HPV Vaccine Lowering Infection Rates Among Girls
Extent of protection from sexually transmitted virus higher than expected, suggesting 'herd immunity' is at work, experts say
WebMD News Archive
The study was based on data from the CDC's National Health and Nutrition Examination Survey. It compared HPV infections in teenage girls from 2003 to 2006 (before the start of the United States' HPV vaccination program) against infections that occurred from 2007 to 2010, after girls began receiving the vaccine.
The CDC team showed that infections by the HPV types covered by the vaccine fell dramatically -- from 11.5 percent in the pre-vaccine era to 5.1 percent post-vaccine.
There has been some public resistance to the HPV vaccine, of which there are now two versions, Gardasil (approved in 2006) and Cervarix (approved in 2009). The CDC currently recommends routine immunization at ages 11 to 12 for both boys and girls -- before most young people become sexually active.
A series of three shots is recommended over six months for both girls and boys. HPV vaccination is also recommended for older teens and young adults who were not vaccinated when younger.
"Unfortunately, only one-third of [U.S.] girls aged 13 to 17 have received the full three-dose series of the HPV vaccine," Frieden pointed out. In contrast, "countries such as Rwanda have vaccinated more than 80 percent of their teen girls. [The U.S. rate] is simply unacceptable. Our low vaccination rates represent 50,000 preventable tragedies; 50,000 girls alive today will develop cervical cancer over their lifetime that would have been prevented if we had reached our goal of 80 percent vaccination rates. For every year we delay in doing so, another 4,400 girls will develop cervical cancer in their lifetimes."
Brooks believes resistance to vaccination stems from a couple of factors, one being the difficulty in explaining to people how the vaccine works. "It's a conceptually difficult thing for people to recognize -- that a virus causes a cancer," he said. "That's a major, major issue."
Parents also have been reluctant to have their adolescent girls and boys receive a vaccine against a sexually transmitted disease, said Dr. Jill Rabin, head of urogynecology at Long Island Jewish Medical Center in New Hyde Park, N.Y.
"This is the tack that I take with patients and with families: the reason we give it to younger women is that they will build up the best antibody response," Rabin said. "It's not that we're giving it now because we expect them to have sex in their teenage years. We're giving it because they will make the best antibody response so when they do become sexually active, they will have protection at that point.
"If you give it to a 26 year old, they aren't going to mount as good an antibody response as someone who is 11 or 12 years old," she continued. "You're going to be giving better protection if you give it younger. It's not permission for them to go out and have intercourse."