HPV vaccination status and effectiveness in Korean women with HPV16/18 infection (2010-2021): a retrospective study.

OBJECTIVE:To evaluate human papillomavirus (HPV) vaccine effectiveness in a cohort of Korean women infected with HPV. METHODS:From 2010 to 2021, Korean women aged 20-60 years who diagnosed HPV-positive atypical squamous cells of undetermined significance or low-grade squamous intraepithelial lesion were recruited from 6 hospitals. HPV vaccine effectiveness was estimated by observing the differences in pathological and clinical information and experimental results-prevalence, viral load (VL), physical state (PS), and HPV16/18 infection duration-between the vaccinated and unvaccinated groups. RESULTS:HPV16/18 prevalence declined from 18.5% to 11.8% as vaccination rates increased from 14.3% to 60.7% in the 1,757 registered cohort women. DNA analysis from 96 samples collected from the participants, indicated that HPV vaccination reduced HPV16 VL by 6 times and increased E2/E6 ratio for both HPV16 and HPV18 by 1.4 and 5 times, respectively. The HPV16 infection rate-lasting more than 18 months from 31.0% to 21.6%-and the HPV18 infection rate-lasting more than 12 and less than 24 months from 35.5% to 21.1%-were reduced by vaccination. We found VL and the infection duration to be directly proportional. Moreover, HPV vaccination reduced not only the VL to 1/4 in both the persistence and clearance groups but also the persistence rate from 90% (27/30) to 70.6% (12/17) in HPV16. CONCLUSION:HPV vaccination reduced the prevalence and duration of infection and kept the PS in an episomal form for both HPV16 and HPV18. The tendency of persistence VL to be higher than clearance in the unvaccinated group implies that the vaccine's effect of reducing VL in HPV16 may lower the risk of progression to cervical cancer by shortening the infection duration.