Lower HPV Rates in Teen Girls Attributed to VaccineJun 20, 2013
Researchers from the Centers for Disease Control and Prevention (CDC) are reporting a 56% drop in human papillomavirus (HPV) infections in girls and young women since the HPV vaccine was introduced in the US. This large reduction in HPV occurred even though vaccination rates in the US are very low. Only one-third of girls ages 13 – 17 in the US have received all 3 doses, as recommended.
“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, MD, MPH in a statement. “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% of their teen girls.”
Frieden said the low US vaccination rates mean 50,000 girls alive today will, during their lifetime, develop cervical cancer that could have been prevented.
Infection with certain types of HPV – a group of many different viruses – is the main risk factor for cervical cancer and pre-cancer and for genital warts. There are 2 vaccines against HPV approved for use in the US: Cervarix protects against 2 types of HPV strongly linked to cervical cancer; Gardasil protects against those same 2 types, plus 2 others known to cause most cases of genital warts.
To be effective, though, either vaccine should be given before a person becomes exposed to HPV, which usually happens through sexual activity. The American Cancer Society recommends the 3-dose vaccine for girls ages 11 to 18.
The CDC study about the effectiveness of the vaccine was published June 19, 2013 in The Journal of Infectious Diseases. Researchers used the National Health and Nutrition Examination Survey (NHANES) data to compare the prevalence of HPV among girls and women before and after the vaccine was available. They found that within 4 years after the vaccine was available, prevalence of the type of HPV targeted by the vaccine decreased among girls and women ages 14 – 19.
Why US vaccination rates are low
Debbie Saslow, PhD, director of breast and gynecologic cancers at the American Cancer Society, said she welcomes the results of the study, and is not surprised by the results. “It was expected that HPV prevalence would decrease substantially given how effective the HPV vaccines were in clinical trials, and given the impact we have seen in Australia and other countries where most adolescent girls are vaccinated.”
Saslow said that while she hopes these and other similar studies will lead to more girls getting the vaccine, the most common reason that girls don’t get it is because their doctor does not recommend it.
“Often the health provider doesn't consider the vaccine as important as other vaccines, such as those that are required for school attendance,” Saslow said.
Because HPV is sexually transmitted, she said, providers and parents may also be uncomfortable discussing it with young people. And some parents may not think it’s necessary to vaccinate their children because they don’t think their children are sexually active.
The vaccines are recommended for girls ages 11 to 12 because most girls at this age have not become sexually active. The vaccines will prevent the covered types of HPV only if they are given before exposure to the virus. This is also an age when girls still will be seeing their doctor regularly and getting other vaccinations.
Read more about the HPV vaccine for girls in Saslow’s Expert Voices blog.
Reduction in Human Papillomavirus (HPV) Prevalence Among Young Women Following HPV Vaccine Introduction in the United States, National Health and Nutrition Examination Surveys, 2003–2010. Published June 19, 2013 in The Journal of Infectious Diseases. First author Lauri E. Markowitz, MD, Centers for Disease Control and Prevention, Atlanta.