The army of "Gardasil girls" featured in Merck's aggressive ad campaign may soon have new recruits in the fight to be "one less" woman with cervical cancer - boys.

And while some tenets of the debate are the same - vaccinating kids for the sexually transmitted human papapilloma virus well before they're even old enough for their first high school dance - there's a gender twist: Some see it as submitting boys to an altruistic vaccine, one they'd get to protect girls.

Now, families with both teen girls and teen boys may find themselves at an intersection of morals and mandates - where virtue meets virus.

Merck tells CNN that studies on Gardasil in boys should be completed this year, and it hopes to have the vaccine approved and available to young men as early as next year, likely for 16-to 23-year-olds - in the form of the same series of three shots that young women now receive.

It's not just a vaccine to prevent cervical cancer, Merck insists.

Merck says Gardasil is showing promise of protecting boys from genital, penile and rectal warts. Experts say among gay men, cancer of the anus is becoming almost as common as cervical cancer, and some clinics are starting to do regular HPV smears in men.

But just as approval for girls wasn't an easy road, the issue of "should or must get" is stickier with boys. After the FDA approved the vaccine last June for girls and women ages 9 to 26, the CDC immunization advisory panel later recommended all 11-and 12-year-old girls get the shots.

Some facts to consider: HPV is the leading cause of cervical cancer in women, among the top cancer-killers of women. If boys could be vaccinated, the spread of the virus would slow considerably, according to public health officials. According to the CDC, 50 percent of sexually active men and women acquire genital HPV infection at some point in their lives. Gardasil protects girls and women against four of the dozens of strains of human, or HPV, two of which are responsible for 70 percent of cervical cancer cases. The other two types account for 90 percent of genital warts, which affect both men and women.

Of course, there are other things that protect teens from HPV, including abstinence. Critics say that should be the focus, rather than pushing a vaccine on them. "Only in the past few decades have we said that it is OK and natural," writes one blogger on the issue of Gardasil for boys. "Baloney. I would teach my child fornication is wrong, and that a young man should retain his virginity until marriage."