Background: Japan lacks comprehensive reports on the nationwide voluntary vaccine coverage. The effectiveness of public subsidies in promoting vaccination has not been fully investigated. Therefore, we aimed to estimate the nationwide coverage of voluntary vaccines, compare it with that of national immunization program (NIP)-included vaccines, and investigate the effectiveness of public subsidies.

Methods: We obtained nationwide monthly vaccine market data for rotavirus, Haemophilus influenzae type b (Hib), diphtheria, tetanus toxoid, acellular pertussis, inactivated poliovirus (DTaP-IPV), and mumps vaccines; estimated recipient numbers; and calculated coverage as the proportion of children from October 2011 to March 2022. Regarding the NIP-included vaccine, we compared vaccine coverage calculated from nationwide annual market data with that estimated by World Health Organization (WHO)/United Nations Children’s Fund (UNICEF), using Bland-Altman analysis.

Results: The estimates of Hib and DTaP-IPV vaccine coverage derived from market data were slightly higher than the WHO/UNICEF estimates, with mean differences of 0.05 (95% CI: 0.02–0.07) for Hib and 0.03 (95% CI: 0.01–0.05) for DTaP-IPV. The coverage of the rotavirus vaccine gradually increased long before the implementation of national subsidies, reaching 0.9 in 2020. Hib vaccine coverage had already achieved 1.0 by January 2012. The coverage of the DTaP-IPV vaccine was approximately 0.6–0.8 in 2013, reaching 1.0 in 2014. The coverage of mumps vaccine increased gradually from 2011 to 2021.

Conclusions: Despite the possibility of overestimation, our estimates may serve as a valuable surrogate for actual vaccine coverage in Japan. An increasing trend in rotavirus and mumps vaccine coverage was observed when these vaccines were categorized as voluntary. Although vaccination policies differ from country to country, it would be beneficial to share findings on the impact of subsidies in Japan with other countries.

Background: Children’s respiratory health demonstrates particular sensitivity to air pollution. Existing evidence investigating the association between short-term ozone (O₃) exposure and childhood pneumonia remains insufficient and inconsistent, especially in low- and middle-income countries (LMICs).

Method: To provide more reliable and persuasive evidence, we implemented a multi-city, time-stratified case-crossover design with a large sample size, using data from seven representative children’s hospitals across major geographical regions in China. To avoid the impact of the COVID-19 pandemic, individual-level medical records of inpatient children under 6 years of age diagnosed with pneumonia during 2016–2019 were collected. Conditional logistic regression models were fitted for each city, and city-specific estimates were pooled through a meta-analysis using a random-effects model.

Results: In total, the study included 137,470 pediatric pneumonia hospital admissions. The highest pooled estimate for O₃ occurred at lag0–1, with a 10 µg/m³ increase in O₃ associated with a 1.57% (95% CI: 0.67%–2.48%) higher risk of pediatric pneumonia hospital admissions. Stratified analyses indicated that the effects of O₃ were robust across different sexes, age groups, and admission seasons. We also observed a statistically significant increase in risk associated with O₃ concentrations exceeding the World Health Organization Air Quality Guidelines (WHO-AQGs).

Conclusions: This study revealed a significant positive association between O₃ and pediatric pneumonia hospital admissions. Our findings substantially strengthen the evidence base for the adverse health impacts of O₃, underscoring the importance of O₃ pollution control and management in reducing the public health burden of pediatric pneumonia.

Background: Supporting the mental health of researchers is essential to maintaining human resources and advancing science. This study investigated the association between Japanese medical researchers’ perceptions of research evaluation processes and their psychological well-being.

Methods: We performed a web-based self-administered questionnaire survey. The questionnaires were distributed to each academic society through the Japanese Association of Medical Sciences from December 2022 to January 2023. These questionnaires targeted medical researchers. Exposure was the medical researchers’ perceptions of quantitative indicators for evaluating medical research and researchers. The outcome was psychological well-being, measured using the Japanese version of the World Health Organization-Five Well-Being Index (WHO-5). Multivariable-adjusted logistic regressions were conducted to investigate the association between individual attitudes toward research evaluation and psychological well-being. Stratified analyses by research fields, i.e., clinical, basic, and social medicine, were also performed.

Results: A total of 3,139 valid responses were collected. After excluding 176 responses from research fields of other than clinical, basic, or social medicine, 2,963 researchers (2,185 male, 737 female, and 41 other) were analyzed. Prevalence of poor well-being (WHO-5 score <13) was 28.3% in the researchers. The highest number of medical researchers was in clinical medicine (n = 500) followed by basic medicine (n = 217) and social medicine (n = 121). Medical researchers who considered research funding slightly important/not important for researcher evaluation had poorer psychological well-being than those who considered it especially important (slightly important: adjusted odds ratio (aOR) 1.33, 95% confidence interval (CI) 1.03–1.71; not important: aOR 1.53, 95%CI 1.10–2.12). This tendency was stronger among basic medical researchers than clinical or social medical researchers. The research field significantly modified the relationship between research funding received and interaction with poor psychological well-being both additively (P = 0.030) and multiplicatively (P = 0.024).

Conclusions: The discrepancy between medical researchers’ attitudes toward research evaluation and the current state of research evaluation in their research community may worsen their psychological well-being. The influence of this discrepancy differs among clinical, basic, and social medicine. Appropriate evaluation of medical research and researchers in each field can facilitate improving their psychological well-being via the resolution of this discrepancy.

Per- and polyfluoroalkyl substances (PFAS) have recently been shown to affect human health at low levels in the blood, according to epidemiological evidence. Consequently, human exposure to these chemicals should be strictly controlled to prevent health risks. This review reports on the potential sources of PFAS using Japan as an example. Tap water has attracted attention as a source of exposure to PFAS. PFAS have also been detected in the air, in household dust, and in consumer products. Furthermore, in the general population, diet is the most common source of exposure, and there is particular concern about human exposure to PFAS accumulated in seafood. Continuous monitoring is important for appropriate management of exposure for both humans and the environment.

Background: Previous studies have shown that old age and cold temperatures are risk factors for bathing-related accidents (BRAs) in Japan. The differences between outdoor and indoor temperatures are believed to depend on the housing type (detached houses or apartment buildings). This study aimed to investigate the associations between age, temperature, and BRAs according to housing type in Japan.

Methods: We included cases in which patients were transported by ambulance from domestic bathrooms between April 2016 and March 2022 in Nagoya city. Age-specific BRA incidence rates measured by 5-year age groups, temperature-specific age-adjusted standardized incidence rates (SIRs) for BRA calculated by temperature quintile groups, and the BRA risk regarding temperature based on a time-stratified case-crossover (CCO) design were compared between detached houses and apartment buildings.

Results: We observed 4,848 ambulance dispatches owing to BRAs (3,083 in detached houses and 1,765 in apartment buildings; SIR for detached houses compared to apartment buildings: 1.37; 95% confidence interval [CI]: 1.33–1.43). The ratio of detached houses to apartment buildings in the age-specific BRA incidence was almost the same in middle-aged people, but it significantly increased from the age of 70 years onward (incidence rate ratio for the 70–74-years age group: 1.74; 95% CI: 1.43–2.11). Temperature-specific SIR for detached houses compared to apartment buildings was not significantly different in the hottest temperature quintile but increased significantly in the other colder temperature quintiles (SIR in coldest quintile: 1.56; 95% CI: 1.47–1.66). BRA risk based on CCO design increased significantly with a decrease in temperature in detached houses (risk ratio [RR] for 3 °C: 1.25; 95% CI: 1.05–1.47), but not in apartment buildings (RR for 3 °C: 1.07; 95% CI: 0.86–1.34).

Conclusions: Detached houses had higher BRA incidence rates than apartments. Older age and lower temperatures, which are risk factors for BRAs, were more prevalent in detached houses than in apartment buildings. Thus, public health measures that focus on detached houses are necessary for preventing BRAs in Japan.