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Ask the Experts

HPV Vaccines: Do I Need All Three Doses?

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HPV vaccines involve getting three shots over six months, but what can you tell us about the recent news that only one dose of an HPV vaccine might actually be effective in protecting against cervical cancer?

When someone is infected with HPV, their immune system kicks in and creates an antibody response to the virus. The way the two HPV vaccines currently on the market work, of course, is by causing the body to create this antibody response without actually infecting those getting the shots with HPV. They trick the immune system into thinking HPV is present.

The vaccines actually cause an antibody response that’s much, much higher than what you see with natural infection.

This buzz is being spurred by research (Safaeian et al., Cancer Prev Res 2013) done with women who were part of large vaccine trials with Cervarix®, GlaxoSmithKline’s vaccine that covers the two HPV types found in about 70% of cervical cancers worldwide. While the study was designed to give women all three doses, for a variety of reasons (people drop out, miss follow-ups, become pregnant, etc.) a number of subjects received fewer than the intended number of shots.

So, the investigators running this study inadvertently ended up with a pool of women who received one, two, or three of the shots. This allowed for comparison of antibody levels in each group, not only to each other BUT also to women who have HPV and have an antibody response generated solely by natural infection.

They found that regardless of how many shots the women had, they still had a detectable antibody response that 1) was higher than what women with HPV develop on their own and 2) that lasted for at least four years.

The antibody response among those receiving two- or three-doses was similar, no significant difference at all. The response in those who only had one dose was lower than those receiving two- or  three-doses, but was still higher (and sustained) compared to antibody levels found in women who had HPV and had not received the vaccine.

This naturally raises the question as to whether or not fewer than three doses of an HPV vaccine will perhaps convey protection against the virus and cervical cancer. We don’t know for sure yet that it will, but this research is compelling. At this point, no changes are being made to the recommendation for three doses spaced over six months. Also keep in mind this study was done only with the GSK vaccine, not Merck’s Gardasil® vaccine that’s also commonly used around the world.

But who knows, if more studies also demonstrate value with fewer doses of the vaccines we may eventually see an alternative two-dose regimen available. In the meantime, those being vaccinated should still receive all three shots (and vaccinated women need to continue regular cervical cancer screening).

--The HPV Resource Center Staff



Should I let my teen get the HPV vaccine?

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My daughter is at an age (she’s 14) where the nurse practitioner who sees her wants to give her the HPV vaccine. I know it’s a good thing to do, but I’m a little uneasy about the message this might send. What if she’s less likely to use protection when she does have sex (hopefully that’ll be many years from now!!). I don’t want to be a prude and deny her something of value, but wow, vaccinate my baby against something you get from sex? Can you help me feel better about this? I feel guilty for not just taking the plunge and getting her the shot.

The important thing is that you are doing what all parents do: trying to make the best possible decisions about your child’s health and happiness, both now and for the future.

First, some background. HPV vaccines are recommended for use with all adolescents and young adults between the ages of 11 and 26. (HPV vaccines can actually be given as young as age nine). Why so young? The idea is to vaccinate and offer protection prior to the onset of sexual activity. Also, the vaccines generate a stronger response from the immune system of younger people, so the teen years are an ideal time to immunize against HPV.

As to your question, there is no evidence at all that young people who receive an HPV vaccine are more likely to have earlier or riskier sex. In fact, a recently published study (Bednarczyk, Pediatrics) that followed nearly 1,400 girls who were vaccinated against HPV at age 11 found –compared to girls of similar age who did not receive the vaccine- they were no more likely to engage in sex, become pregnant, or be diagnosed with an sexually transmitted infection. We often use the “seat belt” analogy here: just as wearing a seat belt won’t cause someone to suddenly drive faster or recklessly, neither will an HPV vaccine lead someone to become sexually active or be unprotected when they do.

Many parents also find that getting the HPV shot is a good time for discussions of sexually transmitted infections, and about sex in general. These discussions are a good way to share all that you’ve learned about HPV and other infections, as well as prepare your child to make healthy decisions about sex when she gets older.

By the way, the HPV vaccine is also recommended for boys. So, if you have a son, consider the vaccine for him as well.

We know that the HPV vaccine is safe for young people. Millions of doses of HPV vaccines have been safely given around the world. In some places, we are already seeing a reduction in HPV infections and in conditions associated with cervical cancer. If you want to learn more, read ASHA’s HPV Vaccine FAQ.

J. Dennis Fortenberry, MD, MS
Indiana University School of Medicine


Did my husband cheat?

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I recently had an abnormal Pap smear and, on follow-up, was confirmed to have abnormal cells caused by HPV. I don’t believe my husband has cheated on me, but the material I can find on the Internet really has conflicting information – some sites say you can have HPV for weeks, months, or even years before it’s diagnosed, but others say it usually shows up in a few months! Who’s right? I’ve had regular Pap smears throughout my adult life, too.

This is a common question that inevitably seems to emerge when HPV is found with someone in a long-term and (it’s assumed) monogamous relationship. First, it’s important to stress that Pap smears are not specific tests for HPV. Rather, they are designed to detect “disease” of the cervix, for example, abnormal cell changes that are precursors to cervical cancer.

Also, while Pap tests deserve enormous credit for greatly reducing cervical cancer rates in countries that have widespread screening programs, it should be noted they aren’t very sensitive, and can often miss disease that is present. The success Pap smears have as a tool for reducing cervical cancer is due to consistent, regular screening coupled with the fact cervical cancer tends to progress fairly slowly, often taking many years to become invasive.

You’re right about the information being confusing. While the average “latency” period of the virus is often thought to be anywhere from one to eight months, it can actually vary widely. Exactly “how” widely? It’s difficult to say with certainty, but experts typically agree it may take years after exposure before lesions associated with HPV (that is, warts or cell changes) are detected clinically.

Most women with HPV probably experience the virus as a transient infection that is either cleared or suppressed by the immune response, and will not be likely to ever have an abnormal Pap smear as a result.

However, HPV may actually exist in skin cells in what is known as “residential” infection. This is where the virus exists in basal epithelial cells in very small numbers, separate from human DNA, and can effectively hide from the immune system without causing disease (such as cervical cell changes) that Pap tests can detect. This may go on for an indefinite number of years. It’s difficult for researcher to pin down exactly why some experience lesions while other do not, but co-factors could involve smoking, pregnancy, stress, diet, or a host of other things that can affect the immune system.

We understand it’s frustrating that no one can offer a definitive response to your individual circumstances. If there was no reason to suspect infidelity prior to the HPV diagnosis, it’s difficult to look at this diagnosis, taken by itself, as an indication that anyone has been unfaithful. The “who” and “when” questions, however, may never truly be answered.


Anal warts without anal sex?

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Can a person be diagnosed with anal warts even if they’ve never had anal sex?

Anal warts are sometimes detected in those with no history of anal sex, but the exact route of transmission isn’t well defined. While most cases probably result from receptive anal intercourse, it’s possible that digital insertion poses a risk for HPV transmission. In terms of introducing HPV into the rectum via fingers, the risks may be more likely when warts are actually present at, or very near, the anus. The close proximity of a lesion (which is a reservoir of relatively large quantities of virus) may allow for the rectum to be exposed to infected skin cells by digital insertion, or perhaps through activities related to hygiene (such as wiping or cleaning). Also, perianal warts can develop from genital to anal contact without penetration, such as during sexual foreplay.


HPV in Relationships

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Within an established relationship, if one partner is diagnosed with any HPV disease what does that mean for the couple’s sex life?
The partners almost certainly will share an HPV infection, which could have been present indefinitely prior to any diseases being diagnosed. There seems little point, then, for those in on-going relationships to be fearful over continuing to be sexually active. Condom use probably isn’t necessary in relationships where HPV is shared. That HPV may be present for an extended interval before diagnosis of either the virus or related diseases is especially important for patients to understand, given that HPV detected within an established relationship often raises questions about sexual fidelity.

Does a partner of someone diagnosed with HPV need to be examined?
It isn’t commonly recommended that someone be examined when their partner is diagnosed with HPV, unless of course they notice any symptoms. This goes against the instincts shared by many that something, anything, has to be done! Since the vast majority of HPV are asymptomatic, and testing for the virus has limitations previously discussed, there’s typically no need for a partner to be evaluated.