Long-term effectiveness of HPV vaccination against HPV infection in young Japanese women: real-world data

Human papillomavirus vaccine to prevent CIN3 or worse (CIN3+): A nationwide case-control study in Japan

An increase in cervical cancer incidence has been reported in Japan. The Ministry of Health, Labor, and Welfare of Japan has resumed the active recommendation of regular HPV vaccines in 2022. In Japan, the preventive effect of CIN3+ in the real world has not yet been demonstrated in age-adjusted cohort or case-control studies. This study aimed to estimate the effect of the HPV vaccine against CIN3+ in Japanese women. This nationwide case-control study from April 2013 to March 2020 targeted women aged 20-26 years old at the time of cervical screening. We compared HPV vaccination exposure between those with abnormal and those with normal cytology. Abnormal cytology was classified into cervical intraepithelial neoplasia (CIN)1+, CIN2+, and CIN3+. We calculated the odds ratio (OR) and 95% confidence interval (CI) of the above endpoints and vaccination exposure using the conditional logistic regression model and estimated vaccine effectiveness using the formula (1 -OR) × 100. A total of 2790 cases and 13,990 controls (one-to-five matching) were eligible in 37 municipalities in Japan. In this study, 61 CIN3 (2.2%) and 10 squamous cell carcinomas (SCC) (0.4%) were found. The OR for CIN3+ versus controls was 0.14 (95% CI, 0.03-0.75), equating to a vaccine effectiveness of 86%. Of the 10 patients who had SCC none were vaccinated. This nationwide case-control study in Japan demonstrated a substantial risk reduction in CIN3+ among women who did versus those who did not receive HPV vaccination.

Human papillomavirus (HPV) vaccination in Japan

AIM

To review the status of human papillomavirus (HPV) vaccination in Japan from inception to the present, focusing on past and current challenges.

METHODS

Published articles and website content related to HPV vaccination were reviewed.

RESULTS

The Ministry of Health, Labor and Welfare suspended proactive recommendations for HPV vaccination in June 2013 following repeated media reports of girls experiencing adverse events, including chronic pain and walking disturbances, after receiving the HPV vaccine. Despite later recognition of these symptoms as a functional somatic syndrome, HPV vaccine coverage of target girls aged 12 to 16 years in the National Immunization Program (NIP) rapidly decreased to near zero. This suspension of the proactive HPV vaccination recommendation ceased in fiscal year (f-year) 2022, initiating a 3-year catch-up free HPV vaccination period from April 2022 to March 2025 for women born from f-years 1997 to 2005. These drastic changes were driven by established evidence of the effectiveness and safety of HPV vaccines reported from both Japan and other countries, and a nine-valent HPV vaccine has been included in the NIP since f-year 2023. However, the estimated HPV vaccination rate in the NIP remains low at ≤30%.

CONCLUSIONS

To regain high coverage of HPV vaccination in Japan, it is essential that government, industry, and academic society work together to raise awareness and educate Japanese people about cervical cancer prevention and HPV-related diseases.

Effectiveness of HPV vaccine against cervical precancer in Japan: multivariate analyses adjusted for sexual activity

Japanese girls aged 12–16 years are offered free human papillomavirus (HPV) vaccination and cervical cancer screening is conducted with cytology and not HPV testing from the age of 20 years. So far, no study has analyzed the effect of HPV vaccination against cervical precancers considering HPV infection status and sexual activity. We aimed to analyze the vaccine effectiveness (VE) against HPV infection and cytological abnormalities, adjusted for sexual activity. This study comprised women aged 20–26 years who underwent cervical screening in Niigata. We obtained HPV vaccination status from municipal records and a questionnaire along with information concerning sexual activity. Of 5194 women registered for this study, final analyses included 3167 women in the vaccinated group (2821 vaccinated women prior to sexual debut) and 1386 women in the unvaccinated group. HPV 16/18 (0.2% vs 3.5%), 31/45/52 (3.4% vs 6.6%), and 31/33/45/52/58 (5.0% vs 9.3%) positive rates were significantly lower in the vaccinated group (P < 0.001). No women vaccinated before sexual debut had HPV 16/18‐related cytological abnormalities. VE for HPV 16/18 infection and high‐grade cytological abnormalities in women vaccinated prior to sexual debut were 95.8% (95% CI 81.9–99.0%; P < 0.001) and 78.3% (95% CI 11.3–94.7%; P = 0.033), respectively, in multivariate analyses adjusted for age and number of sexual partners. However, analyses of all vaccinated women did not show significant effectiveness against cytological abnormalities. Our results showed the effectiveness of HPV vaccine against high‐grade cervical cytological abnormalities and the importance of the vaccination before sexual debut.

Long-Term Effects of Human Papillomavirus Vaccination in Clinical Trials and Real-World Data: A Systematic Review

The preventive effect of HPV vaccines against anogenital and oropharyngeal cancers has been proven in both clinical trials and real-world data. We reviewed the published evidence about the long-term efficacy and effectiveness of the HPV vaccine in available papers of clinical trials and real-world data. As far as we searched, the longest period of preventive effect for the bivalent, 4-valent, and 9-valent vaccine were 11 years in the Costa Rica trial, 14 years in the FUTURE II, and 8 years in the LTFU extension study of V503-002 and the Scandinavian study, respectively. The sustained clinical effect during the observation period was longest for the 4-valent vaccine. In real-world data, the longest observation period of the vaccine effectiveness was 12 years in an Australian study for the 4-valent vaccine. On the other hand, the longest period of long-term persistence of HPV vaccine-induced seropositivity was 14 years in FUTURE II for the 4-valent vaccine. For the bivalent vaccine, additional long-term follow-up studies may not have been planned due to the launch of the 4-valent and 9-valent vaccines. In some studies of the 9-valent vaccine, the results have not yet been published because of the short observation period. The additional results are expected in the future. In a national immunization program, most girls and boys are inoculated with HPV vaccine by the time puberty begins; thus, it is important to monitor the vaccine effect at least until the sexually active period in their 20s and 30s.