[Evaluation of the 10-year protective effect and immunogenicity of quadrivalent HPV vaccination].

<b>Objective:</b> To evaluate the 10-year protective effect and immunogenicity of quadrivalent human papillomavirus (HPV) vaccine in Chinese women aged 20 to 45 years. <b>Methods:</b> From October 2019 to April 2020, a long-term follow-up study was conducted on the subjects of the Phase III clinical trial of the quadrivalent HPV vaccine (NCT00834106). Participants underwent a questionnaire survey, venous blood sampling, gynecological examination, cervical exfoliated cell pathology examination, and serum neutralizing antibody titers for HPV-6, 11, 16, and 18 were measured using a pseudovirus neutralization assay. The results of the cytological examination and the positive rate and titers of serum antibodies of different cervical exfoliated cells were compared. <b>Results:</b> A total of 889 subjects were followed up, including 240 in the control group, 453 in the vaccination group and 196 in the post-trial vaccination group. The age of the control group was (40±7) years old, which was higher than that of the supplementary vaccination group and the vaccination group [(38±4) and (38±6) years old, respectively] (<i>P</i><0.05). There were no statistically significant differences in condom use and sexual frequency among all groups (all <i>P</i> values>0.05). The abnormal proportion of cervical exfoliation cytopathology in the vaccination group was 3.7% (17/453), which was significantly lower than that in the control group [9.6% (23/240)] and post-trial vaccination group [5.6% (11/196)] (<i>P</i><0.05). There were two cases of cervical intraepithelial neoplasia (CIN) grade 1 in the vaccination group, two cases of CIN grade 1 and three cases of CIN grade 2 and above in the control group, and no CIN grade 1 and above cases in the post-trial vaccination group. The positive rate of HPV-18 antibody was 35.5% (161/453) in the vaccination group and 76.0% (149/196) in the post-trial vaccination group, which was significantly lower than that of other types (<i>P</i><0.05). The neutralizing antibody GMT ratio between the vaccination group and the control group ranged from 2.62 to 25.33 (9.05 to 83.08). <b>Conclusion:</b> Protective neutralizing antibodies are sustained in Chinese women aged 20 to 45 years after ten years of vaccination with quadrivalent HPV vaccine.