The human papillomavirus (HPV) vaccine is producing remarkable results in teenage girls by cutting infections in half. A new study measures the vaccines impact since it came on the market in 2006.
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.
"These are striking results and I think they should be a wake-up call that we need to increase vaccination rates," said Dr. Thomas Frieden, director of the Centers for Disease Control and Prevention.
The CDC study compared infection rates in girls 14 to 19 before and after the vaccine became available. The proportion infected with the targeted HPV strains dropped 56 percent, from about 12 percent before the vaccine was sold to 5 percent. That result was for all teens after it was on the market, whether or not they were vaccinated.
Among girls who had gotten the vaccine, the drop in HPV infections was higher " 88 percent.
For the vaccine to be effective, 3 shots have to be given over a period of 6 months. There are two vaccines against HPV, but the study only looked at Gardasil. Both vaccines are approved for use in males and females " ages 9 to 26 for females and ages 9 to 21 in males.
The study involved interviews and physical examinations of nearly 1,400 teen girls in 2003 through 2006 and of 740 girls in 2007 through 2010.
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.
Some parents have balked at having their children and teens vaccinated for a sexually transmitted disease out of concern that it could encourage sexual activity. Frieden said the vaccination is meant to protect them when they become adul