The human papillomavirus vaccine Gardasil is not associated with an increase in pregnancy, sexually transmitted infections or contraceptive counseling, according to a study.
Since 2006, the U.S. Centers for Disease Control and Prevention has recommended that girls receive three doses of the vaccine at age 11 to protect them from HPV, which is transmitted through sexual activity and can cause genital warts and cervical, penile, vaginal and head and neck cancers. The vaccine also is recommended for females at age 13 if they did not receive the vaccine when they were younger, and for males at age 11.
By 2010, fewer than half of girls eligible for Gardasil had received even one dose. Since the introduction of Gardasil, concerns have arisen in peer-reviewed literature and in the media that use of the vaccine might lead to increased sexual activity, due in part to the mistaken belief that Gardasil protects against pregnancy and sexually transmitted diseases other than HPV.
The new study, an independent research project funded by Kaiser Permanente and Emory University, found no evidence to support those concerns.
“Our study found a very similar rate of testing, diagnosis and counseling among girls who received the vaccine and girls who did not,” Robert Bednarczyk, PhD, the studys lead author, said in a news release.
“We saw no increase in pregnancies, sexually transmitted infections or birth control counseling, all of which suggest the HPV vaccine does not have an impact on increased sexual activity,” added Bednarczyk, a clinical investigator with the Kaiser Permanente Center for Health Research-Southeast in Atlanta and an epidemiologist with the Rollins School of Public Health at Emory University.
The study included 1,398 11-year-old girls who were members of the Kaiser Permanente health plan in Georgia in 2006 and 2007, during the first 18 months after the Gardasil vaccine became available. Of this group, 493 girls received at least one dose of the HPV vaccine during the study period. The comparison group included 905 girls who received other recommended vaccines but not the HPV vaccine. Researchers followed both groups of girls for up to three years to assess whether they had been tested for or diagnosed with a sexually transmitted infection, had taken a pregnancy test or had been counseled about contraceptives.
About 10% of the girls in the study, both those who received the vaccine and those who did not, had one or more of these outcomes. The average age of testing, diagnosis or counseling was about 14.5. Only eight girls, or less than 1%, were diagnosed with an STI or had a positive pregnancy test. Girls who received the HPV vaccine did not have a statistically higher rate of testing, diagnosis or counseling compared to those who did not receive the vaccine.
“This is reassuring news for teenagers, parents and members of the public,” said Robert Davis, MD, MPH, a study co-author and senior investigator with the Kaiser Permanente Center for Health Research-Southeast. “Our study adds to growing evidence that the HPV vaccine is a safe and effective way to prevent these rare but sometimes deadly cancers.”
The study, which appeared Oct. 15 on the website of the journal Pediatrics, is part of Kaiser Permanentes ongoing research to understand the safety and efficacy of Gardasil. In another study, published earlier this month in the Archives of Pediatric and Adolescent Medicine, researchers confirmed the safety of the vaccine among nearly 200,000 young girls. Earlier this year in the Journal of Womens Health, researchers reported that younger girls are more likely than women to report pain and other non-serious side effects after receiving the Gardasil vaccine.
A PDF of the latest study is available at http://pediatrics.aappublications.org/content/early/2012/10/10/peds.2012-1516.abstract.