JONESBORO, AR (KAIT) - Cases of human papillomavirus (HPV) have decreased significantly since the vaccination became available in 2006, according to a new study from the Centers for Disease Control and Prevention.
The number of cases in 14 to 19-year-old females has declined by 56 percent, from 11.5 percent to 5.1 percent, a decrease doctors say was unexpected and a good sign.
"This report shows that HPV vaccine works well, and the report should be a wake-up call to our nation to protect the next generation by increasing HPV vaccination rates," said CDC Director Tom Frieden, M.D., M.P.H. "Unfortunately only one third of girls aged 13-17 have been fully vaccinated with HPV vaccine. Countries such as Rwanda have vaccinated more than 80 percent of their teen girls. 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 reach 80 percent vaccination rates. For every year we delay in doing so, another 4,400 girls will develop cervical cancer in their lifetimes."
Cervical cancer is caused by certain types of the common sexually transmitted virus called HPV, for human papillomavirus. The vaccine, which costs about $130 per dose, protects against a few of those strains, including two blamed for 70 percent of cervical cancers. The shots work best if given before someone is sexually active so the emphasis has been on giving the shots to 11- and 12-year olds.
Researchers compared the infection rates of 1,400 teen girls from 2003 through 2006, the pre-vaccine era, to the rates of 740 teen girls from 2007 through 2010, when doctors started using the vaccine.
Kristi Austin got her two sons who are now 12 and 15 years old vaccinated before they started junior high school.
"I know that it started out being mainly for girls, but when they started talking about it being for boys too, I wanted to protect my sons."
"A lot of the younger generation that's now coming to us has already been vaccinated," said Dr. Ashley Mitchell of OBGYN Associates of Jonesboro, Inc.
Mitchell says the numbers should ease concerns parents have with safety.
"As far as safety goes, I think we probably have more safety data on this than we do any of the rest of the childhood vaccines," she said. "We probably at this point have more research on this HPV vaccine and the safety and the efficacy before it even came out in '06, than we ever had for any of the rest of them."
Only about half of teen girls in the U.S. have gotten at least one dose of the expensive vaccine, and just a third of teen girls have had all three shots, according to the latest government figures.
ASU nursing professor Rebecca Matthews and her pediatrician husband David believe new parents should talk to their children about making good choices, but still get the vaccines.
"It's so rare to have a couple where neither one have had sex. In an ideal situation I would like that for my daughter, for my sons, but that is just not the case anymore," said Rebecca.
"The numbers on high school students are that 75 percent have already had sex by the time they finish high school. When I learned that number I became very apprehensive of not being more clear with parents that it was time to consider this cancer prevention vaccine a little heavier," said David. "Hormones make sex, not vaccines."
There are two vaccines against HPV, but the study mainly reflects the impact of Gardasil, the Merck & Co. vaccine that came on the market in 2006. A second vaccine approved in 2009 - GlaxoSmithKline's Cervarix - probably had relatively little bearing on the results, said the CDC's Dr. Lauri Markowitz, the study's lead author.
Both vaccines are approved for use in males and females - in ages 9 to 26 for females, and 9 to 21 in males. The vaccine was only recommended for boys in late 2011, and the CDC has not yet reported data on how many boys have gotten the shot since then. HPV vaccination requires three shots over 6 months.
An estimated 75 to 80 percent of men and women are infected with HPV during their lifetime. Most don't develop symptoms and clear it on their own. But some infections lead to genital warts, cervical cancer and other cancers. The study didn't look at cervical cancer rates. It can take many years for such cancers to develop, and not enough time has passed to know the vaccine's impact on cancer rates, CDC officials said.
The vaccine's impact was seen even though only 34 percent of the teens in the second group had received any vaccine. That could be due to "herd immunity" - when a population is protected from an infection because a large or important smaller group is immune.
Only about 20 percent of those vaccinated got all three doses. That result will likely feed an ongoing discussion about whether all three doses are necessary, Markowitz said.
Overall, the study found no significant change over time in the proportion of teens who'd ever had sex and in those who had multiple sex partners. However, it did find that a higher percentage of vaccinated teens said they'd had three or more sex partners.
That could have driven down infection rates, Markowitz noted, if the teens who got vaccinated were the ones at highest risk of getting an infection and spreading it.
The research was released online by the Journal of Infectious Diseases.
Click here to get information about HPV testing at the Craighead County Health Unit.