Study: Less may be more for HPV protection
September 9th, 2011
06:28 PM ET

Study: Less may be more for HPV protection

A new study suggests that girls and women may not need all three recommended doses of HPV vaccine to get the necessary protection to prevent cervical cancer.

The human papillomavirus is the most common sexually transmitted disease according to the Centers for Disease control and Prevention  and the second leading cause of female cancer mortality worldwide, according to the World Health Organization.

There are currently two FDA-approved vaccines to protect against the types of HPV that cause most cervical cancers,  Gardasil and Cervarix.  While each vaccine uses different substances to rev up the immune system, both are given as shots and must be received in three doses over a six-month period, according to the manufacturers.

The cost of the vaccine has been an issue for poorer countries. But even in wealthier countries like the United States, getting girls and young women to come back for all three shots has proven to be quite a hurdle. Only 32% of 13- to 17-year-old girls get all three doses according to the Centers for Disease Control and Prevention.

So researchers wanted to find out if young women can get the same protection with fewer doses of the vaccine. Scientists studied more than 7,000 18-25 year-old women in Costa Rica who were already sexually active and were scheduled to get doses of the vaccine Cervarix or another (non-HPV) vaccine.After following the women for four years they found "two doses working really well in the short term," says lead study author Aimee Kreimer of the National Cancer Institute. She says even a single dose showed the same protection from cancer as three doses, but Kreimer says she's more cautious about the one-dose vaccine because usually to get adequate protection from a vaccine, people are given one dose to prime the body and then a booster to reinforce the immunity.

The study was published in the Journal of the National Cancer Institute, which is a publication of Oxford Press, not the NCI.

Gardasil was first approved in 2006 for females age 9 to 26.  Two years ago the FDA also approved the use of this vaccine in 9- to 26-year-old males, for the prevention of warts caused by HPV.

In 2009, the FDA approved Cervarix.  It is licensed for use in females aged 10 to  25.  The idea is to vaccinate young people before they become sexually active and could be infected.

The study in Costa Rica was started five years before Cervarix was approved and data from this clinical trial contributed to the approval of this vaccine, says Kreimer.  She says researchers studied only this vaccine  because clinical trials are very expensive and if they had included Gardasil the trial would have been too expensive overall.

However, the study authors do cite a study that found girls who received two and three doses of Gardasil has similar antibody titers (a measure of antibodies) several years after receiving the vaccinations. Merck, the manufacturer of Gardasil, tells CNN in a statement that based on the studies it has conducted, Merck continues to recommend the three-dose regimen for Gardasil.

Cosette Marie Wheeler, a professor in the University of New Mexico's Department of Pathology and Obstetrics and Gynecology, has studied HPV for more than 20 years. She writes in an accompanying editorial in JNCI that the results of the Costa Rican study must be viewed with caution in part because the study was composed largely of sexually active women aged 18 to 25 years.

Kreimer agrees, particularly because the women in this trial were healthy. "This should also be replicated in other populations," she says.

Perhaps the best way to confirm that fewer doses can provide very good protection against cervical cancer would be to conduct larger studies, as Wheeler puts it in her editorial, "to evaluate the efficacy of one-, two-, and three-dose regimens in young adolescent girls."  But she recognizes that this is expensive, so she suggests girls and women who have already received some of the vaccine should be followed and studied to determine how effective the vaccine is for them.

More than 80% of cervical cancers occur in developing countries according to the WHO, because most women in those areas do not have the opportunity to be screened for early signs of cancer using a pap smear. Vaccines could prevent girls from being infected with the virus in the first place.

soundoff (32 Responses)
  1. MrSnow

    it's sad that this can only get funding and popularity as cancer prevention, but the moment someone acknowledges that it is primarily an STD vaccine, the western world tenses up and ignores it.

    If you realistically remember yourself in high school and college, you'll realistically want to protect your children.

    September 9, 2011 at 21:53 | Report abuse | Reply
    • Michelle

      Realistically, I wasn't "doing the deed" in high school. If I used myself as an example, I'd assume the rest of the people on this planet were intelligent, rational people with self-control and priorities in order, including teenagers.

      September 12, 2011 at 14:12 | Report abuse |
  2. TheException

    One shot of the Gardasil vaccine apparently wasn't effective in my case. I got HPV from my first and only partner, even though I got the first shot about a month and half prior to our first time. Of course, since neither of us had symptoms I had no idea I had it and went ahead and got the last two shots. Now a few years later, I have abnormal cervical cell growth and have had to have multiple painful biopsy and treatment procedures. Turns out its all due to a strain of HPV that is supposed to be prevented by the vaccine. Obviously the plural of anecdote isn't data, but based on my experience, I think they need to do more in-depth studies before advocating reducing the number of shots.

    September 10, 2011 at 00:54 | Report abuse | Reply
    • Anon

      What probably happened in your case is that your body didn't create enough or any antibodies on the first dose. For most vaccines the body will start responding on the second or third dose, hence the three dose recommendation. Unfortunately if you get the virus before you get finish the vaccine, then completing the set is moot. I was told this by my own doctor after the same situation happened with me. (diagnosed after first dose) Unfortunately there are no tests available for males, so a woman has no way of knowing if she's gotten HPV from a partner unless she gets herself tested.

      Of course, condoms are an effective method to preventing most STD's, including HPV. However, our country is very spotty on contraceptive education. This leads to many people either using condoms improperly, or not using them at all.

      Aside from the 4 strains that cause cervical cancer, HPV is like the common cold of STD's. Most cases clear up within a year or two. However, one should always be proactive in their health. I hope that your health remains good and that your body heals from this. 🙂

      September 10, 2011 at 13:37 | Report abuse |
    • The Rule

      The original pre-approval clinical trials of Gardasil showed that in women who were already infected with the strains of HPV contained in the vaccine before vaccination, the risk of cervical abnormalities/cancer was INCREASED 44%. The vaccine was also recently found to be contaminated with HPV DNA, contrary to the manufacturer's claims. Over 20000 adverse events have been reported, including 100 deaths and numerous cases of vaccine failure/cervical abnormalities post-vaccination have been found. Do your research before getting this vaccine! SaneVax.org is a good place to start.

      September 10, 2011 at 16:07 | Report abuse |
    • reallynow

      Check out the ingredients and side effects of those vaccines. Just like all other vaccines, full of toxins and ineffective. Just check out the horror stories. Taking good care of yourself is the best form of prevention for any disease.

      September 11, 2011 at 09:53 | Report abuse |
  3. Coralie

    This news from yesterday worries me.

    "At the request of medical consumers concerned about HPV vaccine safety and efficacy, SANE Vax Inc. has retained a private laboratory to test a number of samples of HPV 4 Gardasil™ (Merck) for possible contamination by human papillomavirus (HPV) DNA in the vaccine lots distributed to physicians.

    The laboratory has informed SANE Vax Inc. that one hundred percent of thirteen (13) samples of Gardasil™ taken from lots #1437Z, #1511Z, # 0553AA, #NL35360, #NP23400, #NN33070, #NL01490, #NM25110, #NL39620, #NK16180, #NK00140, #NM08120 and #NL13560, currently being marketed in the U.S.A., Australia, New Zealand, Spain, France, and Poland have been found to be positive for HPV DNA."

    September 10, 2011 at 21:23 | Report abuse | Reply
    • Anon

      Well. I guess I'll know for sure when I get my next pap done. :/

      September 10, 2011 at 23:43 | Report abuse |
    • Wes

      What part of the viral DNA was present? That is important. Just because there is viral DNA doesn't mean it is dangerous. The only HPV DNA used in the manufacturing process seems to be the part coding for the coat particles which are what give immunity. So if that is present it is not an issue.

      September 11, 2011 at 15:28 | Report abuse |


    September 11, 2011 at 00:48 | Report abuse | Reply
    • Yermama

      Wake up. The LEAD RESEARCH/DEVELOPMENT Dr. for this very vaccine says it's not effective and the side effects are more harmful than actually getting cervical cancer. Don't dispense advice which you are clearly not informed on! Oh yeah, and WAKE UP! Looks like the lights are out in your head. There's a lot more that this dr. has to say that's not in this article. Read up.

      September 11, 2011 at 11:31 | Report abuse |
  5. Francis

    @Coralie OMG... I had my oldest son vaccinated last year when he was 11. I had been thinking of making my second son an appointment to start his first dose of Gardisil but after reading your comment I may decide to wait.

    September 11, 2011 at 06:59 | Report abuse | Reply
  6. Jon

    This vaccine does not have the best track record as far as side effects and long term health effects. Couple that with the fact that 80% of people will get HPV at some point in their life and you start to wonder if it's worth it. I would suggest to anybody who considers getting the HPV shot to really do their homework outside of just what the CDC says

    September 11, 2011 at 08:35 | Report abuse | Reply
  7. reallynow

    Here is a great web site with facts and information on why vaccinating is bad, unnecessary and can be deadly: http://www.vaccinationcouncil.org/

    September 11, 2011 at 09:55 | Report abuse | Reply
  8. ARt

    This is about protecting your child from future cancer causing viruses that can destroy fertility and possibly their life. More research needs to be done.

    September 13, 2011 at 01:14 | Report abuse | Reply
  9. ick

    Let them eat cake. I would sooner tax a corporate jet than miss out on one shot..what a sick society.

    September 28, 2011 at 16:26 | Report abuse | Reply
  10. ick

    But what happens in 5 years when the shot wears off? Merck, you need to answer this...

    September 28, 2011 at 16:28 | Report abuse | Reply
  11. JacobMichael

    It's very sad to see the anti-vaccine hysterics show up. We have an opportunity to prevent not just cervical, anal and penile cancer with this vaccine. We can prevent head and neck cancers that are caused by HPV with this vaccines. Have you not been reading the news and seeing these are on the rise? The HPV virus likes mucous membranes. That means the mouth and throat. Oral contact spreads the virus to these areas. The reports of danger with the HPV vaccine are from ignorant people who do not even understand how vaccines work. Watch this and then make your own decision based on facts, not hysteria.

    May 6, 2013 at 13:09 | Report abuse | Reply
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