A new vaccine that protects against cervical cancer has set up a clash between health advocates who want to use the shots aggressively to prevent thousands of malignancies and social conservatives who say immunizing teen-agers could encourage sexual activity.

Although the vaccine will not become available until next year at the earliest, activists on both sides have begun maneuvering to influence how widely the immunizations will be employed.

Groups working to reduce the toll of the cancer are eagerly awaiting the vaccine and want it to become part of the standard roster of shots that children, especially girls, receive just before puberty.

Because the vaccine protects against a sexually transmitted virus, many conservatives oppose making it mandatory, citing fears that it could send a subtle message condoning sexual activity before marriage. Several leading groups that promote abstinence are meeting this week to formulate official policies on the vaccine.

Officials from the companies developing the shots - Merck & Co. and GlaxoSmithKline - have been meeting with advocacy groups to try to assuage their concerns.

"What the Bush administration has done has taken this coterie of people and put them into very influential positions in Washington," said James A. Morone Jr., a professor of political science at Brown University. "And it's having an effect in debates like this."

The vaccine protects women against strains of a ubiquitous germ called the human papilloma virus. Although many strains of the virus are innocuous, some can cause cancerous lesions on the cervix (the outer end of the uterus), making them the primary cause of this cancer in the United States. Cervical cancer strikes more than 10,000 U.S. women each year, killing more than 3,700.

The vaccine appears to be virtually 100 percent effective against two of the most common cancer-causing HPV strains. Merck, whose vaccine is further along, plans to ask the Food and Drug Administration by the end of the year for approval to sell the shots.

Exactly how the vaccine is used will be largely determined by the Advisory Committee on Immunization Practices (ACIP), a panel of experts assembled by the Centers for Disease Control and Prevention in Atlanta. The panel issues widely followed guidelines, including recommendations for childhood vaccines that become the basis for vaccination requirements set by public schools.

Officials of both companies noted that research indicates the best age to vaccinate would be just before puberty to make sure children are protected before they become sexually active. The vaccine would probably be targeted primarily at girls but could also be used on boys to limit the spread of the virus.

"If you really want to have cervical cancer rates fall as much as possible as quickly as possible, then you want as many people to get vaccinated as possible," said Mark Feinberg, Merck's vice president of medical affairs and policy, noting "school mandates have been one of the most effective ways to increase immunization rates."

"I would like to see it that if you don't have your HPV vaccine, you can't start high school," said Juan Carlos Felix of the University of Southern California in Los Angeles, who leads the National Cervical Cancer Coalition's medical advisory panel.

At the ACIP meeting last week, panel members heard presentations about the pros and cons of vaccinating girls at various ages. A survey of 294 pediatricians presented at the meeting found that more than half were worried that parents of female patients might refuse the vaccine, and 11 percent of the doctors said they thought vaccinating against a sexually transmitted disease "may encourage risky sexual behavior in my adolescent patients."

"Some people have raised the issue of whether this vaccine may be sending an overall message to teen-agers that, 'We expect you to be sexually active,' " said Reginald Finger, a doctor trained in public health who served as a medical analyst for Focus on the Family before being appointed to the ACIP in 2003, in a telephone interview.

"There are people who sense that it could cause people to feel like sexual behaviors are safer if they are vaccinated and may lead to more sexual behavior because they feel safe," said Finger, emphasizing he does not endorse that position and is withholding judgment until the issue comes before the vaccine policy panel for a formal recommendation.

"I've talked to some who have said, 'This is going to sabotage our abstinence message,' " said Gene Rudd, associate executive director of the Christian Medical and Dental Associations. But Rudd said most people change their minds once they learn more, adding he would probably want his children immunized. Rudd, however, draws the line at making the vaccine mandatory.

"Parents should have the choice. There are those who would say, 'We can provide a better, healthier alternative than the vaccine, and that is to teach abstinence,' " Rudd said.

In a statement, the conservative Family Research Council said, "While we welcome medical advances such as an HPV vaccine, it remains clear that practicing abstinence until marriage and fidelity within marriage is the single best way of preventing the full range of sexually transmitted diseases."

The council plans to meet Wednesday to discuss the issue. On the same day, the Medical Institute for Sexual Health in Austin, Texas, which advises conservative groups on sexuality and health issues, is convening a one-day meeting to develop a position statement.

"It is not our intention in any way, shape or form to promote our vaccine as a substitute for any other prevention approach, be it abstinence or screening," Merck's Feinberg said.

"We hope when people understand more about what the disease is and how it can be prevented that their concerns will have been allayed," Feinberg said.

This is cache, read story here