On their next visit to the pediatrician, parents of adolescent boys may be asked if they want their sons to get an expensive vaccine they've never before considered—the HPV shot.
Recently approved for boys, the three-dose immunization has been given to girls to prevent cervical cancer, often caused by the sexually transmitted human papillomavirus.
Many parents of girls still are not convinced their daughters should get the vaccine, despite new scientific evidence of its safety. For boys, there are even more questions.
What is known: Getting your son vaccinated will protect him against genital warts. A Moffitt Cancer Center researcher studying the vaccine is among scientists who are learning that it may also reduce boys' risk of certain cancers. And the vaccine could protect a boy's future sexual partners from HPV infections.
But leading national experts don't have strong recommendations for boys. They are focused on encouraging girls to get the vaccine, which is known to protect against cervical cancer.
Linda Watson of St. Petersburg, Florida, is a pediatric nurse, but like many parents, she hadn't heard about the vaccine's availability to boys until recently. But she was open to getting it for her 12-year-old son, after learning more and talking to her pediatrician.
"With something like HPV, you can vaccinate a large number of the girls, but then if boys aren't vaccinated, they are still getting it," she said. "The more people are vaccinated, the more you eradicate."
And while she would like to think vaccinating her son against HPV would benefit his future wife, she noted that parents need to be realistic about their children having premarital sex.
"To be blind is not really the way to go about it," she said. "You need to really consider how you are protecting your children."
One of the two FDA-approved HPV vaccines, Gardasil, is given to both girls and boys. It protects against four types of HPV, the most common sexually transmitted infection.
Experts at the Centers for Disease Control and Prevention recommend girls get vaccinated between age 11 and 12, ideally before they become sexually active. Immunizations can start as young as 9, and can be given through 26.
Late last year, Gardasil was approved for boys of similar ages to protect against genital warts. The CDC's immunization experts said boys may get the vaccine, but stopped short of saying they should, as they have for girls.
The American Academy of Pediatrics hasn't taken an official position, but is expected to soon issue similar guidance.
"It would be much more cost-effective if we immunized all girls to prevent HPV-related disease than if we also focused on immunizing boys," said Dr. Joseph Bocchini, chairman of the AAP's committee on infectious diseases, the panel studying the issue.
Gardasil carries a sticker price of $130 per dose, or roughly $400 for the series. (Insurance covers much of the cost for girls, but coverage for boys may be spotty.)
For girls, the cost is balanced against the 11,000 new cases of cervical cancer each year in the United States. The disease kills 4,000 women a year. Gardasil and the other vaccine, Cervarix, are effective against the HPV types that cause most cervical cancers.
In boys, Gardasil protects against genital warts. So from a public health perspective, Bocchini noted it's a better use of resources to guard women against the potentially fatal and more costly disease.
But he said getting boys vaccinated would slow the spread of the virus. Since only 18 percent of girls have received all three shots, according to the latest CDC data, boys could help to protect girls.
"The models show us that the fewer girls that are immunized, the more cost-effective it is to give the vaccine to boys, because then you could prevent infection in girls by giving the vaccine to boys," said Bocchini, chair of the department of pediatrics at Louisiana State University Health Sciences Center in Shreveport.
Nearly all cervical cancers are caused by HPV. But the virus can also play a role in other cancers that are less common, including anal, vaginal, vulvar, penile, and some neck and head cancers.
Researchers are learning about the vaccine's potential to prevent HPV-related cancers in men. And much still is unknown about HPV.
Most people who are infected with HPV have no symptoms, and infections usually clear up without treatment. But in some, health problems from HPV may persist for years.
As lead investigator for Gardasil's trials in males, Moffitt chair of cancer epidemiology Anna Giuliano is finding the vaccine could guard against anal cancer in men.
Giuliano's latest research, from studies funded by vaccine-maker Merck, has not yet been published, a step that typically comes with additional vetting.
But as the mother of a 11-year-old boy, she thinks equity for males is at stake, too.
"I feel like it's my responsibility to help make sure that my son doesn't get an infection, and that he doesn't pass that infection to some nice young girl," she said. "I also feel like he should have the right to benefit from the vaccine like the girls in his class do."
Half of sexually active adolescents become infected with at least one type of HPV within two years of their first sexual experience, noted AAP's Bocchini .
Some parents think the HPV vaccine is too new to trust, but fresh data from the final stage of clinical trials in girls shows a strong record of the vaccine's safety and effectiveness.
What is HPV?
Human papillomavirus is a viral infection. Of the more than 100 types of HPV, more than 30 types can be spread through sexual contact. Most HPV infections occur without any symptoms and go away on their own, but others can cause genital warts and some cancers. There is no cure for HPV.