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On June 8, 2006 the Food and Drug Administration (FDA) approved
Gardasil, the world's first cancer vaccine. Gardasil is used
to protect girls and women, ages 9 through 26, from the two
types of human papillomavirus (HPV) infection that are responsible
for most cervical cancer cases. It is not effective, however,
against other types of HPV that cause approximately 30% of cervical
cancers. For that reason, administration of the HPV vaccine
needs to be combined with regular screening for cervical cancers
(Pap smears) in order to detect cervical cancer in its early
stages when treatment is most effective.
HPV is the name for a group of viruses that cause both cervical
cancer and genital warts.1 HPV exists
in more than 120 forms. Although many types of HPV do not increase
the risk of cancer, about 30 types of HPV spread through sexual
contact greatly increase the risk of cancers around the anus
and the genitals in both males and females. Of all the sexually-transmitted
types of HPV, two types, 16 and 18, are responsible for approximately
70% of all cases of cervical cancer. Gardasil protects against
infections caused by both of these types. The vaccine also provides
immunity to HPV types 6 and 11 that have been identified as
causing approximately 90% of all cases of genital warts, but
do not cause cancer.1
What makes HPV especially dangerous is that many of the approximately
6 million people who are infected with genital HPV each year
in the United States have no symptoms and therefore do not even
know that they are infected. Although most HPV infections are
short-term, women with persistent infections are at higher risk
for developing cervical cancer. Genital HPV infections cause
more than 10,000 cases of cervical cancer per year.
Cervical cancer is the second most common cancer in women worldwide,
killing approximately 288,000 women each year, and about 3,700
women in the U.S. Research shows that more than 90% of women
who develop cervical cancer have had a genital HPV infection
at some point in their lives. Public health officials in the
U.S. encourage women to have a Pap smear at least every 3 years
beginning at age 18, or once they become sexually active. Using
Pap smears to detect cervical cancer or precancerous lesions
has significantly decreased the number of deaths from cervical
cancer. According to the Centers for Disease Control and Prevention
(CDC), deaths from cervical cancer are more likely among women
who are uninsured or underinsured. More than half of all U.S.
women diagnosed with cervical cancer reported not having had
a Pap smear in the last 3 years prior to diagnosis.2
All women will still need regular Pap smears, whether or not
they are vaccinated with the HPV vaccine. Approximately 30%
of cervical cancers are not linked to the HPV types 16 and 18
that the vaccine protects against. In addition, women who are
beyond the age of vaccination or who have already been exposed
to HPV will also continue to need regular Pap smears. It is
important to note that cervical cancer has a long lag time between
exposure to HPV and the onset of disease, so women may incorrectly
assume they are no longer at risk because they are not sexually
active or have been in a monogamous relationship.
The vaccine data thus far are short-term, so it is unknown whether
the immunity to HPV will last for more than the 4.5 years observed
in clinical trials.3, 4
Patients may need a booster shot for longer-lasting HPV prevention.
This is a concern, because the initial vaccine must be administered
three times over a six-month period, and can cost as much as
$400 for the 3 shot series. The relatively high cost of the
vaccine and the unknown cost of booster shots raise concerns
that uninsured women and less affluent women will not be able
to afford to protect themselves from HPV and cervical cancer.5
National Recommendations
On June 29, 2006, the CDC's Advisory Committee on Immunization
Practices recommended that the vaccine be given routinely to
all girls ages 11 and 12. The U.S. Department of Health and
Human Services accepted the Committee's recommendation and most
health insurance providers are expected to add Gardasil as a
coverage option for consumers.6
However, it is estimated that 11 to 15% of all children with
health insurance are under plans that do not include coverage
for routine vaccinations.7, 8
The CDC Committee has also recommended that the HPV vaccine
be included in the Vaccines for Children Program, the federal
program which provides free vaccinations to children 18 years
of age and under. Children who are uninsured, on Medicaid, protected
by the Indian Health Services Act, or underinsured patients
at Federally Qualified Health Centers and Rural Health Clinics
are eligible to receive program services.9
Approximately 41% of all childhood vaccines in the United States
are purchased by and administered through the Vaccines for Children
Program.10
Should the Vaccine be Mandatory?
If the vaccine is accessible and affordable to girls and women
across the country, it could result in a very substantial decrease
in cervical cancer. Requiring the vaccine for school attendance,
particularly for pre-adolescents, would be the best way to ensure
that most girls are protected, regardless of their economic
status. Research has shown that immunizations required for school
attendance are the most effective means of ensuring widespread
use of vaccines for children and adolescents.11
That is why a policy that requires the HPV vaccine to be mandatory
would be much more effective at boosting the vaccination rate
than a policy that simply endorses the CDC Advisory Committee's
recommendations. However, it is up to each state to decide whether
or not to require the HPV vaccine for school enrollment.12
Mandatory requirements are controversial, because some people
believe that if girls are given the HPV vaccine at a young age,
they will be less worried about the risks of sexual activity
and therefore be more promiscuous. However, this concern is
not supported by the data.13, 14,
15
In clinical trials, Gardasil was tested and found effective
in females less than 26 years of age. It is only effective in
preventing infection if it is given before infection occurs.
That is why it is important to provide the vaccine before sexual
activity begins. Research indicates that 13% of U.S. girls are
engaging in sexual activity by age 15, which is why Merck and
many public health officials are recommending the vaccine's
use at age 11 or 12.8
If someone has already been infected with one HPV type, the
vaccine will not prevent disease from that type.16
The vaccine's ability to prevent infections and other complications
resulting from HPV types 6, 11, 16, and 18 in women without
prior exposure to these types is a significant breakthrough,
especially since the CDC estimates that 80% of all women in
the U.S. will have had a genital HPV infection by age 50.17
The chances of HPV and cervical cancer increase with the number
of sexual partners. As with any sexually transmitted disease,
all it takes is exposure to one infected partner to acquire
it.
Vaccination Effects and Safety
Minor side effects, such as pain or tenderness at the injection
site, were quite common. Other reactions, such as headache,
fever, nausea, and dizziness were no more likely after receiving
the vaccine than after receiving a placebo.18
Rare but serious side effects could, however, possibly become
obvious after the vaccine is more widely used.
While more research will be necessary to determine exactly how
long the vaccine will provide protection against HPV, one thing
is clear: since 70% of cervical cancer cases are caused by HPV
types 16 and 18, Gardasil has the potential to save women's
lives. That is why it is essential to ensure that the vaccine
is safe and effective over the long-term, as well as affordable
and accessible. Pap smears will still be necessary to diagnose
cervical cancer caused by types of HPV that are not prevented
by the vaccine.
Merck, the company that makes Gardasil, has been criticized
for the high cost of the product. The company has spent millions
of dollars on advertising and donations to politicians with
the authority to mandate these vaccines at the state level.
These criticisms are especially salient because Merck did not
fully disclose fatalities in a study of one of their most popular
prescription drugs, Vioxx.19 With
Gardasil, as is always the case with new medical products, the
safety and risk information available to health professionals
and patients is almost entirely dependent on the information
reported by the company that makes the product.
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References:
1. Stevens, L.M. (2002). JAMA Patient Page: papillomavirus. JAMA, 287(18), 2452.
2. Centers for Disease Control and Prevention, Division
of Cancer Prevention and Control. HPV and The HPV Vaccine: Information
for Health Providers. Retrieved March 17, 2007 from http://www.cdc.gov/std/HPV/STDFact-HPV-vaccine-hcp.htm#provhpvrec
3. American Cancer Society. (2006, April 13). HPV vaccine
keeps working for years. Retrieved June 19, 2006 from: http://www.cancer.org/docroot/NWS/content/NWS_1_1x_HPV_Vaccine_Keeps_Working_for_Years.asp
4. GlaxoSmithKline. (2006, April 6). Cervarix, GSK's
candidate vaccine for cervical cancer, demonstrated sustained efficacy
for up to 4.5 years and broader protection again cancer-causing HPV
types. Retrieved April 6, 2006 from: http://www.gsk.com/media/archive.htm
and http://www.gsk.com/media/pressreleases.htm
5. Kaufman, M. (2006, June 9). FDA approves vaccine
that should prevent most cervical cancers. The Washington Post,
p. A01
6. Brown, D. (2006, June 30). HPV vaccine advised for
girls. The Washington Post, p. A5.
7. Institute of Medicine. (2003, August). Financing
vaccines in the 21st century: Assuring access and availability. Retrieved
June 30, 2006 from: http://www.iom.edu/Object.File/Master/14/454/VaccFinancelayout.pdf
8. Davis, M.M. & Fant, K. (2005). Coverage of vaccines
in private health plans: What does the public prefer? Health Affairs,
24(3), 770-780.
9. Centers for Disease Control and Prevention. Vaccines
for Children Program Parents' Home Page: Q & As from Parents. Retrieved
June 30, 2006 from: http://www.cdc.gov/nip/vfc/Parent/parent_home.htm
10. Lieu, T.A., McGuire, T.G., & Hinman, A.R. (2005).
Overcoming economic barriers to the optimal use of vaccines. Health
Affairs, 24(3), 666-680.
11. Dailard, C. (2006). The public health promise and
potential pitfalls of the world's first cervical cancer vaccine. Guttmacher
Policy Review, 9(1), 6-9.
12. Bridges, A. (2006, June 8). FDA approves cervical
cancer vaccine. The Washington Post Online. Retrieved June
8, 2006 from: http://www.washingtonpost.com
13. Steinbrook, R. (2006). The potential of Human Papillomavirus
vaccines. The New England Journal of Medicine, 354, 1109-1112.
14. Bruckner, H. & Bearman, P. (2005). After the promise:
The STD consequences of adolescent virginity pledges. Journal of
Adolescent Health, 36, 271-278.
15. HPV vaccine unlikely to increase teen sexual behavior,
research says. Retrieved March 17, 2007 from http://www.medicalnewstoday.com/medicalnews.php?newsid=44854
16. Centers for Disease Control and Prevention. (August
2006). CDC Fact Sheet on HPV and HPV Vaccine. Retrieved from: http://www.cdc.gov/std/HPV/STDFact-HPV-vaccine-hcp.htm
17. Centers for Disease Control and Prevention. (n.d.).
CDC Fact Sheet on Genital HPV Infection. Retrieved June 8, 2006 from:
http://www.cdc.gov/std/hpv/default.htm
18. U.S. Food and Drug Administration. (2006, May 18).
Vaccines and Related Biological Products Advisory Committee (VRBPAC)
background document: Gardasil HPV quadrivalent vaccine. Retrieved June
14, 2006 from: http://www.fda.gov/ohrms/dockets/ac/cber06.html#VaccinesandRelatedBiological
19. Tanne, J.H. (2006). NEWJ stands by its criticism
of Vioxx study, British Medical Journal, 332:505.
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