Girls may not have riskier sex after HPV vaccination
Gerald Hurowitz, M.D.·Published 15 October 2012·8 min read
Key points
Girls who had been vaccinated against human papillomavirus (HPV) weren't more likely to get other sexually transmitted infections or to become pregnant, in a new study from Georgia.
Human papillomavirus is the main cause of cervical cancer.
Both vaccines are very effective against HPV types 16 and 18, which cause most cervical cancers.
Gardasil also protects against HPV types 6 and 11.
Girls who had been vaccinated against human papillomavirus (HPV) weren't more likely to get other sexually transmitted infections or to become pregnant, in a new study from Georgia.
That goes against worries on the part of some that getting the vaccine - which is supposed to ultimately help prevent cervical cancer - would encourage girls to become sexually active or engage in riskier sex than they otherwise would.
"Some parents have expressed it as a concern," said Saad Omer, an infectious diseases and vaccine researcher from Emory University in Atlanta who worked on the study.
"Parents can be reassured at least based on the evidence that young girls who receive HPV vaccines did not show increased signs (of) clinical outcomes of sexual activity," he told Reuters Health.
The vaccine, which has been recommended for 11- and 12-year-old girls in the U.S. since 2006, is still controversial, and only about half of girls start the series of shots.
One of the arguments against it has been that vaccination will make pre-teens feel a false sense of security when it comes to sex.
The Centers for Disease Control and Prevention now calls for boys to get vaccinated as well.
What is human papillomavirus (HPV)?
Human papillomavirus is the main cause of cervical cancer. About 12,000 women in the United States get cervical cancer each year, almost all of it associated with HPV.
HPV affects both men and women. It's the cause of anal, mouth and throat, penile, vaginal, and other cancers, as well as genital warts, which are found in about 1 in 100 sexually active adults in the United States.
If you think it's unlikely that you're infected, consider this: HPV is the most common sexually transmitted infection (STI), and most infected people don't even realize they have it or that they're spreading it to their sexual partners. It's so commonplace that at least 50 percent of sexually active men and women get the virus at some point in their life.
"Sexually active" doesn't mean having sex with lots of people. It simply means that you've had sex with at least one person. And if that person had sex with at least one other person, you're at risk.
Of course the more people you've had sex with, the greater the risk – but the only people fully protected from HPV are monogamous partners who have never had sex with anyone else. As a result, about 20 million Americans are already infected with the virus, and 6 million more become infected every year.
HPV typically spreads through vaginal and anal sex, and oral sex. It can be transmitted between male and female partners and between same-sex partners. You can have HPV even if you haven't had sex for many years or haven't had sexual contact with an infected person for many years.
Written and revised by
Gerald Hurowitz, M.D.
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Unfortunately, there's no routine way to be tested for HPV. The only approved HPV tests available are used for screening women for cervical cancer. And there's no approved HPV test for men.
There are several types of HPV and you can become infected with more than one type. Don't confuse HPV with herpes or HIV (the virus that causes AIDS), though. All are sexually transmitted but each causes different health problems.
The two HPV vaccines
Two HPV vaccines are licensed by the FDA and recommended by the CDC: Gardasil and Cervarix.
How the vaccines are similar
Both vaccines are very effective against HPV types 16 and 18, which cause most cervical cancers. Both are very safe. Both are made with very small parts of the human papillomavirus (HPV) that cannot cause infection with HPV, so neither vaccine can cause HPV infection. Both are injected and require three doses.
How the vaccines are different
Gardasil also protects against HPV types 6 and 11. These HPV types cause most genital warts in females and males. Gardasil has also been shown to protect against anal, vaginal and vulvar cancers. The vaccines have different adjuvants. (A vaccine adjuvant is a substance that's added to the vaccine to improve the body's immune response.)
For the new study, Omer and his colleagues analyzed databases from Kaiser Permanente Georgia, a managed care organization covering the Atlanta area. Out of 1,398 girls who were 11 or 12 when they saw their doctors in 2006 and 2007, 493 got at least one dose of the HPV vaccine.
Based on records of their primary care visits, 107 of the girls included in the study were given a pregnancy test through 2010, and 55 were tested for Chlamydia.
The human papillomavirus (HPV) is a common virus. There are more than 100 different types of HPV, at least 40 of which are spread through sexual contact and can infect the genital area.
Like other infections, HPV may go away without any treatment or problems - but certain low-risk types (e.g. types 6 and 11) may cause warts in the genital area, and at least 15 high-risk types of HPV (e.g. types 16 and 18) may cause cancer. There is no medicine that can cure the virus.
Girls who did or didn't get the HPV vaccine were equally likely to be tested for both.
Two girls in each group got pregnant during the study. One girl who'd been vaccinated was diagnosed with Chlamydia, compared to three unvaccinated girls, according to findings published Monday in the journal Pediatrics.
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Omer's team didn't have any data on how many of the girls were sexually active during the study period. The researchers also couldn't tell if the STI and pregnancy tests were part of standard clinical procedures or if girls were tested because they were sexually active or had symptoms.
Divya Patel, an ob-gyn researcher from the University of Michigan in Ann Arbor, called the study a "really good first stab" at looking at the behavioral effects of HPV vaccination.
"But I felt that it didn't convey the full picture," she added.
For example, it's possible girls as young as 11 and 12 aren't even told what the vaccine is for, or only hear about it in the context of cervical cancer.
MYTH: The Pap test tells you whether you have HPV or other STIs
FACT: The Pap test detects cell changes in the cervix (located at the end of the vagina). It doesn’t tell you if you have an STI, including HPV. Your health-care professional can test for sexually transmitted infections as part of a pelvic exam or separately, but you need to ask for it.
Right now, in Canada, there is an HPV test that can be used to detect high-risk types of HPV (the ones that can cause cancer). A doctor might decide you should have an HPV DNA test after a Pap test comes back showing abnormal cells. This test is not available in all parts of Canada and the cost is not generally covered by public health insurance. The HPV test is usually recommended for women over 30 whose Pap results show specific abnormalities. The test is not recommended for women under 30 because some strains of HPV are likely to clear up on their own within 2 years.
MYTH: HPV vaccination can protect me from HPV and other STIs
FACT: There are more than 100 different types of HPV. At least 40 of these types are spread through sexual contact and can infect the genital area.
Four types of HPV cause the majority of genital warts (types 6 and 11) and most cases of cervical cancer (types 16 and 18). Two vaccines are now available in Canada; one protects againsst types 16 and 18 and the other against all four types.
These vaccines do not protect against the other types of HPV or any other STI.
MYTH: I don’t need the HPV vaccine because I am not having sex
FACT: Vaccination works best if you have not been exposed to any types of HPV preventable by the vaccines. If a young woman gets vaccinated early, before she is sexually active, she could be protected from up to 4 types of HPV that she could be exposed to when she does have sexual contact with a partner. Studies on the vaccines have shown that it is most effective for girls aged 9 to 13, and it protects young women for a minimum of 5 years. It may protect for much longer, but more research is needed to confirm this.
MYTH: HPV vaccination can prevent pregnancy
FACT: HPV vaccination is not a contraceptive. You still need to protect yourself from unplanned pregnancy by using some form of birth control.
MYTH: HPV vaccination infects you with the virus, so you can become immune to it
FACT: These vaccines do not contain any live or dead virus and cannot infect you with HPV.
MYTH: After being vaccinated, you no longer need Pap tests
FACT: HPV vaccination does not replace the need for regular Pap tests. The Pap test does not diagnose an HPV infection. It is used to detect cell changes in a woman’s cervix before they develop into cancer. Regular Pap tests are a key part of a healthy woman’s life, whether or not she has had the HPV vaccination. These vaccines do not protect you from all types of HPV, so there is still a risk of developing cervical cancer if you are infected with one of these other types.
"I'd be really surprised if kids this age are knowing that, ‘I got a vaccine for HPV and it's a sexually transmitted disease,'" Patel, who wasn't involved in the new study, told Reuters Health.
Looking at pregnancy tests from primary care doctors' offices is also limiting, she said, because girls might be more likely to go to school health clinics, or buy a test off the shelves, in those situations.
She said future studies like this one, but in different locations and in older girls, will be needed to help piece together what's going on.
The researchers agreed that there are other issues limiting the popularity of the HPV vaccine besides concerns about a spike in sexual risk-taking.
"I think that perception of risk (with HPV) is not quite there. People don't really consider themselves at risk, or they're not concerned," maybe because it's so common, Patel said.
"We need to be aware of how to prevent it, and vaccination is the best way to do that."
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