Lower prevalence of HPV infection in teen girls after vaccine introduction

Image: PD

1.  Within 4 years of vaccine introduction, the prevalence of vaccine-type HPV strains (6,11,16,18) decreased by 56% in girls ages 14-19. 

2. In the entire study population (women ages 14-59), the estimated vaccine effectiveness of at least 1 dose was 82% (95% CI, 53-93). 

Evidence Rating Level: 2 (Good) 

Study Rundown: This study found that 4 years after vaccine introduction, the prevalence of vaccine-type HPV strains (6, 11, 16, 18) decreased by 56% in a large, nationally representative sample of girls ages 14-19. Given that only 34% of participants in this age group reported receiving at least 1 HPV vaccine dose, these results suggest that the HPV vaccine is highly effective. Additionally, across all participants (women ages 14-59), the estimated vaccine effectiveness of at least 1 dose was 82% (95% CI, 53-93).

While the magnitude of the decrease is impressive, results may be limited by selection bias, particularly given the self-collection of specimens. Strengths include a nationally representative sample population and thorough evaluation of HPV infection by linear array. Further research might assess long-term immunity at 10 or even 20 years post-vaccination (stratified by receipt of 1 dose, 2 doses, or the complete 3-dose series), particularly given the rising age of first marriage in the U.S.

Click to read the study in the Journal of Infectious Diseases

Click to read an accompanying CDC Press Release

In-Depth [cross-sectional study]: Researchers from the CDC used data from the 2003-2010 National Health and Nutrition Examination Surveys (NHANES) to compare the prevalence of HPV infections in women ages 14-59 years in the pre-vaccine era (2003-2006) and the post-vaccine era (2007-2010). HPV infection was determined by analysis of self-collected cervicovaginal swab specimens.

A total of 4,150 participants from the 2003-2006 survey (83% of participants) and 4,253 participants from 2007-2010 (87% of participants) submitted adequate samples and were included in the analysis. In girls ages 14-19, the prevalence of HPV infection from any strain dropped 21% (PR=0.79, 95% CI=0.66-0.95) after vaccine introduction, falling from 32.9% pre-vaccine to 26.1% post-vaccine. In the same age group, the prevalence of vaccine type HPV (6, 11, 16, 18) decreased by 56%(PR=0.44, 0.31-0.62), from 11.5% to 5.1%. Across all age groups, the estimated vaccine effectiveness of at least 1 dose was 82% (95% CI, 53-93).

By Maren Shapiro and Leah Hawkins, MD, MPH

More from this author: USPSTF recommends chemoprevention for women at high risk for breast cancer, IUD contraception equally safe in teenagers as in older women, Black men less likely to receive follow-up for elevated prostate cancer marker, PSA,  More U.S. women using emergency contraception pill, No-cost contraception reduces unintended pregnancies 

© 2013 2minutemedicine.com. All rights reserved. No works may be reproduced without written consent from 2minutemedicine.com. Disclaimer: We present factual information directly from peer reviewed medical journals. No post should be construed as medical advice and is not intended as such by the authors or by 2minutemedicine.com. PLEASE SEE A HEALTHCARE PROVIDER IN YOUR AREA IF YOU SEEK MEDICAL ADVICE OF ANY SORT. Content is produced in accordance with fair use copyrights solely and strictly for the purpose of teaching, news and criticism. No benefit, monetary or otherwise, is realized by any participants or the owner of this domain.