On June 8, 2006, the US Food and Drug Administration (FDA) announced the approval and licensure of Gardasil™, the first vaccine designed to prevent both genital warts caused by the
human papillomavirus (HPV)
. HPV is the most common sexually transmitted infection (STI) in the United States, and the FDA’s rapid 6-month priority review process reflects the importance of this new vaccine in combating disease due to HPV.
Gardasil™ has been approved for use by females aged 9-26. The vaccine is a product of genetic engineering and is considered safe. Gardasil™ does not contain HPV. Rather, it uses a harmless viral protein to stimulate the immune system and create resistance against the virus. It is, therefore, not possible to become infected with HPV from the vaccine.
What Else Should I Know About Gardasil™?
The immunization is administered as three intramuscular injections in the upper arm or thigh over a six-month period–the second shot is given two months after the first shot, and the third shot is given four months later. During clinical tests, study participants reported only minor discomfort, which included mild to moderate pain at the injection site. Some study participants reported a low-grade fever after receiving the vaccine. But overall, evaluations of the vaccine thus far have not uncovered any serious adverse effects.
What the Studies Revealed
The makers of Gardasil™, Merck & Co., Inc, conducted four double-blind, placebo-controlled, randomized trials (one in the United States and three multinational) that included 21,000 women ages 16-26. These studies found that Gardasil™ was nearly 100% effective at preventing
caused by HPV types 6 and 11 (HPV types 6 and 11 cause approximately 90% of genital warts.)
Most significantly, the studies also showed that the vaccine appeared to offer protection against HPV types 16 and 18, which cause 70% of cervical cancers. The vaccine was found to prevent a precancerous condition of the cervix known as
, which may lead to cervical cancer if left untreated. Although there are other vaccines capable of reducing the risk of cancer (eg,
), this is the first vaccine ever developed and marketed to specifically lower the risk of a common cancer.
Merck also conducted two studies measuring antibody levels for HPV types 6, 11, 16, and 18 in girls ages 9-15 as compared to females ages 16-26. The immune response in the younger age group was similar to that of the older group, indicating that the vaccine should have similar effectiveness across both age groups.
More Key Points About Gardasil™
Gardasil™ is not a treatment, but a prevention measure. The vaccine will not help women who already have HPV types 6, 11, 16, and 18. However, most people do not contract all four at the same time, so the immunization would still be recommended as a preventive measure against the HPV types that a woman does not have. Also, Gardasil™ does not prevent infection with the other HPV types that are not contained in the vaccine. Therefore, the vaccine does not replace the need for routine
to screen for cervical dysplasia and cancer.
Women and girls allergic to yeast should not be immunized with Gardasil™. Also, although the clinical trials conducted by Merck did not show any adverse effects of Gardasil™ on pregnancy, the product is not recommended for pregnant women. Studies are underway to monitor pregnancy outcomes of women who were vaccinated with Gardasil™ during clinical trials, but did not know they were pregnant at the time of vaccination.
Social Implications and Possible Controversies
The FDA’s rapid approval process of Gardasil™ leaves scientists and the American public with some lingering questions. The long-term effectiveness of the vaccine remains unknown, and only after follow-up evaluations will its effectiveness be fully understood. Also, like any new drug, uncommon and long-term side effects are unknown until a generation of users can be observed. Further studies are being conducted on the efficacy and safety of Gardasil™.
The age that females should receive the vaccine is bound to be a sensitive issue. Vaccine advocates will point out that it is best for young girls to receive the vaccine before they become sexually active, because once they have sex they are at risk for HPV, and once you contract HPV the vaccine is no longer useful.
The FDA’s approval for the use of Gardasil™ by girls as young as age nine acknowledges statistics showing sexual activity beginning in adolescence. However, some parents, teachers, and health officials may object to adding Gardasil™ to the set of routine childhood immunizations out of concern that children would interpret such measures as permission to have sex. Merck is planning to market Gardasil™ as a cancer prevention vaccine, not an STI vaccine.
The cost of the vaccine is expected to be $360 per three-shot series, which would make it one of the most expensive vaccines ever manufactured. This significant cost may pose problems for state governments wishing to subsidize the vaccine and many families.
Gardasil™ was not approved for use in men, even though they are the cause of virtually all cases of HPV in women. HPV poses no risk of cancer in men. Merck and other drug companies are conducting additional studies evaluating the effectiveness and safety of Gardasil™ for males.
The Centers for Disease Control and Prevention (CDC) Advisory Committee on Immunization Practices plans to discuss Gardasil™ at its meeting on June 29, 2006, and will subsequently make recommendations for its use.
More on HPV: What It Is, Who Is At Risk, and How You Get It
The human papillomavirus lives on the skin or mucous membranes of infected individuals. Approximately 20 million Americans are infected with HPV. The CDC estimates that 6.2 million Americans are newly infected with genital HPV each year, and that over 50% of sexually active men and women will acquire an HPV infection at some point in their lives. By age 50, approximately 80% of American women will have become infected with HPV. Over 630 million people are infected with HPV worldwide.
Although HPV is extremely prevalent in the United States, most people have never heard of it. This is because there are often no symptoms, and many cases go away on their own. Although the body’s immune system is often effective in getting rid of many types of HPV, other types of HPV can cause genital warts and, more seriously, cervical dysplasia, a precancerous condition. Fortunately, the vast majority of HPV infections do not lead to cervical cancer.
The transmission rate of HPV is high because most people who are infected don’t know that they have HPV and therefore don’t take necessary precautions. Even more importantly, HPV is spread by skin-to-skin contact and not via blood or bodily fluids like most other STIs. Anyone who has ever been sexually active bears the risk of getting and passing on HPV. Because there are no symptoms, a person can have HPV for years and not know they are transmitting it through genital contact. Condoms are not entirely effective in preventing HPV infection because areas that are not covered may be infected. However, condom use has been associated with a lower rate of cervical cancer.
FDA licenses new vaccine for prevention of cervical cancer and other diseases in females caused by human papillomavirus: rapid approval marks major advancement in public health. FDA Press Release, June 8, 2006. Available at:
. Accessed June 13, 2006.
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provided by your physician. It is neither intended nor implied to be a
substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER
IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the
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