Gardasil targets four strains of human papillomavirus, commonly called HPV. Males can carry HPV and transmit it sexually to their partners.
HPV can cause genital warts and penile and anal cancer in men. Each year, about 200 out of 100,000 males are newly diagnosed with genital warts, according to background information cited by the FDA. Penile cancer and anal cancer are much rarer.
Gardasil already has FDA approval for use in females ages 9 to 26. In females, HPV can cause cervical cancer.
The FDA advisory committee ruled 7 to 0, with one abstaining vote, that Gardasil's clinical trial data support the vaccine's effectiveness at preventing genital warts in males ages 9 to 26. And in a 7 to 1 vote, the advisory committee ruled that the data show Gardasil to be safe for males in that age range.
The FDA advisory committeereviewed three studies of Gardasil that together included more than 5,000 males ages 9 to 26 in various countries including the U.S.
Participants got a total of three shots of Gardasil or a placebo spread over six months. They also got checkups and tests to check for HPV infection.
Gardasil was 89% effective in preventing genital warts. The vaccine was less effective in participants who had already been exposed to HPV.
No serious side effects were seen, according to information posted on the FDA's web site.
The most commonly reported adverse events were fever and headache. Injection site reactions were more common with Gardasil than with the placebo. Most of those reactions were mild to moderate in intensity, Gardasil's maker, the drug company Merck, states in a document posted on the FDA's web site.
Gardasil is already licensed for use in males in many countries, and there haven't been any red flags raised about the vaccine's safety in the limited number of international safety reports that have been done, FDA documents state. But the FDA says that post-marketing surveillance and studies will be "essential" if Gardasil is approved for males.
There weren't enough data to assess Gardasil for preventing other conditions, since those conditions were so rare, the FDA notes.
It's now up to the FDA to decide whether to approve Gardasil to prevent genital warts in boys and young men. The FDA often follows the recommendations of its advisory committees, but it isn't required to do so.
Gardasil is up for FDA consideration only as a way to prevent genital warts in boys -- not to prevent cancer in males or to curb transmission of the HPV virus to women.