urges the drug companies to make the expensive shots widely accessible in developing countries where cervical cancer is much more prevalent.