Influence of Pre-Vaccination HPV Status on Vaccine Effectiveness Among Chinese Women: A Multicenter Cross-Sectional Study.

Background And Aims: Human papillomavirus (HPV) vaccines have been available in China for only 8 years, and routine HPV testing is not recommended prior to vaccination. Therefore, evaluation of HPV vaccine effectiveness and the impact of pre-vaccination HPV infection status on vaccine protective effect in Chinese women is warranted.

Methods: From June 2022 to June 2023, women aged 18 to 50 years without a history of cervical or uterine excision were recruited from three medical institutions. Baseline characteristics were compared between vaccinated and unvaccinated participants, with inverse probability treatment weighting (IPTW) applied to adjust for confounding factors. HPV infection rates and vaccine effectiveness (VE) were calculated. Additionally, a sub-group analysis was conducted among vaccinated women to explore the impact of pre-vaccination HPV infection status.

Results: After adjusting for group differences, the vaccine effectiveness against new HPV16/18 infections was 76.1% (95% CI: 58.7%-86.2%) among 2285 participants. Older age and possession of a master's degree or higher were identified as protective factors, whereas increased parity and exclusive use of oral contraceptives were determined to be risk factors for HPV16/18 infection. Women with unknown pre-vaccination HPV status exhibited significantly higher post-vaccination rates of high-risk HPV infections (RR 4.278, 95% CI: 2.537-7.215) compared to those who were HPV-negative prior to vaccination. However, no significant difference in new high-risk HPV infection rates was observed between pre-vaccination HPV-negative and HPV-positive women.

Conclusion: In addition to HPV vaccination, factors such as age, parity, exclusive use of oral contraceptives, and higher education attainment were independently associated with HPV16/18 infection rates. Pre-vaccination HPV infection status did not significantly influence the protective efficacy of the HPV vaccine against previously unencountered HPV types.