Background: Although the effectiveness of BNT162b2 messenger RNA vaccines against the Omicron variant has been reported in several countries, data are limited in children living in Asian countries. Therefore, this study aimed to estimate the effectiveness of the pediatric primary two-dose monovalent mRNA vaccine series in preventing symptomatic novel coronavirus disease 2019 (COVID-19) in Japan.

Methods: We conducted a test-negative case-control study (262 test-positive cases and 259 test-negative controls) in patients aged 5–11 years who presented with COVID-19-like symptoms during the Omicron BA.2- and BA.5-predominant periods. Vaccination status, demographic data, underlying medical conditions, lifestyle, personal protective health behaviors, living environment, and PCR test results were obtained using parent-administered questionnaires and clinical records. Vaccine effectiveness (VE) against symptomatic COVID-19 was calculated using a multivariate logistic regression analysis.

Results: Of the test-positive cases and test-negative controls, 9.2% (n = 24) and 12.7% (n = 33) received two vaccine doses, respectively. Having siblings and a BA.5-dominant period were significantly associated with symptomatic COVID-19. After adjusting for age, siblings, study period, and duration after the last vaccination, the overall VE of two-dose vaccination was 50.0% (95% confidence interval [CI], 5–74%). VE was 72% (95% CI, 24–89%) within 3 months after the two-dose vaccination, while it decreased to 24% (95% CI, −80% to 68%) after 3 months.

Conclusion: Two BNT162b messenger RNA vaccine doses provided moderate protection against symptomatic COVID-19 during the Omicron variant period. A time-dependent decrease in VE was noted after the second dose; thus, a booster dose 3 months after the second dose is warranted.

Background: Associations of major risk factors for stroke with total and each type of stroke, as well as subtypes of ischemic stroke, and their population attributable fractions had not been examined comprehensively.

Methods: Participants of the Japan Public Health Center-based prospective (JPHC) Study Cohort II without histories of cardiovascular disease and cancer (n = 14,797) were followed from 1993 through 2012. Associations of current smoking, hypertension, diabetes, overweight (body mass index ≥25 kg/m²), non-high-density lipoprotein cholesterol (non-HDLC) categories, low HDLC (<40 mg/dL), urine protein, and history of arrhythmia were examined in a mutually-adjusted Cox regression model that included age and sex. Population attributable fractions (PAFs) were estimated using the hazard ratios and the prevalence of risk factors among cases.

Results: Subjects with hypertension were 1.63 to 1.84 times more likely to develop any type of stroke. Diabetes, low HDLC, current smoking, overweight, urine protein, and arrhythmia were associated with risk of overall and ischemic stroke. Hypertension and urine protein were associated with risk of intracerebral hemorrhage, while current smoking, hypertension, and low non-HDLC were associated with subarachnoid hemorrhage. Hypertension alone accounted for more than a quarter of stroke incidence, followed by current smoking and diabetes. High non-HDLC, current smoking, low HDLC, and overweight contributed mostly to large-artery occlusive stroke. Arrhythmia explained 13.2% of embolic stroke. Combined PAFs of all the modifiable risk factors for total, ischemic, and large-artery occlusive strokes were 36.7%, 44.5%, and 61.5%, respectively.

Conclusion: Although there are differences according to subtypes, hypertension could be regarded as the most crucial target for preventing strokes in Japan.

Background: Administering premixed drugs in commodity packets was first reported in Asia in 2015, but there continues to be a dearth of related population-based data. This study aimed at examining (1) the prevalence of drug-packet use in the population and (2) the sociodemographic profiles, particularly gender distribution, of drug-packet users.

Methods: Data were derived from a survey of 18,626 Taiwanese civilians, aged 12–64 years, using stratified, multi-stage, random sampling in 2018. Participants anonymously completed a computer-assisted self-interview on tablet computers which covered the use and problematic use of illicit drugs/inhalants, prescription drugs, and other psychoactive substances.

Results: Approximately 1.46% of respondents had a lifetime use of illicit drugs, with drugs in commodity packets (0.18%) being ranked the fifth-most commonly used illicit drugs, higher than nitrous oxide (0.14%) and heroin (0.09%). Ten formats of drug packets were endorsed by users. Approximately 81.6% of persons with drug packet use had lifetime use of other illicit drugs. The correlates of the use of drugs in commodity packets were different from those of the exclusive use of other drugs, particularly concerning the lack of gender differences in the former category in the whole sample and the subgroups of various sociodemographic characteristics and other substance use.

Conclusion: Drugs in commodity packets have become a common way of administering illicit drugs in the population in Taiwan, and there were no gender differences among users. Our findings have implications for more efficient drug testing and culturally appropriate intervention for drug-packet use.

Background: The present genome-wide association study (GWAS) aimed to reveal the genetic loci associated with folate metabolites, as well as to detect related gene–environment interactions in Japanese.

Methods: We conducted the GWAS of plasma homocysteine (Hcy), folic acid (FA), and vitamin B₁₂ (VB₁₂) levels in the Japan Multi-Institutional Collaborative Cohort (J-MICC) Study participants who joined from 2005 to 2012, and also estimated gene–environment interactions. In the replication phase, we used data from the Yakumo Study conducted in 2009. In the discovery phase, data of 2,263 participants from four independent study sites of the J-MICC Study were analyzed. In the replication phase, data of 573 participants from the Yakumo Study were analyzed.

Results: For Hcy, MTHFR locus on chr 1, NOX4 on chr 11, CHMP1A on chr 16, and DPEP1 on chr 16 reached genome-wide significance (P < 5 × 10⁻⁸). MTHFR also associated with FA, and FUT2 on chr 19 associated with VB₁₂. We investigated gene-environment interactions in both studies and found significant interactions between MTHFR C677T and ever drinking, current drinking, and physical activity >33% on Hcy (β = 0.039, 0.038 and −0.054, P = 0.018, 0.021 and <0.001, respectively) and the interaction of MTHFR C677T with ever drinking on FA (β = 0.033, P = 0.048).

Conclusion: The present GWAS revealed the folate metabolism-associated genetic loci and gene–environment interactions with drinking and physical activity in Japanese, suggesting the possibility of future personalized cardiovascular disease prevention.

Background: Symptoms after novel coronavirus disease 2019 (COVID-19) recovery by severe acute respiratory syndrome coronavirus 2 strains are unspecified.

Methods: This self-administered questionnaire-based study was conducted to investigate symptoms after COVID-19 recovery at one of the main hospitals for COVID-19 treatment in Hiroshima, Japan, from September 2020 to March 2022 for patients who visited follow-up consultations after COVID-19. Study subjects were divided into four groups (Wild-type, Alpha, Delta, and Omicron periods) according to COVID-19 onset date. Hierarchical cluster analysis was performed to determine symptom clusters and investigate risk factors for each symptom cluster using multivariate analysis.

Results: Among 385 patients who enrolled in this study, 249 patients had any persistent symptoms at a median of 23.5 (interquartile range, 20–31) days after COVID-19 onset. Among patients with any persistent symptoms, symptom clusters including olfactory or taste disorders, respiratory symptoms, and cardiac symptoms were found. Respiratory symptoms were more frequent among patients infected in the Omicron period compared to the Wild-type period (adjusted odds ratio [AOR] 3.13; 95% confidence interval [CI], 1.31–7.48). Compared to patients who recovered from mild COVID-19, patients who needed oxygen or ventilation support suffered fewer post-COVID-19 respiratory symptoms (AOR 0.46; 95% CI, 0.22–0.97) but more post-COVID-19 cardiac symptoms among them (AOR 2.67; 95% CI, 1.26–5.65). Olfactory or taste disorders were fewer among patients infected in the Omicron period compared to the Wild-type period (AOR 0.14; 95% CI, 0.04–0.46).

Conclusion: This study revealed that symptoms after COVID-19 may vary depending on the infected strain.

Background: The novel coronavirus disease 2019 (COVID-19) pandemic may have reduced opportunities for engaging in physical activity (PA) and increased sedentary behavior (SB) among workers. However, most previous studies used self-reported assessments. This study aimed to examine the changes in accelerometer-measured PA and SB from before to after COVID-19 outbreak among Japanese workers.

Methods: This 1-year longitudinal study used data from the annual health check-ups of workers who lived in the Tokyo metropolitan area. Baseline and follow-up data were collected from June to November of 2019 and June to November of 2020, respectively. Participants were asked to wear the accelerometer on their hip during awake hours for at least 10 days in both the surveys. Before the analysis, considering the difference in wearing time, time spent in PA and SB were converted to the percentage of wearing time. To investigate the changes in PA or SB from before to during COVID-19 outbreak, paired t-tests were performed.

Results: Of the 757 eligible participants, 536 were included in the analysis (70.8%). Participants’ mean age was 53.3 years, 69.6% were female, and most were full-time employees. Time spent in PA decreased, regardless of weekdays or weekends, although changes on the weekends were not significant. Conversely, time spent in SB increased on both weekdays and weekends in 2020. These changes corresponded to approximately 10 minutes per day decrease in PA and increase in SB.

Conclusion: Objectively measured PA decreased and SB increased by approximately 10 minutes per day after the COVID-19 outbreak among Japanese workers.

In an aging society, it is important to visualize the conditions of people living with diseases or disabilities, such as frailty and sarcopenia, and determine the environmental and genetic factors underlying such conditions. Atherosclerosis and arterial stiffness are key conditions between these factors and noncommunicable diseases. In 2014, we launched a population-based prospective open-cohort study, the Nagasaki Islands Study (NaIS), which was conducted in Goto City, located in the remote islands of Nagasaki Prefecture, Japan, mostly involving middle-aged and older residents. We conducted our own health checkups along with the annual standardized checkups organized by the municipality; recruited study participants; and started to follow them for vital status (death), migration, and occurrence of diseases, such as myocardial infarction, stroke, fracture, and human T-cell leukemia virus type 1 (HTLV-1)-associated uveitis. Our checkups were conducted as baseline surveys in different areas of Goto City during the fiscal years 2014–2016, secondary surveys during 2017–2019, and tertiary surveys since 2021, consisting of medical interviews, physical examinations, blood and urine tests, body composition measurements, osteoporosis screening, arterial stiffness measurements, carotid ultrasonography, and dental examination. A total of 4,957 residents participated in either the baseline or secondary surveys and were followed; 3,594 and 3,364 residents (aged 27–96 and 28–98 years) participated in the baseline and secondary surveys, respectively. In conclusion, the NaIS has been undertaken to reveal the influence of aging and risk factors of noncommunicable diseases and disabilities, with an aim to contribute towards better healthcare in the future.