HPV Shot Prevents Genital Warts in Boys and Men

Study Adds to Debate Over Vaccination of Males for Prevention of HPV Infection

By Denise Mann
WebMD Health News

Reviewed by Laura J. Martin, MD

Feb. 2, 2011 -- The human papillomavirus (HPV) vaccine can help stave off genital warts in boys and men, according to a new study in the Feb. 3 issue of the New England Journal of Medicine.

Of 4,065 boys and men aged 16 to 26 from 18 countries, vaccination with an HPV vaccine that targets four types of HPV infection -- HPV-6, HPV-11, HPV-16, and HPV-18 -- protects against infection with these types of HPV and potentially the development of related external genital warts or lesions.

HPV, a sexually transmitted disease, can be transmitted through vaginal, anal, and oral sex and has been linked to genital warts as well as cervical, vaginal, vulvar, oral, penile, and anal cancers.

Two HPV vaccines are now approved by the FDA: Cervarix and Gardasil. Both of these vaccines are recommended to prevent cervical cancers. These vaccines are now on the CDC's routine childhood vaccine schedule for girls starting at age 9.

The Gardasil vaccine has also received FDA approval for prevention of genital warts. The vaccine is recommended for optional use in boys and men. The vaccine is used in girls and boys and young adults ages 9 to 26 for prevention of genital warts caused by HPV types 6 and 11.

"The most salient message is that the [Gardasil] vaccine can prevent HPV infection on the external genital region, which means that we can now prevent most cases of genital warts if the boy is vaccinated at a sufficiently early age," says study researcher Joel Palefsky, MD, a professor of medicine at the University of California, San Francisco.

HPV Vaccine for Males

The new study does not address cancer risk in boys and men, he says. "These data provide evidence that the vaccine can be efficacious in males, and adds to the list of reasons to consider vaccinating boys and men," he says. "In theory, this could cut down on cancers, but it hasn't yet been proven."

The big debate now is whether or not universal vaccination of young men should be encouraged, he says.

"HPV is a sexually transmitted infection, and the burden of vaccination should not fall solely on girls and women. HPV causes disease in men too," he says.

In addition, men who have sex with men are at increased risk for genital warts and anal cancer and likely would not benefit from female vaccination, he says.

Casting a wide net that vaccinates all boys aged 9-26 would cover such high-risk groups, he says.

So why not do it?

"The main disadvantage is cost, because thus far the vaccine appears to be safe," he says. "It's less cost-effective because most of the serious diseases such as cervical cancer occur in women, not men."

"Theoretically, if you vaccinated all women, you wouldn't need to vaccinate men except for men who have sex with other men," he says. Not every female who is eligible for the vaccine has received it, and many females -- and their current or future sexual partners -- remain unprotected.

Jane J Kim, PhD, an assistant professor of health decision science in the department of health policy and management at the Harvard School of Public Health in Boston, wrote an editorial that accompanied the new study.

"It's telling us something quite promising. The [Gardasil] shot has strong potential to reduce genital wart cases in boys with high effectiveness," she writes.

"More recent data that has resulted in the FDA expanding the use for prevention of anal lesions in women and men has resurfaced the debate about routine vaccination for everyone," she writes.

"It's going to be hard to target the boy who will grow up to be highest risk for anal cancer of anyone in the country -- men who have sex with men," she says. "Our ability to target these males when they are really young and the vaccine is most beneficial is a hard sell and not feasible as people don't necessarily become aware of their sexual orientation that early."

With universal vaccination, this issue goes away, she says. "You wouldn't have to think about it and you prevent HPV in everyone."

Vaccines: Boys vs. Girls

But there is more to this discussion.

"The most cost-effective use of vaccine, as we know it today, is to vaccinate young girls before they get exposed to HPV," she says. "Men who have sex with men would also benefit greatly, and the rest of the population of men would benefit in terms of reducing genital warts, possible anal lesions as well as anal and penile cancer, but they are at low risk for those cancers."

"There is benefit, but are we willing to spend that much money on a vaccine to get that amount of benefit," she says. "Most of the evidence suggests that it would not be a good use of health dollars to vaccinate all boys."

This could all change if the vaccine cost comes down or if the uptake in young females remains low, she says. "It is trending upward, but if it remains low and we can cover boys instead, that may be a good cost-effective strategy."

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SOURCES: Joel Palefsky, MD, professor of medicine, University of California, San Francisco.Jane J Kim, PhD, assistant professor, Harvard School of Public Health, Boston.Giuliamo, A.R., New England Journal of Medicine, 2011; vol 364: pp 401-411.Kim, J.J. New England Journal of Medicine, 2011; vol 364: pp 393-395.

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