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Introduction: Post-COVID-19 conditions have emerged as a global health challenge. This study examined the long-term effects of COVID-19 vaccination on the incidence and risk of post-COVID-19 conditions in Japan., Methods: This retrospective cohort study was conducted using a database comprising medical claims, COVID-19 case information, and vaccination records of persons residing in four Japanese municipalities. The cohort included COVID-19 cases diagnosed between August 2020 and December 2022. Participants were classified according to the duration between their most recent COVID-19 vaccination and COVID-19 occurrence (≥365 days, 150-364 days, and 14-149 days). The incidences of 36 post-COVID-19 conditions were monitored for 3, 5, and 8 months after infection. Cox proportional hazards models were used to calculate the risk of developing each post-COVID-19 condition within 8 months after infection according to vaccination status., Results: From among 84,464 participants, 9642 (11.4 %) developed post-COVID-19 conditions over 8 months. The 8-month risks of developing 28 (including various respiratory conditions, cardiovascular conditions, inflammatory and immune diseases, physical conditions, psychiatric conditions, and endocrine disorders) of the 36 target conditions were significantly lower when individuals had been recently vaccinated (14-149 days) before infection., Conclusions: COVID-19 vaccination can reduce the incidence and risk of post-COVID-19 conditions if administered within 5 months before infection. Despite having the highest mean age and prevalence of comorbidities, individuals who were most recently vaccinated had a lower risk of developing post-COVID-19 conditions. These results provide important evidence for future COVID-19 vaccination strategies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Objectives: Although COVID-19 no longer constitutes a Public Health Emergency of International Concern, vaccination remains an important tool for reducing disease burden and mitigating future outbreaks. However, little is known about the impact of vaccination on medical expenditures and hospitalization duration after breakthrough infection. This study aimed to examine this impact during the Delta wave in Japan., Methods: This retrospective study was conducted using medical care claims data, vaccination records, and COVID-19-related information. COVID-19 cases in three municipalities were categorized into two age groups: 20-64 years and ≥65 years. For each group, we constructed linear regression models with a generalized estimating equation. We calculated the risk ratios (RRs) and 95% confidence intervals (CIs) of COVID-19 vaccination for total medical expenditures and hospitalization duration after adjusting for sex, comorbidities, and municipality., Results: We analyzed 618 cases aged 20-64 years (mean age: 38.4 years, women: 45.1%) and 208 cases aged ≥65 years (76.4 years, 53.8%). The RRs (95% CIs) of vaccination for total medical expenditures were 0.53 (0.44-0.64) in the 20-64 years age group and 0.51 (0.39-0.66) in the ≥65 years age group. Next, the RRs (95% CIs) of vaccination for hospitalization duration were 0.59 (0.42-0.83) in the 20-64 years age group and 0.69 (0.49-0.98) in the ≥65 years age group., Conclusions: COVID-19 vaccination was associated with lower total medical expenditures and hospitalization duration after breakthrough infection, with a more pronounced effect in older persons., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: Little is known about the impact of physical activity (PA) and PPSV23 vaccination on pneumonia-related hospitalizations. This study examined the association between regular PA and pneumonia-related hospitalization according to PPSV23 vaccination status in older adults., Methods: This retrospective cohort study was conducted using health checkup data, medical care claims data, and vaccination records from two Japanese municipalities. Residents aged ≥65 years who had undergone a health checkup between April 2016 and March 2021 were categorized into a PPSV23 vaccinated or unvaccinated cohort. Each cohort was further divided into a PA group and no PA group. The hazard ratio (HR) of PA for pneumonia-related hospitalization was calculated for each cohort while adjusting for sex, age, comorbidities, and metabolic syndrome., Results: The vaccinated cohort comprised 16,295 participants (no PA: 5,139, PA: 11,156), and the unvaccinated cohort comprised 7,998 participants (no PA: 2,671, PA: 5,327). In the vaccinated cohort, the PA group had a significantly lower hazard for pneumonia-related hospitalization than the no PA group (adjusted HR: 0.58, P = 0.004). However, PA was not associated with pneumonia-related hospitalization in the unvaccinated cohort (adjusted HR: 0.70, P = 0.270)., Conclusions: PA can reduce the risk of pneumonia-related hospitalization in vaccinated persons. Interventions that increase both vaccination rates and PA habits may help to reduce these hospitalizations in older adults., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Purpose: To investigate individual and environmental vaccination-related factors among the older adults in Japan, using administrative data., Methods: We conducted a cohort study and included people who reached the relevant age (≥65 years) for routine pneumococcal vaccination of older adults between April 2015 and March 2020. Monthly data of residents in the two municipalities from April 2014 to March 2020 and vaccination records from April 2015 to March 2020 were used. We defined five cohorts according to the year in which routine vaccinations were available. Each cohort was followed for a total of two years, with the first year being the "baseline period" and second year being the "vaccine follow-up period." Pneumococcal vaccination data was extracted from vaccination records at "first dose." Age, sex, socioeconomic status, comorbidities, hospital visit history, hospitalization history, Specific Health Check-ups participation, and information on contracted hospitals for pneumococcal vaccination were used as covariates. A multivariate logistic regression model was used to investigate the relationship between pneumococcal vaccination and vaccination-related factors. Odds ratios (OR) and 95 % confidence intervals (95 % CI) were calculated., Results: Analysis included 17,991 patients. Vaccination coverage was 33.6 % for all subjects. Multivariate analysis found the following as significant vaccination-related factors: female (OR: 1.18, 95 % CI: 1.11-1.26), not low income (1.76, 1.17-2.76), hospital visits: ≥once/month (1.27, 1.19-1.35), and Specific Health Check-ups participation (2.10, 1.95-2.27). No significant results were found for hospitals that contracted pneumococcal vaccination., Conclusions: Individual factors, such as sex and Specific Health Check-ups participation, were found to be important factors affecting pneumococcal vaccination among older adults in Japan. Environmental factors, such as the characteristics of residential areas, should be evaluated in further investigations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: To address the lack of an active vaccine safety surveillance system in Japan, the Vaccine Effectiveness, Networking, and Universal Safety (VENUS) study was initiated in 2021 as a pilot system using existing health insurance claims data and vaccination records., Methods: This study evaluated the value of the VENUS study by assessing the incidence of immune thrombocytopenic purpura (ITP) and Guillain-Barré syndrome (GBS) following vaccination with the 23-valent pneumococcal polysaccharide vaccine (PPSV23) using a self-controlled case series (SCCS) design., Results: Incidence rate ratios for ITP during 28-day and 42-day risk periods were 0.89 (95% confidence interval [CI], 0.12-6.4), and 0.58 (95% CI, 0.081-4.2), respectively. Neither was statistically significant. Incidence rate ratios could not be estimated for GBS due to the limited sample size., Conclusion: The VENUS study can provide valuable insights to facilitate the establishment of an advanced vaccine monitoring system in Japan., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Background: Although the effectiveness of coronavirus disease 2019 (COVID-19) vaccines is a crucial public health concern, evidence from Western Pacific countries is limited, including Japan. This study aimed to estimate the COVID-19 vaccines effectiveness (VE) against infection during the Delta variant predominance (July-September 2021) in Japan., Methods: We performed a test-negative study using COVID-19 test data of ≥20-year-old residents in four municipalities who were tested in medical institutions between July 1 and September 30, 2021. We extracted COVID-19 test data from healthcare claims data, and the vaccination status at the testing date was ascertained using the Vaccination Record System data. Confirmed positive cases were identified using data from the national system for COVID-19, Health Center Real-time Information-sharing System on COVID-19. Logistic regression analyses were conducted to estimate the odds of testing positive according to vaccination status. VE was calculated as (1 - odds ratio) × 100%., Results: This study included 530 positive and 15,650 negative results. Adjusted manufacturer-unspecified VE was 4.1% (95% confidence interval [CI], -36.5-32.6) at 0-13 days after the first dose, 45.2% (95% CI, 13.4-65.3) at ≥14 days after the first dose, 85.2% (95% CI, 69.9-92.7) at 0-13 days after the second dose, and 79.6% (95% CI, 72.6-84.8) at ≥14 days after the second dose. In addition, the VE after the second dose was highest at 14-34 days after the dose (VE, 89.1%; 95% CI, 80.5-93.9)., Conclusions: High real-world effectiveness of COVID-19 vaccines, especially two doses, against infection during the Delta variant predominance in Japan was confirmed., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Background: There are currently no COVID-19 vaccine assessment systems in Japan that allow for the active surveillance of both vaccinated and unvaccinated persons. Herein, we describe the development of Japan's first COVID-19 vaccine effectiveness and safety assessment system with active surveillance capabilities., Methods: The Vaccine Effectiveness, Networking, and Universal Safety (VENUS) Study was developed as a multi-source database that links four data types at the individual resident level: Basic Resident Register (base population information), Vaccination Record System (vaccination-related information), Health Center Real-time Information-sharing System on COVID-19 (HER-SYS; information on COVID-19 occurrence), and health care claims data (information on diagnoses, hospitalizations, diagnostic tests, and treatments). These data were obtained from four municipalities. Individual residents were linked across the data types using five matching algorithms based on names, birth dates, and sex; the data were anonymized after linkage. To ascertain the viability of the VENUS Study's database for COVID-19 vaccine assessments, we examined the trends in COVID-19 vaccinations, COVID-19 cases, and polymerase chain reaction (PCR) test numbers. We also evaluated the linkage rates across the data types., Results: Our multi-source database was able to monitor COVID-19 vaccinations, COVID-19 cases, and PCR test numbers throughout the pandemic. Using the five algorithms, the data linkage rates between the COVID-19 occurrence information in the HER-SYS and the Basic Resident Register ranged from 85·4% to 91·7%., Conclusion: If used judiciously with an understanding of each data source's characteristics, the VENUS Study can provide a viable data platform that facilitates active surveillance and comparative analyses for population-based research on COVID-19 vaccine effectiveness and safety in Japan., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The protective effect of the 23-valent pneumococcal polysaccharide vaccine (PPSV23) against cardiovascular disease has been investigated in the United States and Europe; however, its effect has not been fully established. This study aimed to investigate the protective effect of PPSV23 on cardiovascular events in adults aged ≥ 65 years. This population-based nested case-control study was conducted using the claims data and vaccine records between April 2015 and March 2020 from the Vaccine Effectiveness, Networking, and Universal Safety (VENUS) Study. PPSV23 vaccination was identified using vaccination records in each municipality. The primary outcome was acute myocardial infarction (AMI) or stroke. The adjusted odds ratios (aORs) with 95% confidence intervals (CIs) for PPSV23 vaccination were calculated using conditional logistic regression. Among 383,781 individuals aged ≥ 65 years, 5,356 and 25,730 individuals with AMI or stroke were matched with 26,753 and 128,397 event-free controls, respectively. Individuals who were PPSV23 vaccinated, compared with the unvaccinated individuals, had significantly lower odds of AMI or stroke events (aOR, 0.70 [95% CI, 0.62-0.80] and aOR, 0.81 [95% CI, 0.77-0.86], respectively). More recent PPSV23 vaccination was associated with lower odds ratios (AMI, aOR 0.55 [95% CI, 0.42-0.72] for 1-180 days and aOR 1.11 [95% CI, 0.84-1.47] for 720 days or longer; stroke, aOR 0.83 [95% CI, 0.74-0.93] for 1-180 days and aOR 0.90 [95% CI, 0.78-1.03] for 720 days or longer). Among Japanese older adults, individuals who were PPSV23 vaccinated, compared with unvaccinated individuals, had significantly lower odds of AMI or stroke events., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: [Haruhisa Fukuda reports financial support was provided by Japan Agency for Medical Research and Development. Haruhisa Fukuda reports financial support was provided by Japan Society for the Promotion of Science. Haruhisa Fukuda reports financial support was provided by Japan Science and Technology Agency]., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Background: Japan currently lacks a data platform that can support quantitative assessments of the causal relationships between vaccines and adverse events. This study describes the development and application of the Vaccine Effectiveness, Networking, and Universal Safety (VENUS) Study to facilitate such assessments., Methods: A database was created by linking public insurance enrollees' claims data with vaccination records acquired from participating municipalities. To provide an overview of the study data, we produced descriptive statistics of sex, age, and vaccinations. We also conducted a pilot study using the database to assess influenza vaccine safety during the 2018/2019 season among older persons (≥65 years) residing in a single municipality., Results: Our database was created using data from approximately 1.12 million individuals in 7 municipalities between 2013 and 2020. The data during fiscal year 2018 included 853,016 individuals (male: 363,079, female: 489,937) with a median age of 70 years (interquartile range: 52-79). We obtained information on 17 vaccine types, including the pneumococcal vaccine and influenza vaccine. In the pilot study, we analyzed 48,723 vaccinated persons matched with 48,723 unvaccinated persons. The only adverse event that occurred in both groups was Bell's palsy, which had an adjusted incidence rate ratio of 1.21 (95 % confidence interval: 0.48-3.07)., Conclusions: The VENUS Study is Japan's first healthcare data platform that enables comparative assessments of vaccinated and unvaccinated persons in large samples covering all age groups. Efforts are underway to increase the number of participating municipalities and to generate evidence on vaccine effectiveness and safety., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. The funders did not have any role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript., (Copyright © 2022 The Author(s). Published by Elsevier Ltd.. All rights reserved.)