Objective To evaluate the impact of the COVID-19 pandemic experience on language development among children, we compared language development at 18 months of age, before and during the pandemic in Japan, where strict control measures continued over a long period. Methods This was a repeated cross-sectional study and we included children who attended the 18-month health check-up provided by the Okayama City Public Health Center between January 2017 and December 2022 (n=33 484). We compared indicators of language development before (from January 2017 to February 2020) and during (from March 2020 to December 2022) the pandemic. Our primary outcome was the proportion of children who required follow-up for language development by the Public Health Center. The secondary outcome was the proportion of children who could not say three or more meaningful words. We estimated risk ratios (RRs) and their 95% CIs, adjusted for potential confounders. Results The prevalence of the primary outcome was 33.5% before the pandemic and 36% during the pandemic. Compared with before the pandemic, increased RRs for the primary and secondary outcomes were observed during the pandemic, with RRs (95% CIs) of 1.09 (1.06–1.13) for the primary outcome and 1.11 (1.05–1.17) for the secondary outcome. Although the statistical interactions were not significant, the RRs were higher for children cared for at home than those in nursery schools and with ≤3 family members than those with ≥4 family members. Conclusions The COVID-19 pandemic was associated with an increased risk of impaired language development in children at 18 months. More extensive support is needed for higher risk families, as well as follow-up of long-term language development in children affected by the COVID-19 pandemic.

AIM:The purpose of this study is to investigate the impact of abnormal blood pressure on the risk of all-cause and cardiovascular mortality in a large cohort of older Japanese people aged ≥65 years. METHODS:This cohort study enrolled 54 760 participants from Okayama City aged ≥65 years who underwent basic health checkups from April 2006 to March 2008. Based on blood pressure, the participants were divided into six categories, from C1 (lowest) to C6 (highest). To assess the association of blood pressure with all-cause and cardiovascular mortality, we used survival analysis to estimate hazard ratios (HRs) for all-cause mortality and subdistribution HRs (SHRs) for cardiovascular mortality on C3. We then repeated the analyses based on age groups (65-74 years, 75-84 years, and ≥85 years). RESULTS:The fully adjusted HRs for all-cause mortality, which included all individual potential confounders, were 1.11 (95% confidence interval [CI]: 1.04-1.19) for C5 and 1.23 (95% CI: 1.09-1.38) for C6, respectively. The fully adjusted SHRs for cardiovascular mortality were 1.11 (95% CI: 1.01-1.21) for C4, 1.19 (95% CI: 1.05-1.34) for C5, and 1.36 (95% CI: 1.09-1.70) for C6. In the age-stratification, an increased risk of hypotension was observed with older age. The HR for C1 was 1.28 (95% CI: 1.16-1.41) for ≥85 years. CONCLUSIONS:Hypertension increased the risk of all-cause and cardiovascular mortality among those aged 65-74 and 75-84 years, but not among those aged ≥85 years. Geriatr Gerontol Int 2025; 25: 82-89.

Introduction:In Japan, approximately 97 million individuals have received their primary two doses of coronavirus disease 2019 (COVID-19) vaccine at the end of 2022. In this study, we aim to examine the effectiveness of the primary vaccines and compare its efficacy to booster vaccine shots in terms of preventing COVID-19 exacerbations during the Omicron-predominant period in Japan.Methods:For this analysis, we have collected all the confirmed COVID-19-positive cases from different medical institutions in Okayama City and have also utilized the information from the public Vaccination Record System. Taking the number of vaccinations into consideration, we then conducted a population-based study to assess the effectiveness of the two primary vaccine doses in preventing COVID-19 exacerbations during the Omicron waves. Our primary and secondary outcomes were COVID-19 exacerbations with respiratory failure (i.e., oxygen saturation on room air ≤ 93%, requiring supplemental oxygen), intensive care unit admission and/or mechanical ventilator requirement, or death, in accordance with the Japanese COVID-19 guidelines, and pneumonia during the course of COVID-19 infection, respectively.Results:In total, 95,329 COVID-19-positive individuals, aged 5 years and above, were included in this analysis (study period from January 1 to September 10, 2022). As per our findings, the effectiveness of the primary two doses against COVID-19 exacerbations compared with those who had never been vaccinated was 55.5% (95% confidential interval [CI]: 32.6-71.7), whereas it was higher after the third dose (76.9%; 95% CI: 66.7-84.0) and the fourth dose (75.7%; 95% CI: 58.8-85.7). Effectiveness was sustained for ≥ 5 months after the third vaccination, and preventive effectiveness was observed in individuals aged ≥ 65 years.Conclusions:As per the results of this study, we can conclude that the efficacy of the primary two doses of SARS-CoV-2 vaccine can be further strengthened in terms of preventing COVID-19 exacerbations by administering third and fourth booster vaccine shots. The additional bivalent vaccine is anticipated to further increase its efficacy against the Omicron strain, suggesting that individuals who have not received their booster shots yet should consider getting them to prevent COVID-19 exacerbations.

Introduction: Obesity (i.e., body mass index [BMI] of 30 kg/m2 or more) is one of the risk factors for severe COVID-19, but the findings may not be directly applicable to Asians, who have a different cutoff point for defining obesity. We thus examined the association between obesity/overweight (BMI of 25 kg/m2 or more and less than 30 kg/m2) and the risk of COVID-19 severity.Methods: The study population included COVID-19 patients who had been enrolled in the registry of the Okayama City Public Health Center in Okayama, Japan, between March 2020 and June 2022. We included 27 820 patients who had information on BMI and prognosis, and we conducted Poisson regression analysis with robust error variance to estimate risk ratios (RRs) with 95% confidence intervals (CIs) for severe outcomes.Results: Obesity and overweight were associated with the increased risk of severe COVID-19 in all age categories. The RRs (95% CI) for COVID-19 induced respiratory failure compared to the normal weight category were 1.57 (1.31-1.88) for overweight and 2.45 (1.90-3.15) for obesity.Conclusions: Both obesity and overweight were associated with increased risk of severe COVID-19. This study suggests the importance of the overweight category to predict the risk of severe COVID-19 in Asians.

1Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan 2Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama, Japan 3Okayama University Health Service Center, Okayama, Japan 4Office of Innovative Medicine, Organization for Research Strategy and Development, Okayama University, Okayama, Japan 5Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama, Japan 6Clinical Laboratory, Okayama University Hospital, Okayama, Japan

BACKGROUNDIn aging societies, there is an increasing focus on the concept of frailty. However, there is no consistent means to assess this concept. We assessed frailty using the Kihon Checklist (KCL), which is widely used in Japan, and examined the association between frailty and all-cause and cause-specific mortality in Japan, the most aged society in the world.METHODSThis was a retrospective cohort study, and we analyzed 43,312 participants aged ≥ 65 years who were enrolled in basic health checkups in Okayama City, Japan. We defined the frailty status of the participants using the KCL. To assess the association of frailty status with all-cause and cause-specific mortality, we used cause-specific Cox proportional hazard models to estimate hazard ratios (HRs), adjusting for individual potential confounders. Mean follow-up time was 9.3 years.RESULTSThe fully adjusted HR for all-cause mortality was 1.34 (95% confidence interval [CI]: 1.27-1.41) for the prefrail group and 2.22 (95% CI: 2.11-2.33) for the frail group. A similar pattern was observed for cardiovascular disease, respiratory disease, and cancer mortality. Younger people (65-74 years) and women tended to have higher effect estimates than older people (≥ 75 years) and men.CONCLUSIONPrefrailty and frailty can increase the risk of both all-cause and cause-specific mortality. Our study suggests that to support frail patients, it could be effective to focus on the prevention and management of cardiovascular and respiratory disease, and that the KCL may be useful as a method of screening for frailty.

Background: Frailty is associated with the incidence of disability in older adults; however, few studies have investigated differences in the association of frailty with mild and severe disabilities according to Japanese long-term care insurance certification. This study separately investigated the associations between frailty and the incidence of mild and severe disabilities.Methods: This 3-year retrospective cohort study included community-dwelling adults in Okayama City aged ≥65 years. We assessed frailty status using the Kihon Checklist and defined the outcomes as mild and severe disabilities according to long-term care insurance certifications. We applied multinomial logistic regression analysis to investigate the association between frailty and the incidence of mild and severe disabilities.Results: The analysis included a total of 36,043 participants. For mild disability, the odds ratios (ORs) comparing frail to robust and prefrail to robust were 3.85 (95% confidence interval [CI], 3.36–4.42) and 1.82 (95% CI, 1.58–2.10), respectively. Similarly, the corresponding ORs for severe disability were 4.35 (95% CI, 3.55–5.34) and 1.78 (95% CI, 1.43–2.21), respectively. In the age-stratified analysis of mild disability, the pre-old group (aged 65–74 years) with frail showed a higher association than the old-age group (aged ≥75 years) with frail. Regarding severe disability, the older group with frailty showed a higher association than the pre-old group with frailty.Conclusion: The results showed that both prefrail and frail were associated with the incidence of mild and severe disabilities, with different patterns of association between the pre-old and old age groups.

The emergence of coronavirus disease 2019 (COVID-19) has catalyzed a new phase in vaccine development. 1Studies of the effectiveness of mRNA vaccines against COVID-19 have been conducted mainly in Western countries, and data from Asia are comparatively limited.Moreover, previous studies examined the effect of mRNA vaccines among uninfected individuals, but few studies have focused on severe outcomes among diagnosed patients.We examined the effect of mRNA vaccines in preventing COVID-19-related severe outcomes among patients in Japan.The study population were patients with COVID-19 aged 20 years and older reported to the Okayama City Public Health Center in Okayama City with symptom onset between July 1 and September 30, 2021.All patients were diagnosed with COVID-19 using polymerase chain reaction or antigen testing.For asymptomatic patients, the date of examination was used as the onset date.All cases occurring in Okayama City were reported to the center, and more than 90% of cases involved infection with the delta variant during the study period. 2Among the 3,616 cases reported to the center, we excluded teenagers and younger children because of low vaccination coverage and low risk of severe disease, leaving 2,882 adult patients.We assessed COVID-19 severity in these patients until October 14, 2021.The Public Health Center confirmed the vaccination status of patients and assessed COVID-19 severity in all patients and confirmed with the hospital when patients were hospitalized.We excluded a total of 174 patients with unknown vaccination status and 16 patients with unknown COVID-19 severity.Ultimately, a total of 2,692 patients remained in the final analysis.We classified the patients into three vaccination categories: fully vaccinated (≥14 days after the second dose), partially vaccinated (received only the first dose or <14 days after the second dose), or unvaccinated prior to symptom onset.During the study period, the only vaccines available in Okayama were the mRNA vaccines BNT162b2 and mRNA-1273.In keeping with the guidelines for COVID-19 in Japan, 3 we defined the primary outcome of our study as COVID-19 severe pneumonia with respiratory failure (eg, oxygen saturation [Sp0 2 ] on room air ≤93%, requiring supplemental oxygen), intensive care unit admission, mechanical intubation, and=or death.The secondary outcome was COVID-19 pneumonia diagnosed via imaging.

Amid the Coronavirus Disease 2019 pandemic, we aimed to demonstrate the accuracy of the fingertip whole blood sampling test (FWT) in measuring the antibody titer and uncovering its dynamics shortly after booster vaccination. Mokobio SARS-CoV-2 IgM & IgG Quantum Dot immunoassay (Mokobio Biotechnology R&D Center Inc., MD, USA) was used as a point-of-care FWT in 226 health care workers (HCWs) who had received two doses of the BNT162b2 mRNA vaccine (Pfizer-BioNTech) at least 8 months prior. Each participant tested their antibody titers before and after the third-dose booster up to 14-days. The effect of the booster was observed as early as the fourth day after vaccination, which exceeded the detection limit (> 30,000 U/mL) by 2.3% on the fifth day, 12.2% on the sixth day, and 22.5% after the seventh day. Significant positive correlations were observed between the pre- and post-vaccination (the seventh and eighth days) antibody titers (correlation coefficient, 0.405; p < 0.001). FWT is useful for examining antibody titers as a point-of-care test. Rapid response of antibody titer started as early as the fourth day post-vaccination, while the presence of weak responders to BNT162b2 vaccine was indicated.

Japan experienced four major epidemic periods (i.e., the 3rd-6th waves) of COVID-19 from January 2020 to March 2022. A different strain predominated in each period: the wild-type strain, an Alpha variant, a Delta variant, and an Omicron variant were predominant in waves 3, 4, 5, and 6, respectively. In this study, we conducted a descriptive analysis to investigate the differences in symptoms and severity during each epidemic period. We analyzed a total of 31,037 patients with COVID-19 who were reported to the Okayama City Public Health Center between February 1, 2020 and March 31, 2022. We described and compared the proportion of symptoms, the number and proportion of severe COVID-19 cases, and the number and proportion of deaths for each epidemic period. We also compared the proportion of severe COVID-19 cases depending on the number of vaccinations for the 5th and 6th waves. Differences in symptoms and severity were observed in each epidemic period. In the 5th and 6th waves, the results suggested that vaccination had a preventive effect against severe COVID-19.