This is the 62^nd article written by the Pediatric Group, P.A. for Princeton Online

 

The papilloma family of viruses is responsible for a variety of lesions on skin and cavity linings. Different subtypes are responsible for common warts, plantar warts, genital warts, cervical cancer, vaginal cancer, vulvar cancer, penile cancer, oropharyngeal cancer and anal cancer. Other agents can cause most of these cancers, but HPV is responsible for 99.7% of cervical cancers, 90% of squamous cell carcinoma (a type of skin cancer) and 70% of anal cancers. This virus is transmitted by skin contact (sexual contact in the instance of genital diseases) and is highly contagious. Condoms, although strictly recommended for people who are sexually active, are not particularly effective in preventing transmission since infection occurs by skin to skin contact rather than by semen or vaginal fluid to skin contact. The virus enters the body through microscopic breaks in the skin that occur during sexual activity or other cutaneous contact (e.g., oral-genital, hand-genital). It is estimated that 80% of all females over the age of 50 in the US are infected with this virus, amounting to 20 million cases in the US. Each year 6.2 million new infections occur, mostly in girls between the ages of 15 and 24 years. 28.4% of females under 25 years of age are infected. In 2005, 10,300 new cervical cancer cases were discovered and 3700 women died from the disease.

The picture is not as bleak as the foregoing paragraph implies. In 80% of females infected between the ages of 15 and 25 years and in 30% of those over 30 years old, the virus disappears. However, subtypes 16 and 18, which are responsible for 70% of cervical cancer cases, tend to be chronic. It is this chronic infection that predisposes women to cervical cancer. As well, prior experience with any subtype does not prevent re-infection upon re-exposure. Until now, the only way to deal with cervical cancer has been early detection by PAP smear. Unfortunately, although the incidence of cervical cancer has been dropping in the USA because of active implementation of this screening technique, 50% of women with cervical cancer never had a PAP smear! The situation is far worse in other countries where this screening is not practiced, causing the death rate from cervical cancer to be up to 50 times higher than it is in the US. In addition, PAP smears are often difficult to interpret, especially if a person is infected with a non-cancer causing subtype of HPV that can cause abnormal appearing cells in a PAP. Suspicious abnormalities lead to biopsy. Abnormal biopsies lead to a cone resection. Cone resections contribute to miscarriages and premature births. Clearly, a method to prevent HPV infection is preferable to a method of early screening that only discovers the problem after the fact.

Quadrivalent human papilloma virus vaccine (Gardasil®) was approved by the FDA in June 2006 for administration to girls aged 9 through 26 years old. This recombinant viral vaccine contains only the outer coat of the virus without any genetic material. It can not cause infection or disease. There is no preservative or antibiotic in the preparation. This vaccine contains subtypes 16 and 18, which are responsible for 70% of cervical cancers and subtypes 6 and 11, which are responsible for 90% of the cases of genital warts. After a single dose, cervical cancer from subtypes 16 and 18 is prevented in 97% of recipients and genital warts from subtypes 6 and 11 is prevented in 95%. After three doses on the recommended schedule these conditions are prevented in virtually 100% and 99% of recipients, respectively. For the best protection, the complete 3-dose schedule should be implemented. Immunity induced by natural infection is 10-30 times lower than that induced by the vaccine. This vaccine does not protect against other sexually transmitted disease, so condom protection is still required of those individuals who choose to be sexually active. The vaccine can not rid a person of HPV infection that is already present.

 

The currently recommended dosage schedule suggests that the first 2 doses be separated by 2 months or more (minimum 36 days) and the last dose be given 6 months (or more) after the first dose and at least 80 days after the second dose. There is no date after which the first doses expire. Duration of immunity is currently assessed at 4 years because that is how long the vaccine has been studied. Each year, the duration of immunity in the study population will be reassessed to determine if and when a booster dose will be recommended. Gardasil® may be administered simultaneously with hepatitis B vaccine and probably with other vaccines, as well.

Side effects of Gardasil® include local inflammation at the injection site (up to 10% greater incidence than placebo injection) and fever (up to 1.7% greater than placebo injection). Since sexually active individuals can acquire HPV before immunization is complete, and because other subtypes can cause cervical cancer, ongoing PAP smear surveillance is recommended. Testing for infection with HPV is currently only available on PAP smear material or rectal brushings. Blood tests are in development. Also undergoing research are recommendations for men and women who may already be infected with a different subtype of HPV.

In our view, a simple non-living vaccine that can prevent cancer in an important segment of the population is a wonder of modern science and is a welcome addition to the cache of vaccines we utilize to combat disease. We believe immunization against HPV does not promote sexual behaviors. If you have any questions, contact your child's physician.