GlaxoSmithKline's rival has criticised as inferior its new cervical cancer vaccine Cervarix in an attempt to shore up an early lead in its competitor product.

Sanofi Pasteur MSD has been wooing investors this week with presentations claiming greater proved health benefits from Gar-dasil, which was developed by Merck of the US, in preventing human papilloma virus infections, the leading cause of cervical cancer.