Gardasil is an investigational vaccine designed to prevent infection from four common human papillomavirus ( HPV ) types - 16, 18, 6 and 11 - and related cervical cancer, cervical pre-cancers and genital warts.
A study evaluated the immune responses and tolerability among young adolescents aged 10 to 15.
In this study, 1529 subjects were divided into three groups - 510 male 10- to 15-year olds, 506 female 10- to 15-year olds and 513 female 16- to 23-year olds - to compare the immune responses to Gardasil among the groups.
All subjects received three injections of Gardasil over a six-month period and were tested to see how well the investigational vaccine was able to stimulate specific immune responses against the four HPV types it contains.
Tolerability was also assessed.
The study evaluated immune system response using two measurements: seroconversion, or the development of HPV-specific antibodies in the blood that were not present prior to the administration of the vaccine, and GMTs ( geometric mean titers ), which indicate the level of anti-HPV antibodies in the blood.
Blood tests performed one month after the end of the study showed that seroconversion rates were 100 percent for HPV types 16, 6, and 11, and 99.9 percent for HPV 18 in the combined group of adolescents.
The corresponding numbers in 16- to 23-year-olds were 100, 100, 100, and 99.1 percent for HPV 16, 6, 11, and 18, respectively. Antibody levels, as measured by GMT, for all four HPV types were significantly higher in both adolescent girls and adolescent boys than in the 16- to 23-year-old group.
Administration of a three-dose regimen of Gardasil was generally well-tolerated in 10- to 15-year-old adolescents and in 16- to 23-year olds.
Only three adolescents ( 0.3 percent of adolescents in the study ) discontinued vaccination due to an adverse experience.
Fever within 15 days of administration of Gardasil was more common among 10- to 15-year olds compared to 16- to 23-year olds ( 13.3 percent vs. 7.3 percent, respectively ).
These differences were statistically significant ( p < 0.001 comparing 10- to 15-year-old male adolescents to 16- to 23-year-old young women and p = 0.004 comparing 10- to 15-year-old female adolescents to 16- to 23-year-old young women ).
However, fever episodes were generally short-lived and were not associated with serious clinical consequences.
It is estimated that approximately 20 million American men and women are infected with HPV.
In most people, HPV appears to go away on its own. In some, the virus has been linked to cervical cancer, abnormal Pap tests and genital warts.
Because males can become infected themselves and spread the virus unknowingly, they contribute to the risk of cervical cancer and are at risk of developing genital warts and, rarely, some cancers.
In the United States, an estimated 10,370 new cases of cervical cancer will be diagnosed in 2005, and there will be an estimated 3,710 deaths from cervical cancer.
Genital warts are common - 500,000 to 1,000,000 new cases per year in the United States alone - and treatment options may be painful
Source: 23rd Annual Meeting of the European Society of Pediatric Infectious Diseases ( ESPID ), 2005