An influential federal advisory group on Thursday endorsed a

Merck

(MRK) - Get Report

vaccine that fights the virus that causes cervical cancer, saying it should be added to a routine list of shots for girls as young as 11 and 12.

The panel said the vaccine, Gardasil, could be offered for 9- and 10-year olds at a doctor's discretion, and it recommended that it be given to those between ages 13 and 26 who had not been previously vaccinated.

The advisory group also said Gardasil should be included in a federal program that pays for vaccines for poor children.

"This is a great opportunity to make advances in prevention," said Anne Schuchat, director of the National Center for Immunization at the federal Centers for Disease Control and Prevention.

The panel's votes were unanimous for Gardasil, the first vaccine against human papillomavirus, or HPV. Gardasil protects against two types of HPV that account for 70% of cervical cancer cases in the U.S. and two types of HPV that are linked to 90% of genital warts.

Support by the panel of experts, the Advisory Committee for Immunization Practices, provides an important booster shot for Merck. Some analysts say Gardasil could produce as much as $3 billion a year in peak-year sales depending on the degree of acceptance in U.S. and foreign markets. Merck's stock closed up 79 cents, or 2.3%, to $35.89.

Although the Food and Drug Administration

approved Gardasil earlier this month for girls as young as 9 and women as old as 26, the vaccine needed a strong endorsement from the vaccine-practices advisory committee which advises the Centers for Disease Control and Prevention.

Merck, the FDA and public health experts say it's best to administer Gardasil before girls become they become sexually active. The vaccine doesn't work against other HPV strains. Although the vaccine-advisory panel said Gardasil should be given before they become sexually active, it also said "females who are sexually active should still be vaccinated."

Despite tests showing Gardasil's effectiveness, Schuchat said the vaccine "will not replace other prevention strategies, such as cervical cancer screening for women or protective sexual behaviors. Women should continue to get pap tests as a safeguard against cervical cancer."

The panel's recommendations provide scientific and financial clout because they strongly influence insurers; medical societies, such as the American Academy of Pediatrics; and public health agencies, as well as state legislatures that provide financing for vaccines. The states will determine if Gardasil must be mandatory for school-age children.

The advisory committee recommended that Gardasil be included in the federal Vaccines For Children program, which provides free vaccines to people under 19 who are uninsured, Medicaid-eligible, Native American or natives of Alaska. The panel's suggestions will be sent to the Centers for Disease Control and Prevention and the Department of Health and Human Services, which will issue final recommendations in a few months.

Gardasil costs $120 a shot for a regimen of three shots that must be given within six months. It is unclear what discounts Merck might offer to insurers or government-aid programs, although CDC's Schuchat said the price for Gardasil under the Vaccines For Children program would be subject to negotiation.

Last month, Merck said it would create a new vaccine-aid program for adults who are uninsured or underinsured, providing free vaccines, including Gardasil, starting next month. "Merck will continue to provide its pediatric vaccines at significantly discounted prices for use in government-funded programs that provide free vaccines to uninsured children and to other children with limited access to vaccines," the company said.

Merck licenses Gardasil from Australia's

CSL Ltd

.

On average, the CDC says there are 9,710 new cases and 3,700 deaths from cervical cancer in the U.S each year. HPV is the most common sexually transmitted infection in the U.S., and more than 20 million men and women have HPV. The virus is most common in young women and men who are in their late teens and early 20s, the CDC says. By age 50, at least 80% of women will have acquired an HPV infection, according to the CDC.