Oct. 24 -- WEDNESDAY, Oct. 22 (HealthDay) -- Gardasil, the two-year-old vaccine that's designed to prevent cervical cancer, is safe, U.S. officials said Wednesday.
The U.S. Centers for Disease Control and Prevention's Immunization Safety Office said a study of 370,000 doses given to girls and young women over the past two years found no evidence that the vaccine causes an increased risk of blood clots or other serious conditions, Bloomberg News reported.
The CDC, which recommends the vaccine for girls starting at ages 11 and 12, based its findings on statistics from the Vaccine Safety Datalink, which uses medical data to test hypotheses about vaccine safety, the news service said.
"There were no associations found that suggested an elevated risk," said John Iskander, acting director for the Immunization Safety Office, told Bloomberg.
Critics of the vaccine, including some groups that worry that the inoculation could promote promiscuity, have contended that Gardasil may not be safe and could give women a false sense of security about sexually transmitted diseases.
Gardasil protects against four types of genital human papillomavirus, HPV, which is spread through sexual contact and can cause cervical cancer in women.
The U.S. study covered 190,000 girls and young women who received at least one dose of the vaccine's three-shot regimen. The CDC researchers compared medical data on those girls who got the vaccine with data for girls and young women who received other vaccines or none.
"The results are really reassuring," said Dr. Paul Offit, chief of the infectious diseases division at Children's Hospital of Philadelphia. "There's a public perception that the vaccine is not safe. This is important for countering negative information."
CDC officials had announced earlier this month that an estimated 25 percent of girls aged 11 to 17 have gotten the vaccine.
"This is very good for a first-year measurement of a new vaccine," Dr. Lance Rodewald, director of the Division of Immunization Services at the CDC' National Center for Immunization and Respiratory Diseases, said during a Oct. 9 teleconference announcing the survey. "It usually takes six to nine years to achieve the desired 90 percent coverage."
Rodewald noted that because the survey covered only young teens, many more young women have probably received the vaccine. The vaccine has been very well-tolerated, and its protection, especially when given at a younger age, is expected to last at least six years, he noted. Whether a booster shot will be needed isn't known yet.
The hope for the vaccine is that it will reduce the almost 4,000 cervical cancer deaths each year in the United States. Barriers to getting the vaccine include cost, which is about $375, although it is covered under many health insurance plans.
One side effect associated with the vaccine, fainting, resulted in the U.S. Food and Drug Administration last month requiring that vaccine manufacturer Merck & Co. add a warning to the package insert, advising doctors to watch patients for 15 minutes after the shot to be sure they don't faint.
In July, news stories said that almost 8,000 reports of adverse reactions to Gardasil -- including injection site pain and nausea -- had been filed with the CDC.
The reactions included 15 reports of death and 10 confirmed deaths, but none of the deaths has been tied to the vaccine, according to a CNN report.
After the CDC study results were released Wednesday, Merck issued the following statement: "Gardasil is an important tool to help prevent cervical cancer caused by HPV types 16 and 18 for girls and young women. About 30 women every day are diagnosed with cervical cancer in the United States. An estimated 8 out of 10 women will become infected with HPV in their lifetime. For most people, HPV clears on its own. But for some women who don't clear certain types of the virus, cervical cancer can develop. And there's no way to predict who will or won't clear the virus."
For more on Gardasil, visit the CDC.
SOURCES: U.S. Centers for Disease Control and Prevention, Atlanta; Bloomberg News; Oct. 22, 2008, news release, Merck & Co.