The human papillomavirus, commonly referred to as HPV, is the most common sexually transmitted infection in the United States and has been linked to a host of illnesses from cancer to genital warts. The Food and Drug Administration has now approved two vaccines for protection from HPV.
The FDA gave Gardasil a green light in October 2009 to be the first such product to be administered to males between the ages of 9 and 26 for the prevention of genital warts (condyloma acuminata) due to HPV types 6 and 11. It also granted a license for Cervarix for use in women and girls to prevent cervical cancer and precancerous lesions caused by HPV types 16 and 18.
Gardasil, manufactured by Merck and Company Inc. of Whitehouse Station, N.J., was first approved by the FDA in 2006 for girls and women, ages 9 to 26 for the prevention of cervical, vulvar and vaginal cancer caused by HPV types 16 and 18; precancerous lesions caused by types 6, 11, 16, and 18; and genital warts caused by types 6 and 11. The company is currently seeking FDA approval for use in older women.
HPV types 16 and 18 cause about 70 percent of cervical cancers worldwide. An estimated 11,270 new cases and 4,070 deaths from cervical cancer occurred in the United States in 2009, according to the National Cancer Institute at the National Institutes of Health.
“Gardasil is the first preventive therapy against genital warts in boys and men ages 9 through 26, and, as a result, fewer men will need to undergo treatment for genital warts,” said Karen Midthun, M.D., acting director of the FDA’s Center for Biologics Evaluation and Research.
Gardasil is given as three injections over a 6-month period. Headache, fever and pain at the injection site, itching, redness, swelling and bruising, were the most common side effects observed during clinical trials.
For men and boys, Gardasil’s effectiveness was studied in a randomized trial of 4,055 males ages 16 through 26-years-old. The results showed that in men who were not infected by HPV types 6 and 11 at the start of the study, the vaccine was nearly 90 percent effective in preventing genital warts caused by infection with HPV types 6 and 11.
Studies were conducted to measure the immune response to the vaccine in boys ages 9 through 15. The results showed that the immune response was as good as that found in the 16 through 26 years age group, indicating that the vaccine should have similar effectiveness.
The manufacturer has said it will conduct postmarketing studies to obtain additional information on the safety and effectiveness of Gardasil in boys and men.
In October 2009, the FDA also gave approval for a new vaccine to prevent cervical cancer and precancerous lesions caused by HPV types 16 and 18 when it licensed Cervarix for use in girls and women ages 10 years through 25 years. Cervarix is manufactured by GlaxoSmithKline Biologicals, in the United Kingdom.
“The licensure of Cervarix adds another option in the prevention of cervical cancer” Dr. Midthun, said. “It has the potential to save lives from cervical cancer as well as reduce the need for biopsies and invasive procedures associated with the necessary follow-up from abnormal Pap tests.”
The primary clinical study for Cervarix included more than 18,000 women ages 15 years through 25 years in the United States and 11 other countries. Of these women, about 9,000 received Cervarix and 9,000 received Havrix, a licensed hepatitis A virus vaccine, as a control.
Results showed that among females who had not already been infected by HPV types 16 and 18 before the start of the study, Cervarix was about 93 percent effective in preventing precancerous cervical lesions caused by these HPV types.
Among all study participants vaccinated with Cerarix—some who tested negative and others who tested positive for these HPV types—showed the vaccine was about 53 percent effective in preventing cervical cancer lesions.
Studies also measured the immune response to Cervarix in girls, ages 10 through 14 years, which indicated a similar effectiveness found in the 15- to 25-year-old group. Current data show the vaccine provides protection for about 6.4 years, however additional information on the length of protection is forthcoming.
The Centers for Disease Control (CDC) points out that no vaccine is 100 percent effective, and Cervarix does not protect against HPV infections that an individual may already have at the time of vaccination. Nor does it necessarily protect against additional HPV types not in the vaccine. Therefore, the CDC recommends regular Pap tests should be continued for all women who receive Cervarix. Pap screening remains critically important to detect precancerous changes, which would allow treatment before cancer develops.
Like Gardisil, Cervarix is administered in three separate shots, with the initial dose being followed by two additional shots at one and six months.
No doubt these vaccines can raise numerous questions about safety and efficacy for many people. For more information, check out these helpful websites:
Gardasil product information:
CDC Questions and Answers about HVP Vaccine Safety:
Lynette Summerill, is an award-winning journalist who lives in Scottsdale, Arizona. In addition to writing about cancer-related issues, she writes a blog, Nonsmoking Nation, which follows global tobacco news and events.