As the measles outbreak in California and beyond continues to add new cases, new information about the safety and effectiveness of vaccines against a host of preventable illnesses mounts unabated.
Among the many infections that can be prevented by immunization is human papillomavirus (HPV), the virus that causes warts and is closely linked to the development of cervical cancer. Two vaccines have been licensed for use in the United States to prevent infection with the two HPV strains (16 and 18) that cause about 70 percent of cervical cancer cases in America, one of which also protects against two strains that cause genital warts. In Australia, where the vaccine is publicly subsidized and there is little opposition to it, rates of both genital warts and cervical abnormalities have dropped substantially since it was introduced. Sadly, vaccination rates in this country are far below theirs.
A new study has just been published that should help lay some parents’ concerns about the vaccine to rest. Because the strains of HPV linked to genital warts and cervical cancer are transmitted sexually, there has been fear among socially conservative groups that vaccinating against it would be perceived as giving license to sexual promiscuity among young people who receive it. It was sentiments like these that got Texas Gov. Rick Perry in hot water when he made the vaccine mandatory there, and put Rep. Michele Bachmann on the warpath to Crazytown.
Published in the journal JAMA Internal Medicine, the new study used insurance data to investigate whether being vaccinated against HPV led to higher rates of sexually transmitted infections (STIs) among adolescent girls. Looking through information from 2005 to 2010 about rates of several STIs, including chlamydia, gonorrhea, herpes, HIV, and syphilis, the authors found that receiving the vaccine did not make the girls any more likely to have been infected than their unvaccinated peers.
Leaving aside the questionable moral calculus of keeping girls susceptible to a preventable illness and increasing their risk of cancer as a means to disincentivize sexual activity, these data should be reassuring to some parents. This new information lends credence to an earlier study that showed no change in sexually risky behavior related to teenagers’ perceptions about the vaccine. Worries that vaccinated teens will throw caution to the wind because of it appear to be unfounded.
Parental fears such as these are among the many reasons for distressingly high rates of refusal for HPV vaccination, which also include concerns about its safety. Even in my own practice, where we do not accept patients whose parents broadly refuse to vaccinate them, generally pro-vaccine parents are uniquely leery of this one, for which we make an exception to our policy. Something about vaccinating kids against an STI before they’re sexually active, combined with the relative newness of the vaccine itself, seems to inform their hesitancy. For reluctant parents, I talk about the benefits of using preventive measures before there is risk of actual infection, and the safety and effectiveness of the vaccine. Over time, I’ve found that many change their minds and opt in.
Of course, it doesn’t help matters when vote-hungry politicians make baseless statements about vaccine safety or reputable newspapers use sloppy reporting to overstate the risk of the HPV immunization. The safety of the HPV vaccine is well established, as anyone who understands the science can tell you. The spread of misinformation keeps vaccination rates in this country well below the levels they should be, and leads to far more teenagers and young adults being at risk for preventable illnesses.
Thankfully, even with sub-optimal rates of vaccination, there has already been a substantial decline in the prevalence of the most dangerous strains of HPV. In the United States, rates have dropped in half in teenage girls since the vaccine was first introduced. Let’s hope that efforts to increase education about the benefits of immunization, alongside newer recommendations to administer the vaccine to both girls and boys, will drive those rates even lower.
As for the results of the new study, I’m not at all surprised by them. Whenever I administer it, I explain to my patients what it’s for, and the protections it both gives and doesn’t give. None of them seem to have any trouble grasping this information. Counseling about reducing the risk of sexual behavior should be part of every adolescent’s medical care, and information about the safety and benefit of the HPV vaccine is just one more piece of it.
