CHICAGO (CNNMoney.com) -- GlaxoSmithKline said Tuesday its experimental Cervarix vaccine can protect a wide age-range of girls and women against cervical cancer, but analysts wonder if that's enough to give it a leg up on Merck's Gardasil.
U.K.-based Glaxo unveiled a late-stage study showing that Cervarix protects girls and women, ages 9 to 55, against human papillomavirus, the sexually transmitted virus that causes cervical cancer.
The 18-month study, which was announced at the annual conference of the American Society of Clinical Oncology, showed the vaccine is 100 percent effective against the two most common strains of the virus.
U.S.-based Merck already has a cervical cancer vaccine on the market called Gardasil. Gardasil is approved by the Food and Drug Administration to protect girls and woman between a narrower age range of 9 to 26.
Merck launched Gardasil in 2006, and many analysts have hailed the product as a potential multi-billion dollar blockbuster. In its first six months on the market, sales totaled $235 million. Analyst projections for Gardasil peak sales range as high as $4 billion a year.
But Gardasil could soon face competition - assuming that Cervarix gets FDA approval. The question is, How much?
Gardasil has an edge, analysts say, because it made it to the market first. It's also unclear just how much of a toehold Cervarix would gain from the wider age group, because the vaccine is considered most effective when administered to girls before they become sexually active. Even in young women, HPV is common, though only the most severe strains cause cervical cancer.
"The broader the label, the broader the market," said Miller Tabak analyst Les Funtleyder, who projects peak annual Gardasil sales of $2 billion by 2010. "But is it enough to be a game changer in the market? It's unlikely, but not impossible, to give [Glaxo] a big edge."
Brian Lortie, vice president of worldwide development for HPV vaccines for Glaxo, said that vaccinating "the younger girls before their sexual debut is very critical."
But he added that older women "still have a high chance of infection, even if they've already been infected. [The new study results] speak very nicely to the power of the product."
Glaxo filed Cervarix, along with data from its newly-released study, with the FDA in March. This is an 18-month study; Glaxo previously announced study results for one year. 
