[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-Vaccination | Post-Vaccination | p Value | |
| Any HPV | 3904/12866, 30% | 3161/11545, 27% | <0.001 |
| HPV6 | 307/3904, 8% | 183/3161, 6% | 0.001 |
| HPV11 | 60/3904, 1.5% | 35/3161, 1% | 0.12 |
| HPV16 | 905/3904, 23% | 571/3161, 18% | <0.001 |
| HPV18 | 214/3904, 5.5% | 151/3161, 5% | 0.18 |
