Why vaccinate girls but not boys against HPV?

Science, technology, and life.
Oct. 15 2009 10:10 AM

Sexually Transmitted Injection

Why vaccinate girls but not boys against HPV?

A box and vial of Gardasil. Click image to expand.
Gardasil

Should boys be vaccinated against the human papillomavirus?

William Saletan William Saletan

Will Saletan writes about politics, science, technology, and other stuff for Slate. He’s the author of Bearing Right. Follow him on Twitter.

You've probably heard about girls being vaccinated everywhere for HPV. The virus has been implicated in cervical, vulvar, and vaginal cancers. But it can also cause diseases that affect men and boys: oral, anal, and throat cancers, not to mention genital warts and juvenile onset recurrent respiratory papillomatosis, an infant respiratory condition that may result from maternal HPV infection. "Recent data on the use of the HPV vaccine in males suggest high efficacy against vaccine type infections and external genital lesions," says a study published last week in the British Medical Journal.

So, should boys be vaccinated?

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No, say the authors. "Our results suggest that if vaccine coverage and efficacy are high among preadolescent girls (12 years), then including boys in an HPV vaccination programme is unlikely to provide good value for resources compared with vaccinating girls only. … [O]ur analysis favours HPV vaccination of preadolescent girls (with continued screening in adulthood) as a valuable intervention for its cost. … Including boys in the vaccination programme, however, generally exceeded conventional thresholds of good value for money."

Why vaccinate girls but not boys? The authors cite several factors. First, HPV is more likely to harm girls. Second, the vaccine is more effective in girls. Third, the rate of viral transmission depends on the virus's prevalence "in the opposite sex at any given time." If girls are routinely vaccinated, there's nothing for boys to catch or transmit.

In other words, boys don't have to get vaccinated for the same reason they don't have to wash dishes, do laundry, buy birth control, or think about other people in general: Girls will do it for them.

Why do HPV vaccines work better in girls than in boys? Because they were designed for and tested in girls. It's true that HPV affects girls more than boys, but the same can be said of pregnancy. There's still a male in the equation somewhere. Boys certainly share the pleasure. Why not share the responsibility? And what about that infant respiratory condition? Shouldn't men do their part to prevent it?

If you want to see a world where men wash dishes and do laundry, it isn't hard to find. It's a world where men live, have sex, and share household responsibilities with other men. They don't have wives or girlfriends to think about and take care of everything for them. They have to do it themselves.

The same is true of protection from sexually transmitted viruses. The authors of the BMJ paper concede that they "only represented heterosexual partnerships and therefore did not reflect HPV transmission among men who have sex with men, who face a high risk of anal cancer and may realise a greater benefit from HPV vaccination." But the argument for vaccinating gay men isn't just that they might benefit. It's that vaccinating women won't help them. They can't count on somebody else to take care of the problem.

What would happen to straight men if women weren't vaccinated? The authors played out that scenario in their mathematical models. "If coverage in girls ends up being low, then vaccinating boys became much more attractive," the lead author concedes.

Maybe routine vaccination of both sexes is overkill. But in that case, perhaps we should ask why the partner who takes care of the birth control should get the vaccination, too.

(Now playing at the Human Nature blog: 1) Polanski and airing ugly truths. 2) Polanski and pedophilia. 3) The beauty of artificial virginity.)