The US Food and Drug Administration has approved Merck & Co’s Gardasil, the first vaccine against the human papillomavirus that causes cervical cancer and genital warts, shortly after the product got its first green light in Mexico.

The agency gave the go-ahead for the vaccine in girls aged between 9 and 26 on the back of data that showed Gardasil was effective in preventing infection with two strains of HPV that cause 70% of cervical cancer cases, and two responsible for 90% of genital warts. It has also been cleared to prevent vulvar and vaginal cancers.

If approved, Gardasil has been tipped to become a $3 billion product, with a rival product from GlaxoSmithKline called Cervarix, not yet submitted for approval in the USA, expected to reach $2 billion in peak sales. Gardasil should be launched onto the US market before the end of the month, said Merck.

However, the ultimate sales potential of Gardasil will depend on recommendations due to be delivered by the Centers for Disease Control on June 29, that will establish how the vaccine will be incorporated into routine immunisation schedules.

The vaccines have already courted controversy with some groups initially claiming that immunising young girls against HPV - a sexually-transmitted infection - could be taken as an encouragement to become sexually active. But resistance seems to have receded as the clear health benefits of vaccination have emerged.

There is debate about the safety of giving Gardasil to women who have already been infected with HPV as there is a possibility that it may increase the risk of premalignant lesions.

Nearly 300,000 women around the world die each year as a result of cervical cancer, and Merck says Gardasil could save the lives of nearly 200,000 of them, although with a US price tag of $120 per dose – and three doses required over six months to provide protection - the vaccine could prove too expensive for some countries. However, Merck said it is looking at ways to make Gardasil available to poorer countries through subsidised programmes.

Gardasil has also been submitted for approval in the European Union and most other regions around the world.