How Effective is Gardasil?

New Study Show Gardasil to Be Highly Effective

young woman receiving HPV vaccine
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How effective is the human papillomavirus (HPV) vaccine Gardasil? The results of two follow-up studies involving Gardasil, are in. The findings that confirm it is highly effective for preventing precancerous cervical lesions, especially for girls and young women who received it before they became sexually active.

What is the Gardasil Vaccine?

Gardasil is a vaccine that is designed to prevent two strains of the human papillomavirus known to cause cervical cancer (HPV-16 and HPV-18) and two strains known to cause genital warts (HPV-6 and HPV-11).

It is currently available to girls as young as nine years of age, but the target age is 11 to 12. The vaccine can be given up until 26 years of age.

The Gardasil vaccine has generated controversy for many reasons. Some people are generally opposed to vaccines and have fears about their effects. Other people are opposed to a vaccine that might prevent a sexually-transmitted virus, due to their moral objections and concerns about it being given to younger women. Scientists and the medical community want to ensure that the vaccines they give are effective in preventing disease and do not produce unwanted side effects. They continue to test them and study the populations who were vaccinated to see if the vaccine works and is safe.

What Did the Gardasil Studies Find?

Two Gardasil vaccine studies, titled Future I and Future II were featured in the May 10th, 2007, edition of The New England Journal of Medicine.

This journal publishes research papers after they have been analyzed by peers who ensure the research published is of high quality. Here are some key findings from both of the Future I and Future II studies on the Gardasil vaccine:

  • Gardasil was nearly 100 percent effective in preventing precancerous cervical lesions caused by the the strains that Gardasil protects against. It provides protection against two strains known to cause 70 percent of all cervical cancers and two strains known to cause 90 percent of all warts.
  • The Future I study found that Gardasil is also highly effective in preventing precancerous lesions that occur on or in the vagina, anus, and vulva.
  • Gardasil's effectiveness increased when given to girls and young women before they become sexually active.
  • Gardasil is less effective in preventing precancerous lesions in women already exposed to HPV strains 16 and 18, since you cannot vaccinate against an infection that is already present.

What Do the Gardasil Study Results Mean For You?

The findings of both studies support the use of the HPV vaccine, especially when given to young women before they become sexually active. Gardasil is extremely effective in preventing several (but not all) of the strains of HPV known to cause cervical cancer and genital warts. Therefore, Pap smears are still necessary. With the availability of the HPV test and more data, the timing of Pap smears has been changing. Check for the latest recommendations and discuss any concerns with your doctor.


The Future II Study Group, "Quadrivalent Vaccine against Human Papillomavirus to Prevent High-Grade Cervical Lesions." New England Journal of Medicine Vol. 356, No. 19: 1915-1927 May 10, 2007.

Suzanne M. Garland, M.D., Mauricio Hernandez-Avila, M.D., Cosette M. Wheeler, Ph.D., Gonzalo Perez, M.D., Diane M. Harper, M.D., M.P.H., Sepp Leodolter, M.D., Grace W.K. Tang, M.D., Daron G. Ferris, M.D., Marc Steben, M.D., Janine Bryan, Ph.D., Frank J. Taddeo, Ph.D., Radha Railkar, Ph.D., Mark T. Esser, Ph.D., Heather L. Sings, Ph.D., Micki Nelson, B.S., John Boslego, M.D., Carlos Sattler, M.D., Eliav Barr, M.D., Laura A. Koutsky, Ph.D."Quadrivalent Vaccine against Human Papillomavirus to Prevent Anogenital Diseases." New England Journal of Medicine Vol. 356, No. 19:1928-1943. May 10, 2007.

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