February 5, 2009

Who Should Receive the HPV Vaccine?

There are 30 to 40 HPV (human papillomavirus) types that infect the genital area. Fifteen to 20 of these types—especially types 16 and 18—can be factors in the development of cancer in the area. Essentially, all cervical cancer is caused by HPV viral infections, and although only 10,000 cases per year occur in the United States, 500,000 cases occur world wide. Many of the non-cancer forming types of HPV (for example, types 6 and11) produce wart-like lesions.

HPV infection is the most common cause of an abnormal Pap test. Precancerous changes on the cervix caused by HPV and picked up by the Pap test account for 300,000 new cases of high-grade precancer dysplasia per year, and another 1.4 million new cases of low-grade precancer annually. In addition, there are approximately 1 million new cases of genital warts diagnosed each year.

Gardasil® (Quadrivalent Human Papillomavirus [types 6, 11, 16, 18] Recombinant Vaccine), the vaccine currently available to prevent HPV infection, renders protection against the HPV virus types 6,11,16, and 18, which covers the most common types involved in cancer, precancer, and wart lesions. This vaccine is currently approved for girls and women ages 9 to 26 years. Studies are underway to secure approval for older women and males.

These viruses are very easily acquired. By age 50, at least 80 percent of women will have acquired a genital HPV infection. Transmission through intercourse is most common, but many experts feel that the virus can be carried from one partner to another by fingers, sex toys, and other objects. It is highly infectious and very prevalent, especially among 15 to 24 year olds, where it is estimated that 9 million are currently infected in the United States. In studies of women 25 years of age and younger, prevalence rates range from 28 to 46 percent.

The HPV vaccine is manufactured from the protein capsule of the viral particle grown in yeast cells and contains no viral DNA and RNA, so there is no danger of transmitting the disease with the vaccine. The vaccine does contain an aluminum salt as an adjuvant, and rare allergies to this substance have been reported. In general, the vaccine is very safe and highly effective when administered in three doses over a six-month period. Each 0.5 ml dose is given into a limb muscle.

Gardasil should be given to all girls and women regardless of previous sexual activity or documented HPV infections. Females who have already been infected with one of the four viral subtypes contained in the vaccine can be protected against those subtypes to which they have not been exposed. The earlier in life the vaccine is administered, the better the immune response as measured by studies of antibody levels. Timing of doses is somewhat flexible, allowing for college holidays and other commitments.

The cost of the vaccine alone is approximately $150.00 per dose or $450.00 for three doses. When a girl or woman is within the CDC-approved age group of 9 to 26 years, most health insurance plans cover the cost. The vaccine is contradicted in patients allergic to yeast or aluminum and it is also not administered in pregnancy.

Information on whether or not a “booster shot” will be necessary in the future to maintain immunity has yet to be determined. Studies out as long as seven years have not indicated such. Hopefully, the studies being done on males will be adequate so they too can be immunized. As always, consult your physician if you have questions.

The Gynecologic Oncology Group—a national non-profit organization dedicated to promoting excellence in the quality and integrity of clinical and basic scientific research in the field of gynecologic malignancies—offers answers to important questions concerning gynecologic oncology. For more information, visit www.gog.org.

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Tags: Cervical Cancer, Uncategorized