The approval of the first human papillomavirus (HPV) quadrivalent vaccine (Gardasil; Merck) last year represents a quantum step toward preventing the HPV infection”--”the main cause of cervical cancer.
About 20 million people are infected with this sexually transmitted disease in the United States, and about 6 million new people are infected every year. Of these, about 10,000 new cases of cervical cancer and 3700 cervical cancer–related deaths occur each year.
Women with HPV infection are at high risk for cervical cancer, the only cancer that is caused almost entirely by an infectious disease.
The new vaccine offers protection against HPV types 6, 11, 16, and 18. HPV types 16 and 18 are responsible for about 70% of cervical cancers; and HPV types 6, 11, 16, and 18 are responsible for 90% of genital warts and about 10% of abnormal Pap smears.
Other HPV vaccines are currently in different stages of investigation.
The approval of the HPV quadrivalent vaccine came after only 6 months of Food and Drug Administration (FDA) review under the recent priority-review system, which was designed to speed the process for drugs with significant health benefits. Therefore, long-term risks and benefits are still unknown.
The vaccine has been evaluated in more than 20,500 women, aged 16 to 26 years. Ongoing studies are investigating the use of the vaccine for boys and young men, as well as for women older than 26 years. Insufficient data discourages the use of the vaccine in these populations at this point.
The FDA based their approval on data from the 2 large phase 3 FUTURE (Females United to Unilaterally Reduce Endo-Ectocervical Disease) clinical trials, which showed that precancerous changes can be prevented by the vaccine (Table).
In a small subgroup of participants in FUTURE I who already had persistent infection with HPV, the disease may have worsened after receiving the vaccine.
Who Should Be Vaccinated? The HPV quadrivalent vaccine is indicated for girls and women aged 9 through 26 years. It is administered as 3 separate 0.5-mL dose intramuscular injections, with the second dose given 2 months after the first, and the third dose 6 months after the first, for a total cost of $360.
On June 29, 2006, 3 weeks after the FDA announced its approval of the HPV vaccine, the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices (ACIP) voted in favor of routine vaccination for all girls aged 11 or 12 years, although immunization can begin as early as 9 years at the discretion of the physician. The ACIP also recommended vaccination for girls and women aged 13 to 26 years who have not completed the vaccine series, ideally before they become sexually active, although women who are already sexually active should still be immunized.
The only contraindication to the vaccine is hypersensitivity to the active substances or excipients of the vaccine. If a patient develops symptoms suggestive of hypersensitivity after receiving any dose, additional doses should not be given. Injection-site reactions are the most common adverse events.
The vaccine does not protect women who are already infected with HPV, although more data are needed for definitive evidence, with some preliminary results showing benefits in infected women.
Since the quadrivalent vaccine does not prevent all types of HPV infection, routine Pap screening, as well as consistent condom use, are still recommended.
The mandate to vaccinate all young girls and women with this vaccine has caused some concern among certain medical and nonmedical groups, and among some parents.
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