Estimation of self-funded human papillomavirus vaccine recipients from Japan's previously assumed "unvaccinated generation".

Precise vaccination data is essential to accurately estimate the effectiveness of the human papillomavirus (HPV) vaccine against HPV-related cancers. In Japan, the number of subsidized HPV vaccinations can be tracked through registries, but the number of self-funded vaccinations has not been tracked. The number of individuals who chose to receive the vaccine at their own expense, despite being ineligible for public subsidies due to their age, is unknown and has been nominally considered to be zero. Our aim is to produce a more accurate estimate of this number using recently released proprietary data. First, we estimated the total number of self-funded HPV vaccinations occurring from 2010 to 2012 using public data from the Ministry of Health, Labour and Welfare and our previously reported data on the number of HPV vaccinations eligible for public subsidy. Second, using proprietary data from the vaccine manufacturer, we calculated the distribution of self-funded vaccination shots by age. Finally, we combined these data to estimate the number of self-funded HPV vaccinations by birth fiscal year (FY) relative to a yearly reference population. We found that 78,264 individuals born in FY1993 and 58,190 born in FY1992 self-funded their vaccinations, representing 13.6% and 10.0% of the reference population, respectively. Additionally, we found that 5%-10% of individuals born from FY1986 to FY1991 self-funded their vaccinations. Our study revealed for the first time that a certain number of individuals from the "HPV unvaccinated generation," ineligible for subsidies due to age restrictions, chose to self-fund their vaccinations.

Human Papillomavirus Vaccination by Birth Fiscal Year in Japan.

Importance: The Ministry of Health, Labour, and Welfare (MHLW) of Japan aggregates human papillomavirus (HPV) vaccination data across Japan for each fiscal year (FY) by age at vaccination. Birth FY (BFY)-specific vaccination coverage remains unknown. Objective: To calculate the BFY-specific vaccination coverage for each FY and the cumulative first-dose coverage for each BFY in Japan, to understand the generation-specific vaccination coverage, and to estimate the cumulative first-dose coverage of each BFY that would be achieved by FY 2028 vs World Health Organization (WHO) targets. Design, Setting, and Participants: In this cross-sectional study, MHLW-published national age-specific HPV vaccination numbers and demographic data for female individuals were used to calculate the BFY-specific first-dose coverage for each FY and the BFY-specific cumulative first-dose coverage. It was assumed that the BFYs 2007 to 2012 vaccination coverage in FY 2023 to 2028 would remain the same as the vaccination coverage of the same grade in FY 2022 to estimate the cumulative first-dose coverage that would be achieved by FY 2028. Data analysis was performed from December 2023 to January 2024. Exposure: Two MHLW policy changes were the government's suspension of proactive recommendation for HPV vaccination in June 2013 and the government's resumption of proactive recommendation for HPV vaccination in April 2022. Main Outcomes and Measures: The primary outcome was generation-specific vaccination coverage among female individuals born in BFYs 1994 to 2010 in FYs 2010 to 2022, calculated using reconfigured published data. Results: In this study of vaccination data for 9 414 620 female individuals, the generation-specific vaccination coverage was 71.96% for the vaccination generation (BFYs 1994-1999), 4.62% for the vaccine-suspension generation (BFYs 2000-2003), 16.16% for the generation that received information individually (BFYs 2004-2009), and 2.83% for the vaccine-resumed generation (BFY 2010). HPV routine vaccination coverage was extremely low in BFYs 2000 to 2010 (0.84%-25.21%) vs BFYs 1994 to 1999 (53.31%-79.47%). The cumulative first-dose coverage that was estimated to be achieved in the vaccine-resumed generation by FY 2028 plateaued at 43.16%. Conclusions and Relevance: Even after the resumption of MHLW's proactive recommendations, HPV vaccination coverage has only minimally recovered in Japan. The cumulative first-dose coverage that was estimated to be achieved in the vaccine-resumed generation by FY 2028 is below the WHO target. These findings reveal that stronger cervical cancer control measures are required, particularly for the vaccine-resumed generation, which will plateau at approximately one-half the WHO target values.

Even though active recommendation for HPV vaccination has restarted, Japan's rates have not recovered.

Japan has a particularly critical situation surrounding its collapsed HPV vaccination program for preventing HPV-caused cervical cancers, a problem exacerbated by the lack of a national immunization database. We have determined the year-to-year HPV vaccination uptake by Japanese females and analyzed by birth fiscal year (FY) the monthly number of people receiving initial HPV vaccination. Our analysis covers the period from the start of public subsidies in 2010 to September 2023, using data provided by local governments. We calculated the cumulative number of monthly immunizations for those unimmunized as of April (the beginning of each vaccination year). The monthly number of initial HPV vaccinations was highest in August for every FY from FY 2010 to FY 2023; a second vaccination peak tended to occur in March when the vaccination year ended. The highest number of August vaccinations occurred in FY 2011, followed (in order) by 2012, 2021, 2022, 2023, and 2013. In Japan's ongoing catch-up vaccination program for young women, the monthly number of vaccinations increased in August 2022 but then slowed the following year. After FY 2021, the cumulative vaccination coverage of subjects unvaccinated at the beginning of the vaccination year but subsequently covered by routine immunizations was slightly improved. FY 2021 was when the governmental recommendations for HPV vaccination were resumed. More recent vaccination rates are considerably lower than those in FY 2011-2012 when vaccinations were first fully endorsed. Paralyzing HPV vaccination hesitancy, which began in FY 2013, will linger in Japan in FY 2024.

HPV Vaccine Issues in Japan: A review of our attempts to promote the HPV vaccine and to provide effective evaluation of the problem through social-medical and behavioral-economic perspectives.

In Japan, subsidies from local and national government programs for HPV vaccination of girls aged 13-16 began in 2010. By 2013, HPV vaccines were being used routinely for vaccinating girls aged 12-16 as part of its national immunization program. However, in June of 2013, in response to reports of possible adverse reactions to the vaccine, Japan's Ministry of Health, Labor, and Welfare (MHLW) announced a 'temporary suspension' of its governmental recommendation for HPV vaccination. The vaccination rate quickly dropped from 70 % of age-eligible girls to almost zero. It was not until 2021 that the government's recommendation suspension finally ended. The efficacy and safety of the HPV vaccine is now well documented, yet Japan has failed to reestablish any credible level of HPV vaccination. The World Health Organization (WHO) warned that Japan's HPV vaccination debacle was likely to result in real harm to the girls who lacked its protection; something we have already demonstrated with real-world data. To reinvigorate the HPV vaccination program in Japan to its prior levels, in the face of the current high level of HPV vaccine hesitancy, we will have to address the irrationality of human decision-making pointed out by behavioral economics. The Japanese government must act expeditiously to promote stronger cervical cancer control measures.

Parental gender influences their intention to HPV vaccinate their children, and the association between HPV and COVID-19 vaccination intentions.

Purpose: The coronavirus disease of 2019 (COVID-19) pandemic has increased public awareness of infectious diseases and interest in vaccines, including the human papilloma virus (HPV) vaccine. We investigated differences between parental gender and intentions to vaccinate their child for HPV and COVID-19. Methods: We analyzed data from Japan's COVID-19 and Society Internet Survey (JACSIS), a web-based cross-sectional survey of 2,444 respondents in 2021. Results: Females were more knowledgeable and more afraid of HPV and COVID-19 than males. The proportions of females in favor of, or against, HPV vaccination was higher than among males. The fathers' intention for HPV vaccination was significantly associated with the child's gender, knowledge regarding HPV, and intention to inoculate with the COVID-19 vaccine. The mothers' intention was also associated with her knowledge of HPV and her intention to seek the COVID-19 vaccine, but it included a greater fear of HPV infection. Both male and female parents favored the COVID-19 vaccine over the HPV vaccine. Parents approving of COVID-19 vaccination believed in the overall efficacy of vaccines and were more receptive to opinions from the administration and physicians, even if the parent was currently against HPV vaccination. Conclusions: Mothers were more knowledgeable about HPV and more favorable to vaccinate their child for HPV than fathers. The intention to have children COVID-19 vaccinated was also higher than for HPV vaccination. During this period of heightened public interest in vaccines due to the COVID-19 pandemic, this is a good time to educate and inform the public about HPV.

Effectiveness of catch-up and routine program of the 9-valent vaccine on cervical cancer risk reduction in Japan.

In 2013, the national human papillomavirus (HPV) immunization program began. However, in June 2013, Japan's Ministry of Health, Labor and Welfare (MHLW) announced a "temporary" suspension of its recommendation for the human papillomavirus vaccine. Finally, in November 2021, the MHLW ended its suspension of the recommendation of the HPV vaccine. To address the 9-year gap in HPV vaccinations the suspension had caused, the MHLW conducted a program of catch-up vaccinations from April 2022 to March 2025. Finally, in April 2023, the 9-valent HPV vaccine was approved for both the routine and catch-up vaccination programs in Japan. In this study, we investigated the potential effects of the introduction of the 9-valent vaccine on the increased risk of cervical cancer in females born after fiscal year (FY) 2000. We estimated the lifetime relative risk of cervical cancer incidence and death using the improved routine and catch-up vaccination rates after the recent resumption of the governmental recommendation for women and girls to have the HPV vaccination. These relative risks were calculated using a lifetime risk of 1.000 for cervical cancer incidence and death for females born in FY 1993. We predicted that even if a 90% vaccination rate were to be achieved by FY 2024 with the 9-valent vaccine among women born between FY 2000 and FY 2005, the risk would remain higher than for the vaccination generation. Therefore, for women born between FY 2000 and FY 2005, it will be necessary to significantly improve the cervical cancer screening rate to compensate for this increased risk.

Intentions for catch-up HPV vaccination in Japan: an internet survey.

PURPOSE: In Japan, Japan's Ministry of Health, Labor, and Welfare decided to suspend govermental recommendation for HPV vaccination in FY 2013. The HPV vaccination rate for those born in FY 2000 or thereafter declined dramatically. In 2021, the "suspension of recommendation" ended. The catch-up vaccinations for the unvaccinated have been offered nationwide from FY 2022 to FY 2024. We aimed to quantify the vaccination intentions and characteristics of those young women now eligible for catch-up vaccination.  METHODS: In February of 2022, we conducted an internet survey targeted women who were born in 1997-2004 but who had not yet been HPV vaccinated. RESULTS: We received 1,648 valid responses. 41.6% of the respondents wanted to uptake the catch-up HPV vaccination, 29.7% were undecided, and 28.7% did not want to be vaccinated. The intention to uptake catch-up HPV vaccination was associated with a good history of gynecological visits, intention to receive cervical cancer screening, sexual activity, degree of anxiety about cervical cancer, familiarity with problems associated with cervical cancer, experience with vaccination recommendations, and knowledge about cervical cancer (p < 0.05, respectively). In the vaccinated generation, the proportion of the group that did not want to be vaccinated was significantly higher (p < 0.05). In the vaccine-suspended generation, the proportion of the group that wanted to be vaccinated was significantly higher (p < 0.05). CONCLUSION: Our survey revealed that catch-up vaccination intentions differed depending on the vaccination environment. It is necessary for all organizations involved with HPV vaccination, such as government, medical institutions, and educational institutions, to make recommendations based on an understanding of the characteristics of the "vaccinated generation" and the "vaccine-suspended generation".

A questionnaire survey on the prevention of HPV infection among females and males who came of age in Japan under various scenarios of HPV vaccine recommendation.

The Japanese Ministry of Health, Labor and Welfare (MHLW) temporarily suspended recommendation for HPV vaccinations for girls in June 2013. It resumed its recommendation in November 2021. To compensate for eight years of lost overage, a 'catch-up HPV vaccination' program began in April 2022. To determine intervention needs in regards to HPV vaccine hesitancy, from October 13 2021 to April 31 2022, we surveyed 12-28 year-old vaccine-eligible males and females (281 males, 583 females). We investigated the gender and 'vaccine generational' differences in attitudes, perceptions, and future intentions regarding HPV vaccination. Two generations were defined by the vaccine recommendation environment they grew up in. The 'vaccine generation' was born in FY 1994-1999; the 'vaccine-suspension generation' born in FY 2000-2009. Knowledge regarding the HPV vaccine correlated significantly with being female, of the vaccination generation, a medical student, and having received the COVID-19 vaccine. There was a significant 'generational' difference in terms of approval of the MHLW's recommendation resumption. The attitudes, perceptions, and future intentions of Japan's two generation groups are unique and should be dealt with accordingly. HPV vaccination promotion should consider the strong gender differences we identified. As an extension of the anti-cervical cancer program, HPV vaccinations for boys should begin immediately. Our study of their unique outlooks will contribute to the discussion surrounding that implementation.

Disparities among Japanese municipalities in recommendations for routine and catch-up HPV vaccinations.

In November 2021, the government of Japan announced a reversal of its decision in 2013 to suspend the previous proactive recommendation for HPV vaccination. However, the program for young girls to receive routine and catch-up vaccinations has not necessarily developed as expected. We conducted a nationwide questionnaire survey by mail in September 2022. The survey was mailed to 133 municipalities consisting of all cities/wards of the Tokyo and Osaka Prefectures and all other prefectural capital cities. Responses were received from 82 municipalities (62.7%). Notification of routine HPV vaccinations had already been sent to 76 (92.7%) of the municipalities; 70 (85.4%) had been encouraged to promote catch-up vaccinations. The questionnaire forms for registration and pre-vaccination screening for routine immunization had been sent to 74.1% (60/81) of the municipalities and 68.8% (55/80) for catch-up immunizations. For catch-up vaccination, only 54 municipalities (65.9%) had detailed vaccination records for those eligible. In total, 10 municipalities (12.2%) had virtually no vaccination records because these had already been discarded. In addition, 61 municipalities (74.4%) had notified only women and girls eligible for a catch-up vaccination based on their vaccination record, whereas 25.6% (21/82) of the municipalities reported that they had sent, or would send, the notification to all women and girls within the targeted grades, including those who had already been vaccinated with three injections. The survey revealed disparities among the municipalities in their HPV vaccine notification processes. Future research on monitoring HPV vaccination rates and incidence rates of cervical cancer and precancerous lesions in each municipality will be desirable.

The 'best friend effect': a promising tool to encourage HPV vaccination in Japan.

BACKGROUND: In Japan, HPV vaccination rates has dramaticaly declined since 2013. Since mothers are the ones making the decision to vaccinate their daughters against HPV, we probed the mothers' intention to receive vaccinations for themselves and to vaccinate their daughters against HPV, and their reasoning. METHODS: An internet survey was conducted in March of 2021. Through the screening, 1576 participants were extracted from a survey panel and divided into 3 groups based on their daughter's birth fiscal year (Group 1: 1994 to 1999, Group 2: 2000 to 2003, Group3: 2004 to 2008). The chi-square test and residual analysis were used for the statistical analysis of comparison among the groups. Logistic regression analysis was used to identify independent variables with mothers intention to get their daughters vaccinated under specific situations. RESULTS: The percentage of respondents without anxiety regarding their daughter's general vaccination was significantly higher in Group 1 (p < 0.05). In the mothers of daughters born in or after 2000 when vaccination rates declined (Groups 2 and 3), a situation in which 'The daughter's best friends were vaccinated before her' made the mothers think positively about HPV vaccination, and to the same degree as a situation in which 'You received a notice from your local government recommending vaccination' (Group 2: 41.6% (214/514) and 40.5% (208/514), Group 3: 48.5% (257/530) and 47.0% (249/530)). CONCLUSION: If mothers who have had their daughters vaccinated were to recommend HPV vaccination to their close friends, 'the best friend effect' should promote others to be vaccinated.

Can Catch-Up Vaccinations Fill the Void Left by Suspension of the Governmental Recommendation of HPV Vaccine in Japan?

In 2013, the Ministry of Health, Labor, and Welfare (MHLW) in Japan announced a suspension of the governmental recommendation for routine HPV vaccinations. In 2020, MHLW started individual notifications of HPV vaccine to the targeted girls. In April 2022, the governmental recommendation was restarted, and catch-up vaccinations started. We evaluated the benefits and limitations of the MHLW's new vaccination strategies by estimating the lifetime risk for cervical cancer for each birth FY under different scenarios to suggest a measure for the vaccine suspension generation. It was revealed that catch-up immunization coverage among the unvaccinated must reach as high as 90% in FY2022, when the program begins, in order to reduce the risk of the females already over the targeted ages to the same level or lower than that of women born in FY1994-1999 who had high HPV vaccination rates. For women whose vaccination coverage waned because of their birth FYs, strong recommendations for cervical cancer screening should be implemented.

Change of HPV vaccination rates in Japan: the effect of individual notifications implemented by local governments.

BACKGROUND: In Japan, in June 2013, The Ministry of Health, Labor and Welfare (MHLW) decided to temporarily suspend its official recommendation for the participation of girls in the national immunization program. The HPV vaccination rate in Japan soon declined to below 1%. In October 2020, the MHLW notified that the municipalities could and should begin to individually notify girls and their parents targeted for routine vaccination. We have examined how that type of individual notification has affected the number of vaccinations. METHODS: From 12 municipalities (with a combined total population of approximately 4.06 million), we collected vaccination data for all girls who attended grades 6 through 10 from April 2019 to March 2021. We analyzed the number of initial-round vaccinations that occurred by month and the timing and the subjects of the individual notifications. RESULTS: The annual vaccination rate for tenth-grade students in 2020 in the six municipalities that had implemented individual notification was 9.46% (342/3618), which was significantly higher than the rate of 3.22% (54/1676) in the three municipalities that had not implemented individual notification (p < 0.001). On the other hand, the annual vaccination rate for the sixth to ninth-grade students in 2020 in the six municipalities that had implemented individual notification was not significantly (p = 0.56) higher than the rate in the three municipalities that did not: 1.43% (197/13,785) versus 1.33% (83/6260), respectively. CONCLUSION: This study clearly demonstrates the importance of providing information for routine vaccination directly to the targets and their parents.

Effectiveness of human papillomavirus 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.

Attitudes and behaviors of obstetricians and gynecologists toward HPV vaccination: a 7-year follow-up survey in Japan.

BACKGROUND: In Japan, the government suspended HPV vaccine recommendation in 2013, resulting in dropping vaccination uptake to almost zero. We conducted four serial surveys on our colleague' attitude to HPV vaccination between 2014 and 2021. Here, we evaluate the result of the survey in 2021 and compare it to previous surveys. METHODS: The subjects were 567 obstetricians and gynecologists who had been trained in our university hospital or our affiliated hospitals. We used a questionnaire similar in format to those used in 2014, 2017, and 2019. RESULTS: A total of 340 doctors (60.0%) completed the survey. Among them, 93.2% (317/340) of respondents thought that the government should restart HPV vaccination recommendation, and that 63.2% (215/340) think male teenagers should also vaccinate against HPV. The percentage of teenaged daughters inoculated with HPV vaccination after Japanese government had suspended its recommendation was 43.5% (20/46), an increasing trend from the previous surveys. 39 out of the 46 daughters (84.8%) would be expected to receive full HPV vaccination after they take junior high school entrance examination or after 9-valent HPV vaccination is designated as a national routine-immunization. CONCLUSION: This study revealed increasing number of our colleagues think HPV vaccination is necessary for prevention of cervical cancer. The Japanese government's decision to resume its recommendation of the HPV vaccine in November 2021 will lead to a change in the public's thinking and behavior toward the HPV vaccine.

Impact of the Threat of COVID-19 Infections on the Perceived Risk to HPV Vaccination.

Vaccination rates for human papillomavirus (HPV) in Japan are significantly lower than other countries, and Japanese people are reluctant to be vaccinated. Repeated daily reports of COVID-19 infections and restrictions have made people more health conscious and aware of the danger of infectious diseases. In this study, we used the health belief model (HBM) to examine perceived threats of cancer and infectious diseases and to ascertain whether the new COVID-19 vaccination in addition to these perceived threats would increase vaccination intention against cervical cancer. We conducted a cluster analysis to classify the segmentation regarding the perceived threat, and a logistic regression analysis to predict factors influencing people accepting vaccination. We received 1257 completed surveys during our research. We classified the participants into six clusters, and the logistic regression analysis indicated eight factors significantly associated with the willingness to get the HPV vaccine: reliable information sources such as doctors and social networking sites (SNS), the recognition of COVID-19 symptoms, the awareness of COVID-19 vaccination, the importance of HPV prevention through vaccination, one's own intention of COVID-19 vaccination, their intention of COVID-19 vaccination toward children, and benefits of HPV vaccination. Further research on HPV and COVID-19 vaccination is encouraged.

Development of information dissemination methods that contribute to improving maternal and child healthcare using social networking sites: a community-based cross-sectional study in Japan.

BACKGROUND: In recent years, feelings of isolation among mothers caring for small children has become a significant social issue in Japan. The purpose of this study is to develop a message to alleviate their loneliness, to evaluate the impact of social networking sites (SNS) for delivering such messages, and to propose means of more effective information transmission to promote health for mothers raising small children. METHODS: Our study was conducted in two stages, first an interview and then a cross-sectional study of the mothers involving a questionnaire survey. The interview was targeted two public-health nurses caring for mothers. Based on these interviews, we developed six messages intended to alleviate the mothers' sense of loneliness, which were vetted by seven mothers. The second stage was to conduct a questionnaire survey of mothers both before and after our selected message as advertisement on Instagram and analyzed the effect. The surveys were collected during routine child health check-ups in the City of Takatsuki, Japan. RESULTS: From the six draft messages created based on interviews with public health nurses, we selected the message that most relieves the feeling of loneliness of the mothers who are raising small children. The survey questionnaire was taken by 494 mothers prior to our posting of Instagram advertisements (ads), and afterwards by 419 mothers. The percentage of mothers feeling loneliness tended to decrease after reading the messages (before ads.:8.1%, after ads.:5.8%). 8.6% of the mothers (36/419) remembered seeing the Instagram ads. Mothers with financial anxiety were significantly more likely to have remembered seeing the Instagram ads (p < 0.01). CONCLUSIONS: Our results indicate that usefulness of SNS messaging for mothers raising small children may reduce their feeling of loneliness. Among the SNS, disseminating child-rearing information on Instagram may be more effective for people with financial instability.

Challenge to improve Japan's deplorable HPV vaccination rate by local government actions.

AIM: In Japan, in 2013, following reports of several alleged adverse reactions in young girls following vaccination, the previously successful national human papillomavirus infection (HPV) vaccination program collapsed rapidly. In the 8 years since vaccination rates have hovered near zero. In October of 2020, in an attempt to mitigate this lingering disaster, the Japanese Ministry of Health, Labor, and Welfare (MHLW) agency finally revised its HPV vaccination informational leaflet that was designed to be distributed by local governments nationwide. Prior to this revision, Toyonaka City, in Japan's Osaka province, had already begun sending out their own unique leaflet to girls in the targeted 6th-10th grades. As a preview of how MHLW's revised leaflet might eventually succeed, we have studied the HPV vaccination results from Toyonaka City's experiment. METHOD: This study was a population-based analysis that compared the monthly rates of new vaccinations in girls of a targeted grade school age group. We looked at rates before and after the leaflets were sent by Toyonaka City's Division of Health Promotion and Senior Services. RESULTS: The vaccination rates between April 2020 and March 2021 were improved across all grades; 1.2% in 6th grade (p = 0.000185), 2.5% in 7th grade (p < 0.0001), 3.5% in 8th grade (p < 0.0001), 6.8% in 9th grade (p < 0.0001), and a remarkable 16.5% in 10th grade (p < 0.0001). CONCLUSION: When a local government sends an HPV informational leaflet targeted at young girls, it can significantly improve their HPV vaccination rates.

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.

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

In Japan, public funding for HPV vaccination began in 2010 for girls aged 13-16 years (birth cohort years 1994-1997) and women born in 1994 who turned 25 in 2019. We aimed to verify the long-term effectiveness of the bivalent HPV vaccine in women aged 25 years. Subjects were women aged 25-26 years who underwent cervical cancer screening and HPV testing in Niigata from 2019 to 2020 (birth cohort years 1993-1994). Information on vaccination status and sexual behavior was obtained from a questionnaire and municipal records. We compared the HPV infection rates of the vaccinated and unvaccinated groups. Of the 429 registrants, 150 (35.0%) and 279 (65.0%) were vaccinated and unvaccinated, respectively. The average period from HPV vaccination to HPV testing was 102.7 months (8.6 years), with a median of 103 months (range 92-109 months). The HPV high-risk infection rate was 21.3% (32/150) in the vaccinated group and 23.7% (66/279) in the unvaccinated group (P = 0.63). The HPV16/18 infection rate was 0% (0/150) in the vaccinated group and 5.4% (15/279) in the unvaccinated group, showing a significant difference (P = 0.0018), and the vaccine effectiveness was 100%. The cross-protective type HPV31/45/52 infection rate in the vaccinated group was significantly lower than that in the unvaccinated group (3.3% vs. 10.0%, P = 0.013). There was no significant difference in the mean age at sexual debut and the number of previous sexual partners between the two groups. We have demonstrated the long-term 9-year effectiveness of the bivalent vaccine against HPV infection for the first time in Japan.