HPV vaccine reduces infection, even in unvaccinated

The HPV vaccine not only has resulted in a decrease in human papillomavirus infection in immunized teens but also in teens who were not immunized.

The study is believed to be the first to show a substantial decrease in HPV infection in a community setting as well as herd protection – a decrease in infection rates among unimmunized individuals that occurs when a critical mass of people in a community is immunized against a contagious disease.

The Cincinnati Children's Hospital Medical Center study will be published online July 9 in the eFirst pages of Pediatrics.

"Infection with the types of HPV targeted by the decreased in vaccinated by 69 percent," says Jessica Kahn, MD, MPH, a physician in the division of Adolescent Medicine at Cincinnati Children's and lead author of the study. "Two of these HPV types, HPV-16 and HPV-18, cause about 70 percent of cervical cancer. Thus, the results are promising in that they suggest that vaccine introduction could substantially reduce rates of cervical cancer in this community in the future."

The first HPV vaccine was licensed for use in the United States in June 2006. The U.S. Advisory Committee on Immunization Practices has recommended vaccination of girls and women between the ages of 11 and 26 to reduce rates of HPV infection, which ultimately can lead to cervical cancer.

In 2006 and 2007, Dr. Kahn and colleagues at Cincinnati Children's recruited 368 young women between the ages of 13 and 16 from two primary care clinics in the city of Cincinnati. The young women had sexual contact but none were vaccinated. In 2009 and 2010, they recruited a different group of 409 young women in the same age range, more than half of whom had received at least one dose of the vaccine. The researchers compared pre- and post-vaccination HPV prevalence rates.

The prevalence of vaccine-type HPV decreased 58 percent overall, from 31.7 percent to 13.4 percent. The decrease was high among vaccinated participants (69 percent), but also was substantial for those who were unvaccinated (49 percent).

Dr. Kahn says the decrease in vaccine-type HPV among vaccinated participants was "especially remarkable," given that participants were sexually experienced, many were exposed to vaccination-type HPV before vaccination, and only one dose of the vaccine was required to be considered vaccinated.

Dr. Kahn emphasizes that despite the evidence of herd immunity demonstrated in her study, vaccination of all young women between the ages of 11 and 26 is important to maximize the health benefits of vaccination.

Although vaccine-type HPV decreased, the overall prevalence of HPV (including types not targeted by the vaccine) in the study was "extremely high," says Dr. Kahn. "Nearly one in four unvaccinated study participants was already positive for at least one high-risk HPV type."

Most participants in the study were young, black women, many with Medicaid insurance. Given this, and the fact that the study was a relatively small one conducted in a single city, larger studies with more representative samples are needed to definitively determine the public health impact of the , says Dr. Kahn.

add to favorites email to friend print save as pdf

Related Stories

One in four California adolescent girls has had HPV vaccine

Feb 17, 2009

Less than two years after the HPV vaccine was approved as a routine vaccination for girls aged 11 and older, one-quarter of California adolescent girls have started the series of shots that protect against human papillomavirus, ...

Cervical disease sufferers could benefit from HPV vaccine

Mar 28, 2012

Women who are diagnosed with pre-cancerous cervical conditions after receiving the HPV vaccine can still benefit from a considerably reduced risk of reoccurring disease, a study published today in the British Medical Journal shows. ...

Recommended for you

Want kids to eat better? Get them cooking

Nov 27, 2014

(HealthDay)—Getting kids involved in the kitchen, through cooking classes or at home, may make them more likely to choose healthy foods, according to a recent review.

Life-saving promise in simple steps

Nov 27, 2014

The debate over the best time to clamp a baby's umbilical cord has been around forever. In about 350 BCE, Aristotle, reputedly the world's first genuine scientist, advocated delaying clamping until placenta ...

PCV13 recommended for 6- to 18-year-olds at high risk

Nov 26, 2014

(HealthDay)—Pneumococcal conjugate vaccine 13 (PCV13) should be administered to certain children aged 6 through 18 years who are at high risk of invasive pneumococcal disease (IPD), according to a policy ...

User comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.