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

Investigating factors affecting the effectiveness of Gardasil 4, Cervarix, and Gardasil 9 vaccines considering the WHO regions in females: A systematic review

BACKGROUND

Currently, the best method for preventing Human Papilloma Virus (HPV) infection is vaccination. The present systematic review aims to review the latest findings on the factors affecting the efficacy of Gardasil 4, Cervarix, and Gardasil-9 vaccines on reducing pregenital lesions and reducing high-risk genotypes of cervical cancer in females aged 9-45 years and to examine the distribution of studies conducted in this regard in regions. In this study only the names of the vaccines were used and the vaccines were examined only according to the name. The name of WHO is only used to imply the distribution and access to health services in the world and not in terms of the vaccine approval in different organizations.

METHODS

A search for each vaccine was performed using PubMed, Scopus, and Web of Science. Five hundred and forty, 257, and 191 unique studies were obtained from the aforementioned databases for Gardasil 4, Cervarix, and Gardasil 9 vaccines, respectively. After applying the inclusion and exclusion criteria, 17 studies on Gardasil 4, seven studies on Cervarix, and two studies on Gardasil 9 were reviewed.

RESULTS

This study indicated that within various regions of the WHO, comprehensive effectiveness studies have not been conducted, and specifically within the Eastern Mediterranean Region (EMR) and South-East Asia Region (SEAR), no effectiveness studies have been recorded. Consequently, these regions necessitate the execution of effectiveness studies. Therefore, it is advisable to undertake investigations regarding the effectiveness of papillomavirus vaccination in the EMR and SEAR regions as delineated by the WHO. Moreover, it was demonstrated that in diverse nations, an array of factors such as age, gender, prevalent genotypes within the population, culture, the age at sexual activity initiation, the healthcare infrastructure, and timely screening can significantly impact the effectiveness of the vaccine. Furthermore, in nations with suboptimal vaccination coverage, a robust healthcare system coupled with the implementation of specialized testing and prompt follow-up can substantially aid in cancer prevention. The outcomes of this investigation confirm the administration of at least one dose of the vaccination. It reveals that in the absence of vaccination, a stringent healthcare system may contribute to the reduction of cervical cancer incidence. Additionally, in these nations, enhancements in healthcare systems, screening protocols, and public awareness play a crucial role in augmenting vaccination effectiveness. Collectively, a lower age at the time of vaccination (9-15 years), reduced sexual exposure prior to vaccination, vaccination prior to the onset of precancerous lesions, and adherence to the recommended vaccination schedule are associated with heightened vaccine effectiveness. Furthermore, the effectiveness of the vaccination dose is age-dependent, as one dose can be effective for individuals aged 15 years or younger.

CONCLUSIONS

Various factors, including age, sex, common genotypes in population, culture, age at sexual initiation, healthcare system, and screening at recommended time, can play a significant role in vaccine effectiveness. Additionally, it is suggested that in the developing countries, a single dose vaccination program is sufficient for children aged 15 years or younger. Also in these countries, improving the care system, screening system, and awareness play a significant role in enhancing the effectiveness of vaccination. It is also recommended that studies on the effectiveness of the papilloma vaccination in the EMR and SEAR regions covered by the WHO to be conducted. According to the inclusion criteria, all countries were included in the study; thus, the effects of the individual's genotype, which depends on the geographical region, can affect the vaccine effectiveness. Individuals aged 9-45 who can receive the vaccine according to the guidelines, were included in the study. Age is one of the factors affecting the vaccine effectiveness. Also, according to the policies of healthcare organizations, including the Ministries of Health of countries, various health services are provided in different geographical regions. Therefore, females's access to the vaccine occurs at different ages, and the effectiveness of the vaccine decreases by increasing the age at which the vaccine is received. Countries with poor healthcare system have less access to the vaccine, which can affect the effectiveness of the vaccine and herd immunity.

Prevalence of non-vaccine high-risk HPV cervical infections in vaccinated women: a systematic review and meta-analysis

BACKGROUND

Human Papillomavirus (HPV) is the most common sexually transmitted lower genital tract infection worldwide and the main etiological factor of cervical cancer (CC). Since 2006, vaccines have been implemented to reduce CC-related morbidity and mortality. This systematic review and meta-analysis aimed to evaluate the prevalence of cervical infections by non-vaccine high-risk HPV (HR-HPV) types in women vaccinated against types 16 and 18.

METHOD

This systematic review and meta-analysis used independent electronic databases - Lilacs, WHO, BDENF, State Department of Health SP, Health Information Locator, IRIS, Coleciona Sistema Único de Saúde, BINACIS, IBECS, CUMED and SciELO, on July 14, 2023. Observational studies that evaluated vaccinated and unvaccinated women against HR-HPV and the prevalence of cervical infection by types of HR-HPV were included. Intervention effects were expressed as prevalence ratios (PR). Forest plots were used to visualize vaccination effects. The study protocol was previously registered in PROSPERO, under code CRD42023440610.

RESULTS

Of the 7,051 studies, 31 met the analysis criteria. A total of 59,035 women were eligible for this systematic review. The results showed a high prevalence of non-vaccine HR-HPV types, regardless of vaccination status. For HPV 31/33/45 (PR = 0.60 [0.40-0.91]), HPV31 (PR = 0.47 [0.31-0.72]), and HPV 45 (PR = 0.38 [0.22-0.69]), a positive random effect was found.

CONCLUSION

The prevalence of non-vaccine HR-HPV cervical infection was high in women, regardless of vaccination status. For HPV types 31 and 45 and 31/33/45, the prevalence was lower in vaccinated women, suggesting a cross-protective effect of vaccines for these viral types.

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.

Awareness regarding human papillomavirus and willingness for vaccination among college students with or without medical background in Guizhou Province

This cross-sectional epidemiological study aimed to investigate awareness regarding human papillomavirus (HPV) and willingness for vaccination among college students with or without medical background in Guizhou Province, China. A logistic regression model was used for univariate and multivariate analyses of cognition to determine factors influencing willingness for vaccination. In total, 2,540 questionnaires were collected, of which 2,360 were valid. The medical and nonmedical groups included 737 (31.2%) and 1,623 (68.8%) individuals, respectively. The medical group had heard of HPV and its vaccines more frequently than the nonmedical group, with the former also having greater awareness than the latter (P < .001). Females (1,325, 56.1%) had heard of HPV and its vaccines more frequently than males (1,035, 43.9%), with the former also having greater awareness than the latter. The cost, safety, and efficacy of the HPV vaccine and lack of knowledge regarding HPV and its vaccines were the main barriers for vaccination. The overall level of knowledge regarding HPV and its vaccines was lower in the nonmedical group and males than in the medical group and females. To help promote willingness for vaccination among the nonmedical group and males, strategies that deepen their knowledge regarding the HPV vaccine are needed.

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.