The CDC (Centers for Disease Control and Prevention) has recommended that females aged 11 years be administered three doses of the vaccine to protect them from the human papillomavirus (HPV).
HPV is transmitted through sexual activity and is linked to a significantly higher incidence of genital warts, cervical cancer, as well as cancer of the head and neck, vagina and penis. This recommendation was issued in 2006.
The CDC also recommends that 13-year-old girls who have not yet been vaccinated be given the vaccine, as well as boys aged 11.
However, the uptake for the vaccine has been poor. By 2010, not even half of all the girls in the USA who were eligible received even one dose.
Worry about promiscuity partly to blame for the poor HPV vaccine uptakeSome concerns have been raised and published in both academic journals and other media. The main worry is that girls who are vaccinated may feel extra protected and will consequently become more sexually active. Another concern is that some girls might mistakenly believe that they cannot get pregnant or acquire any type of STI.
This new independent study, funded by Emory University and Kaiser Permanente, demonstrated that "there is no evidence to support these concerns".
Lead study author, Robert Bednarczyk, PhD, 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, said:
"Our study found a very similar rate of testing, diagnosis and counseling among girls who received the vaccine and girls who did not. 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."
Co-author Robert Davis, MD, MPH, said "This is reassuring news for teenagers, parents, and members of the public. 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 researchers gathered and examined data on 1,398 girls aged 11. They were all members of the Kaiser Permanente health plan in Georgia in 2006 and 2007 during the one-and-a-half years after the HPV vaccine, Gardasil, became available.
Of the 1,398 girls, 493 received at least one HPV vaccine dose during the study period. They compared the HPV vaccine girls with another group, involving 905 girls who did not receive the HPV vaccine. All the girls in both groups were followed for three years to determine whether they had been diagnosed or tested for an STI, had a pregnancy test, or had been counseled about contraceptives.
Approximately 10% of the girls in both groups had either became pregnant, took a pregnancy test, received contraception counseling, or were diagnosed or tested for an STI. The average age of girls with one or more of these outcomes was 14.5 years. Less than 1% of the girls, eight of them in total, received an STI diagnosis or became pregnant.
The girls in the HPV vaccine group had the same rates as those in the other group for STI testing and or diagnosis, counseling, or pregnancy.