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The HPV vaccine works. So why aren't more girls getting inoculated?

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While parents who eschew MMR out of fears of autism might be the most frequently discussed "anti-vaxxers," they’re not the only ones who are letting misinformation dictate choices about their children’s health. In fact, far more parents are neglecting to immunize their children with Gardasil, a cancer vaccine.

Gardasil provides immunity against several strains of HPV, a virus known to be responsible for numerous forms of cancer — most notably cervical and anal — and genital warts. The vaccine is incredibly effective: in its original form, it protects against the four strains of HPV that cause 70 percent of cervical cancer cases and 90 percent of genital warts; an updated version approved this past December protects against five additional strains, potentially eliminating 90 percent of cervical, vulvar, vaginal, and anal cancers. When given before first sexual contact, Gardasil can offer near full protection against the most common sexually transmitted infection (STI), as well as the life-threatening cancers that sometimes result from it.

only 38 percent of adolescent girls had received all three doses of the vaccine

But nearly a decade after its introduction to market, rates of Gardasil inoculation are still low. As recently as 2013, only 38 percent of adolescent girls ages 13–17 (the primary target group for inoculation) had received all three doses of the vaccine in the US — about half the rate seen in other developed countries, like Australia. There are several reasons for this lag in vaccination rates. As with any vaccine, there’s a small number of people who refuse Gardasil out of a general stance against vaccination. But that’s not why most people avoid Gardasil. These people are both parents who fear that inoculating children against an STI will encourage reckless and promiscuous behavior and, more surprisingly, are educated parents who consider themselves pro-sex and pro-vaccine, but simply aren’t convinced that Gardasil itself is safe, especially for children.

gardasil

(Eugene Peretz)

Though much has been made of Gardasil’s status as sex-related vaccine, a study recently published in JAMA Internal Medicine indicates that fears of Gardasil-induced promiscuity are likely misguided. An investigation of insurance claims from over 200,000 teenage girls (about 10 percent of whom had received Gardasil) showed no indication that vaccination made girls more likely to engage in risky sexual behavior.

there's no indication that a simple vaccine acts as a catalyst for sexual behaviorThe idea that a vaccine like Gardasil might promote unsafe behavior isn’t entirely baseless. One study found a correlation between STI-related treatments (in this case, HIV therapies) and an increase in risky sexual behaviors, says Anupam Jena, an author of the more recent study on Gardasil. But, Jena points out, there’s a vast difference between HIV-infected adults (many of whom have a history of engaging in risky sex- or drug-related behavior) and adolescent girls. In the case of teenage girls, there’s no indication that a simple vaccine acts as a catalyst for sexual behavior, risky or otherwise.

At most, Jena’s study indicated that girls who are already engaging in risky sexual behavior are more likely to get vaccinated with Gardasil. That's important for understanding the study's outcome. Girls who received the vaccine did have higher infection rates after inoculation, but they also had higher rates of STIs before they ever got the shot. Once researchers controlled for that factor, the differences between the vaccine and control groups vanished. To the extent that there’s any correlation between vaccination and promiscuity, it’s a heartening one: girls who might need the vaccine most are seeking it out.

adverse reactions are real, but they're also rareBut the mythical connection between Gardasil and risky sexual behavior is only one part of the misinformation that plagues the shot; just as pernicious are rumors about its safety. One frequently cited (and debunked) anecdote blames Gardasil for the death of 32 women. Some cite negative experiences that friends, family, and loved ones have had with the vaccine as a reason to steer clear. "I got the shot, stood up, walked into Planned Parenthood’s lobby to pay, and passed out, but with seizure-like symptoms. I apparently was moaning and moving around, though totally unconscious," AC Shilton told The Verge of her own experience with Gardasil. "It’s a total mystery as to what happened. I had never had a vaccine reaction before, have no known medical allergies and am generally a really healthy person." While adverse experiences like Shilton’s are real, they’re also rather rare – as Matthew Herper notes in Forbes, the MMR vaccine has received more than double the number of adverse effect reports as Gardasil.

hpv infection chart

Prevalence of high-risk and low-risk types of HPV among women 14 to 59, 2003 through 2006. (Hariri S, Unger ER, Sternberg M, Dunne EF, Swan D, Patel S, et al)

These fears, on examination, seem to come from a more general anxiety about science, medicine, and the effects of new technology. In talking to people with hesitations about Gardasil, I repeatedly heard refrains about how new and unproven the vaccine is. Parents cited the relatively recent release of the vaccine, ignoring the fact that Gardasil’s human trials were over a decade ago — and that, aside from the virus itself, there’s very little that's actually new or innovative about Gardasil at all, says Greg Moe, a scientist working with the Children’s Hospital Oakland Research Institute.

Almost all the vaccine’s ingredients "could be found in a typical vitamin pill."Though some parents cite scary-sounding ingredients that make up Gardasil as a reason to hesitate, virtually everything found in Gardasil (including intimidating sounding items like polysorbate 80 and sodium borate) can be found in many common food products, pharmaceuticals, and even the human body. Almost all the vaccine’s ingredients "could be found in a typical vitamin pill," Moe says. Furthermore, the science behind Gardasil isn’t particularly new: the adjuvant used to increase immune response (and create immunity), has been used for over 50 years in vaccines safely given to hundreds of millions of people; similarly, yeast-based vaccines like Gardasil have been used for decades with no ill effect.

Given Gardasil’s safety and efficacy, only one real question remains: is wide-scale inoculation actually necessary from a public health perspective? In 2011, NPR reported that Diane Harper, a professor at the University of Missouri-Kansas City School of Medicine who worked on studies that led to Gardasil’s approval, had expressed reservations about mandatory Gardasil inoculation among youth. Harper had no concerns about the vaccine’s safety or efficacy; she merely felt Gardasil inoculation wasn’t as imperative as marketing campaigns might suggest. Even without Gardasil, Pap smears have been proven highly effective at detecting cervical cancer cells while they’re in a pre-cancerous, and very treatable, stage. Similarly, genital warts — though unsightly and embarrassing — are highly treatable and rarely fatal. For these health concerns, Gardasil is less a major breakthrough than an improved solution for a problem we’d already more or less solved.

hpv

On the left, a normal cell from a Pap smear. On the right, an HPV-infected cell. (Ed Uthman)

But cervical cancer and genital warts aren’t the only threat posed by HPV: over the past decade, the virus has been implicated in throat and anal cancer, neither of which are as easily detected and prevented as cervical cancer.  And though Gardasil isn’t the only way of preventing cervical cancer, it’s far more pleasant than undergoing a colposcopy and removal of part of the cervix. Given the option, why wouldn’t we want to spare adolescents the pain, suffering, and expense of having to deal with HPV?

parents only have a limited amount of control over their children's sexual decisions Perhaps, it comes back to the fact that Gardasil is associated with sex, and for some parents, acknowledging their children’s potential future sex lives feels a bit too much like ceding control over their children’s most intimate decisions. "Children as young as nine are urged to begin the series, with the assumption that they will be sexually active soon thereafter," says Erica Sandberg, a generally pro-vaccine parent — with the exception of Gardasil. "I find that horrible. Will some? Unfortunately, yes. But I’ve been highly involved with my daughter’s education regarding these matters since she could speak and… I’m secure that she’ll make smart decisions."

The anxiety is understandable. But it stems from this unavoidable fact: parents only have a limited amount of control over their children’s sexual decisions. However smart those decisions are, HPV — which can be transmitted even when condoms are used — is still a very real risk. In fact, it’s the most commonly transmitted STI tracked by the US Centers for Disease Control and Prevention, one with potentially fatal consequences.

"Here is a therapy we have to prevent cancer, and we’re not using it," says Jena — something that would be unthinkable were we discussing a vaccination for colon or skin cancer. Hopefully, with continued awareness and education, we’ll be able to reverse that course.