A committee that advises the Centers for Disease Control and Prevention is set to decide today whether to recommend routinely vaccinating boys and young men against sexually transmitted forms of human papillomavirus, the cause of most cervical and anal cancers as well as most mouth and throat cancers.
A "yes" vote would send the issue on to the CDC director and secretary of the U.S. Department of Health and Human Services for final approval.
The CDC already recommends routinely immunizing girls with a three-dose vaccine beginning at age 11 or 12, before they become sexually active, although they can be vaccinated as young as age 9. The agency issued a so-called permissive recommendation giving males from ages 9 through 26 the option of receiving the vaccine.
As it takes up the issue of vaccinating boys during today's meeting in Atlanta, the CDC's Advisory Committee on Immunization is also expected to determine the age at which routine vaccinations should begin. Because cost-effectiveness drops with age, the panel must decide whether to close the window of opportunity for catch-up vaccines at either age 21 or age 26.
The prospect of requiring that preteen boys and girls get vaccinated against a sexually transmitted infection has drawn the sharpest outcry from some parents, who fear that vaccinating preteens might encourage promiscuous behavior. Vaccination policies also have become an issue in the 2012 presidential campaign, with several GOP candidates objecting to mandates for HPV vaccination.
Many infectious disease specialists welcome universal vaccination as a key tool in reducing the toll of preventable diseases.
"Vaccination is perhaps the greatest invention of medicine," said Dr. John Sinnott, director of the Division of Infectious Disease at the University of South Florida. "It is a tragedy that this vaccine has become politicized."
But Dr. Lawrence Stanberry, chief pediatrician at New York Presbyterian Morgan Stanley Children's Hospital, said parents support universal recommendations more recommendations targeting groups at higher risk.
"Recommending universal immunization for girls and making the recommendation for boys permissive sends parents mixed messages," Stanberry said. He offered a fairness argument for recommending vaccinations for both sexes. "Girls acquire the infection from boys and it seems appropriate, even fair, for boys to share responsibility for maximizing community [herd] immunity," he said.
Nearly a dozen experts contacted by ABC News cited "herd protection" from HPV-associated diseases in both women and men as a main reason they supported universal immunization.
William Muraskin, an urban studies professor at Queens College in New York, said it's hard to determine which men and women will benefit directly from vaccination. "The HPV vaccine if given before males become sexually active will also protect those who will become homosexual or bisexual," Muraskin said. Routine vaccination of all young men protects "an important subgroup that otherwise will be at significant risk but cannot be identified until it is too late."
The panel is expected to issue a policy statement on the importance of vaccinating men who have sex with men, because of the risk they could develop anal cancer from HPV.
Two HPV Vaccines On The Market Protect Against Multiple Strains
There are two HPV vaccines currently available, both of which protect against the two principal cancer-causing types of HPV, HPV 16 and HPV 18. By CDC estimates, the two strains cause 15,000 malignancies in women and 7,000 in men every year. The two strains account for an estimated 70 percent of cervical cancers, about 70 percent of vaginal cancers and most vulvar cancers. HPV 16 by itself causes 85 percent of anal cancers.
In addition to protecting against HPV 16 and HPV 18, Merck's Gardasil protects against two other disease-causing strains, HPV 6 and HPV 11, responsible for 90 percent of genital warts as well as cervical cell changes. GlaxoSmithKline's Cervarix protects against HPV 16 and HPV 18, but also has been found to confer some protection against three other cancer-causing strains, HPV 31, HPV 33 and HPV 45.
Dr. Diane Harper, director of the Gynecologic Cancer Prevention Research Group at the University of Missouri-Kansas City called it "misguided to think that all boys will gain any health benefit from HPV vaccination." She contended that "mass vaccination for the prevention of the other HPV-associated cancers puts large numbers of people at risk for harms from vaccination compared to both the personal and public health risk of anal, penile, and oropharyngeal cancers."
In a background memo leading up to the vote, the CDC estimated that routinely vaccinating 11- and 12-year-old boys would likely be cost-effective. If 1 million 12-year-old boys were vaccinated, over the course of a lifetime, they would prevent 2,381 cases of mouth and throat cancer; 633 cases of anal cancer and 169 cases of penile cancer, assuming the vaccine was 75 percent effective against those conditions.
ABC News' Brian Hartman and Lara Salahi contributed to this story.