[400] HPV Genotype Distribution in a Low-Risk Screening Population: Can the Impact of HPV Vaccination Be Demonstrated?

KK Dunning, RG Gamez, B Thyagarajan, K Savik, HE Gulbahce, K Kjeldahl, SE Pambuccian. University of Minnesota, Minneapolis, MN; University of Minnesota School of Nursing, Minneapolis, MN

Background: The first HPV vaccine, the tetravalent Gardasil® designed to protect against HPV 6, 11, 16, 18 was approved by the FDA on June 8 2006. The vaccine was originally indicated for use in women aged 9-26, but has also been shown to be beneficial in susceptible women aged 24-45. The aim of this study was to assess any changes in HPV genotype distribution before and after the introduction of HPV vaccination.
Design: All cases that had HPV genotyping performed by a PCR-based method using the MY09/11 consensus primers and typing by RFLP from 04/01/2001 to 12/31/2008 were retrieved together with the age of the woman and corresponding Pap test diagnosis. The frequency of HPV 6, 11, 16, 18 in tests performed before and after 07/01/2006 were compared (pre and post-vaccination cohorts). Age and Pap test diagnosis which may have a significant impact on HPV prevalence and genotypes were controlled for statistically.
Results: 24411 HPV tests were performed in this interval; 12866 in the pre-vaccination cohort and 11545 in the post-vaccination cohort. The mean age was higher in the post-vaccination cohort (35.6 vs 38.4 years, p<0.001). The majority of HPV tests were performed on women with ASC-US. Overall there was a significant reduction of the rate of HPV 6,11,16,18-positive cases detected in the post vaccination cohort.

Pre-VaccinationPost-Vaccinationp Value
Any HPV3904/12866, 30%3161/11545, 27%<0.001
HPV6307/3904, 8%183/3161, 6%0.001
HPV1160/3904, 1.5%35/3161, 1%0.12
HPV16905/3904, 23%571/3161, 18%<0.001
HPV18214/3904, 5.5%151/3161, 5%0.18

The differences in the HPV 6,11,16,18+ rate were significantly higher in the younger age groups, targeted by the vaccination.

The lower rate of HPV6,11,16,18 in the post-vaccination cohort persisted when controlling for age and Pap test diagnosis.
Conclusions: The significant decrease of the HPV types targeted by the tetravalent HPV vaccine in this study indicates the efficacy of the vaccination strategy.
Category: Cytopathology

Monday, March 22, 2010 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 47, Monday Morning


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