Gardasil

What is Gardasil?

Gardasil (Merck & Co.), also known as Gardisil or Silgard, is a vaccine to prevent certain types of human papillomavirus (HPV), specifically HPV types 16, 18, 6, and 11. HPV types 16 and 18 currently cause about 70% of cervical, 26% of head and neck and many vulvar, vaginal, cancer cases. HPV types 6 and 11 cause about 90% of genital warts cases.

Gardasil can only prevent, not treat, HPV infections, so to be effective it must be given before HPV infection occurs. Some HPV strains are sexually transmitted. HPV-16 has a 60% per-couple transmission rate.

The U.S. Food and Drug Administration (FDA) recommends vaccination before adolescence and potential sexual activity.

The research that led to the development of the vaccine began in the 1980s by groups at the University of Rochester, Georgetown University, and the US National Cancer Institute (NCI). In 1991, Australian investigators at The University of Queensland found a way to form non-infectious virus-like particles (VLP), which could also strongly activate the immune system. However, these VLPs assembled poorly and did not have the same structure as infectious HPV. In 1993, a laboratory at the US National Cancer Institute was able to generate HPV16 VLPs that were morphologically correct. These VLPs were the basis for the HPV16 component of the Gardasil vaccine. The history of the discovery of this vaccine is described by McNeil. Upon commercialization of the vaccine, controversy involving intellectual property arose between the various groups that played a role in developing the vaccine.

Clinical trials

Merck & Co. conducted a Phase III study named Females United to Unilaterally Reduce Endo/Ectocervical Disease (FUTURE II). This clinical trial was a randomized double-blind study with one controlled placebo group and one vaccination group. Over 12,000 women aged 16–26 from thirteen countries participated in the study. Each woman was injected with either Gardasil or a placebo on Day 1, Month 2, and Month 6. In total, 6,082 women were given Gardasil and 6,075 received the placebo.

Merck has tested the vaccine in several hundred 11- and 12-year-old girls. On February 27, 2006, the independent Data and Safety Monitoring Board recommended the clinical trials be terminated on ethical grounds, so that young women on placebo could receive Gardasil.

Gardasil is made up of the following ingredients

  • Proteins of HPV Types 6, 11, 16, and 18
  • aluminum (as amorphous aluminum hydroxyphosphate sulfate adjuvant)
  • yeast protein
  • sodium chloride
  • L-histidine
  • polysorbate 80
  • sodium borate
  • water for injection.

Gardasil is given in three 0.5 milliliter injections over six months. The second injection is two months after the first, and the third injection is four months after the second shot was administered.

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Gardasil Safety

According to the Centers for Disease Control and Prevention (CDC), the vaccine was tested in thousands of females (ages 9 to 26). The Food and Drug Administration and the Centers for Disease Control and Prevention say that the vaccine has only minor side effects, such as soreness around the injection area. The FDA and the CDC consider the vaccine to be safe. It does not contain mercury, thiomersal or live virus or dead virus, only virus-like particles, which cannot reproduce in the human body. There have been reports that the shot is more painful than other common vaccines, and the manufacturer Merck partly attributes this to the virus-like particles within the vaccine. General side effects of the shot may include joint and muscle pain, fatigue, physical weakness and general malaise.

The most recent update on adverse events was published by JAMA and looked at data from the Vaccine Adverse Event Reporting System (VAERS), covering 12,424 reported adverse events after about 23 million doses of vaccine between June 2006 and December 2008. Although more than 20 women who received the Gardasil vaccine have died, officials maintain that there is no evidence that deaths or serious outcomes were connected to the shot. Likewise, although a small number of cases of Guillain-Barré Syndrome (GBS) have been reported following vaccination with Gardasil., there is no evidence linking GBS to the vaccine. Critics suggest that Gardasil should be used primarily in populations at high risk for cervical cancer.

This article is licensed under the Creative Commons Attribution-ShareAlike License. It uses material from the Wikipedia article on "Gardasil" All material adapted used from Wikipedia is available under the terms of the Creative Commons Attribution-ShareAlike License. Wikipedia® itself is a registered trademark of the Wikimedia Foundation, Inc.

Gardasil Long-Term Impact

One unknown property of the vaccines now being researched is the persistence of their protective effects. Since the Gardasil vaccine has been administered for only a few years now, it is unknown whether it will provide life-long immunity to recipients. In coming decades, further study will answer this question.

Whether the effects are temporary or life-long, widespread vaccination could have a substantial public health impact. 270,000 women died of cervical cancer worldwide in 2002. Acting FDA Administrator Dr. Andrew von Eschenbach said the vaccine will have "a dramatic effect" on the health of women around the world. Even in the United States, where screening programs are routine, the National Cancer Institute estimated that 9,700 women would develop cervical cancer in 2006, and 3,700 would die.

Merck and CSL Limited are expected to market Gardasil as a cancer vaccine, rather than an STD vaccine. It remains unclear how widespread the use of the three-shot series will be, in part because of its $360 list price ($120 each for three shots).

Both men and women are carriers of HPV. To eradicate these strains, males might eventually need to be vaccinated. Studies are being conducted to determine the efficacy of vaccinating males with the current vaccine.

Studies using different pharmacoeconomic models predict that vaccinating young women with Gardasil in combination with screening programs may be more cost effective than screening alone. These results have been important in decisions by many countries to start vaccination programs. For example the Canadian government approved $300 million to buy the HPV vaccine in 2008 after deciding from studies that the vaccine would be cost-effective especially by immunizing young women. Marc Steben, an investigator for the vaccine, wrote that the financial burden of HPV related cancers on the Canadian people was already $300 million per year in 2005, so the vaccine could reduce this burden and be cost-effective.

Since penile and anal cancers are much less common than cervical cancer, HPV vaccination of young men is likely to be much less cost-effective than for young women. The August 2009 issue of the Journal of the American Medical Association, JAMA, had an article reiterating the safety of Gardasil and another questioning the way it was presented to doctors and parents.

The new vaccine against 4 types of human papillomavirus (HPV), Gardasil, like other immunizations appears to be a cost-effective intervention with the potential to enhance both adolescent health and the quality of their adult lives. However, the messages and the methods by which the vaccine was marketed present important challenges to physician practice and medical professionalism. By making the vaccine's target disease cervical cancer, the sexual transmission of HPV was minimized, the threat of cervical cancer to adolescents was maximized, and the subpopulations most at risk practically ignored. The vaccine manufacturer also provided educational grants to professional medical associations (PMAs) concerned with adolescent and women's health and oncology. The funding encouraged many PMAs to create educational programs and product-specific speakers' bureaus to promote vaccine use. However, much of the material did not address the full complexity of the issues surrounding the vaccine and did not provide balanced recommendations on risks and benefits. As important and appropriate as it is for PMAs to advocate for vaccination as a public good, their recommendations must be consistent with appropriate and cost-effective use.

In an address at the 4th International Public Conference on Vaccination sponsored by the anti-vaccination group the National Vaccine Information Center in October 2009, Dr. Diane Harper stated that in countries where Pap smear screening is common, it will take vaccination of a large proportion of women in order to further reduce cervical cancer rates. She also stated that no efficacy trials for children under 15 have been performed.

This article is licensed under the Creative Commons Attribution-ShareAlike License. It uses material from the Wikipedia article on "Gardasil" All material adapted used from Wikipedia is available under the terms of the Creative Commons Attribution-ShareAlike License. Wikipedia® itself is a registered trademark of the Wikimedia Foundation, Inc.

Gardasil Usage

Gardasil is a prophylactic HPV vaccine, meaning that it is designed to prevent the initial establishment of HPV infections. For maximum efficacy, it is recommended that girls receive the vaccine prior to becoming sexually active. However, women who were already infected with one or more of the four HPV types targeted by the vaccine (6, 11, 16, or 18) were protected from clinical disease caused by the remaining HPV types in the vaccine.

Since Gardasil will not block infection with all of the HPV types that can cause cervical cancer, the vaccine should not be considered a substitute for routine pap smears.

Fewer HPV infections mean fewer complications from the virus and less time and money spent on the detection, work-up, and treatment of cervical cancer and its immediate precursor, cervical dysplasia. It prevents infertility caused by cervical biopsies and reduces the severe respiratory problems of children who are infected by HPV from their mothers. In addition, protection against HPV 6 and HPV 11 is expected to eliminate 90% of the cases of genital warts. Gardasil also protects against vulvar and vaginal cancers caused by HPV types 16 and 18.

Merck is seeking FDA approval to market Gardasil to older women aged 27 to 45. As of the early part of 2009, the FDA has requested final trial data before it approves the drug for this age group.

HPV infections, including HPV 16, contribute to some head and neck cancer. In principle HPV vaccines may help reduce incidence of such cancers caused by HPV, but this has not been demonstrated.

Use in males

Gardasil is also effective in males, providing protection against genital warts and some potentially precancerous lesions caused by some HPV types. An ongoing study of 4,065 males demonstrated the efficacy of Gardasil in males who did not have HPV infection prior to vaccination. and a FDA advisory committee recommended approval on September 9, 2009. The FDA approved this recommendation on October 16, 2009. In the UK HPV vaccines are already licensed for males aged 9 to 15 and for females aged 9 to 26.

Gardasil is in particular demand among gay men, who are at significantly increased risk for genital warts and anal cancer caused by HPV.

HPV vaccines may be useful in preventing anal cancer caused by HPV types 16 and 18. A 2005 study in San Francisco, California found that 95 percent of HIV-infected gay men also had anal HPV infection, of which 50 percent had precancerous HPV-caused lesions. Type 16 is also associated with oropharyngeal squamous-cell carcinoma, a form of throat cancer.

This article is licensed under the Creative Commons Attribution-ShareAlike License. It uses material from the Wikipedia article on "Gardasil" All material adapted used from Wikipedia is available under the terms of the Creative Commons Attribution-ShareAlike License. Wikipedia® itself is a registered trademark of the Wikimedia Foundation, Inc.