The Human Papilloma Virus, or HPV, is the most common sexually transmitted disease. At any giving time a whopping 40 percent of women are infected with one of the HPV strains. Persistent infections can lead to cervical cancer as well as other types of cancer. In 2006 immunization experts recommended that all girls, starting as young as 11 years old, receive the vaccine so that immunity had time to develop before they became sexually active.
Over the last six years religious groups and conservatives have argued against this vaccine with the point that it will lead young girls to become promiscuous.
Recently scientists from Emory University and Kaiser Permanente completed a very large study published in the journal Pediatrics, that provides substantial evidence against such an argument.
SmartPlanet caught up with Robert Bednarczyk, an epidemiologist at Emory University’s Hubert Department of Global Health, and the study’s lead author.
SmartPlanet: What is HPV and why we should care so much about it?
Bob Bednarczyk: Well, the Human Papilloma Virus is actually a family of viruses. There’s over a hundred different strains of HPV. Some strains can lead to the development of genital warts. And some strains can lead to the development of cancer in the area that the virus is infecting. Now there’s some evidence that there may be associations between HPV and cancers of the oral cavity as well.
Are genital warts a more common result than cancer?
The instances of new cases of genital warts is about one percent per year. So that tends to be higher than what we see with the anal-genital tract cancers. Typically we see maybe about 9,000 to 10,000 new cases of cervical cancer a year. The warts are a little more common.
Forty percent of women are infected with HPV at any given time. I don’t think people realize how prevalent it actually is.
Right, it's a very common virus, but luckily it can be cleared pretty readily.
So is there a real need to worry about it?
Well the issue is what happens when it isn’t cleared. And in this country we have a lot of routine pap smear screenings so we can catch some of these cancers. But you still have about 10,000 new cases of cervical cancer a year and about 3,000 deaths due to cervical cancer every year in the U.S. The HPV vaccine is a step toward helping us prevent these cases of cancer.
Why is there a debate about this vaccine?
There is an underlying concern of: Why are you vaccinating an 11 to 12-year-old? Why are you vaccinating a pre-teen against a sexually transmitted infection? So it goes more to that idea of if someone isn’t sexually active then why would you protect them against a sexually transmitted infection.
So why would you?
The vaccine works the best when it’s given exposure before the virus infects the body.
Another argument against vaccination, coming from religious groups and social conservatives, is that it might encourage promiscuity among pre-teens and teens. You recently completed a very large study that provides some of the best evidence that knocks out this argument.
There have been numerous surveys done of young women that have asked them, "If you receive this vaccine will it lead to a change in your behavior?"
What we sought to do was to move away from these surveys where you’re directly asking girls because we know that questions about sexual activity can be difficult to answer. There may be biases involved in their responses.
So we looked at outside markers that could be associated with sexual activity. And within the Kaiser Permanente system we were able to use our research databases and identify outcomes that would be related to sexual activity.
Testing or diagnosis for pregnancy or other sexually transmitted infections, or counseling on the use of contraceptives.
We looked at girls who got the HPV vaccine and those that did not. And we combed through the research databases to look for sexual activity related outcomes. This gave us a way to look at this question without having to directly discuss these questions of sexual activity.
And presumably a much more accurate one just because by asking questions directly the girls could either say yes I am sexually active when they’re not, or not sexually active when they are.
Right, those types of sort of social norms biases can affect these surveys.
Consistently those surveys found that girls reported they wouldn’t change their sexual activity. But now we have clinical outcomes that support that.
What were the numbers?
There were 1,398 girls that we identified, and 493 of them received the HPV vaccine. And of those many had received the other adolescent vaccines, like the meningitis vaccine. And there were 905 girls who did not receive the HPV vaccine but did receive one of these other routine adolescent vaccines.
And you looked at their behavior from age 11 to about 14 or 15 years?
Yes. And what we found was that over all there was no difference between the two vaccine groups in these outcomes.
What was interesting was that about ten percent of the girls overall had testing or diagnosis for pregnancy or sexually transmitted infections, or counseling on contraceptive use.
But we also found there were only eight girls out of almost 1,400 that either had a positive pregnancy test or a positive STD test.
At first 12-years old struck me as young to start the vaccinations.
I think it’s important to remember that the National Survey of Family Growth found that among 15 to 17-year-old females, 27 percent reported having sexual intercourse by that age range. And in these studies of HPV infection we found that even among 14 to 19-year-olds almost a third of them were infected with at least one HPV strain. When we find that sort of prevalence it’s an indication that vaccination early is important to ensure protection.
Have you noticed an earlier onset of sexual activity in American teenagers over the last, let’s say, twenty years?
Well actually we’ve seen rates of adolescent sexual activity declining. In 1995 35 percent of 15 to 17-year-olds reported being sexually active. And then that dropped down to 27 percent by 2006.
What are some of the other arguments against the HPV vaccine?
One of the concerns is that it’s a very new vaccine that may not have been studied well enough.
There were multiple clinical trials that occurred with tens of thousands of participants that were followed up for multiple years. So the vaccine was tested extensively before it was licensed and recommended for use. And now that it is recommended for use there have been a number of large studies that have looked at the safety of the vaccine.
The one thing that does tend to appear in these safety studies in an increased risk of fainting. So it is recommended that when a girl gets the HPV vaccine she should be monitored for about 10 to 15 minutes after she gets the vaccine.
But there is no increase in the risk of autoimmune disorders or other adverse outcomes.
Do you think that the results from your recent study will change the minds of the religious and conservatives?
I’m hoping it will help put parents minds at ease. The biggest thing that we’re hoping for is that physicians are willing to take this information and when they have adolescents coming into their office they can present that information to their patients and say this is a safe vaccine, this is an effective vaccine—and that it hasn’t been linked to earlier onset of sexual activity, or increased sexual activity.