COVID-19 pandemic and language development in children at 18 months: a repeated cross-sectional study over a 6-year period in Japan.

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.

Effectiveness of the Original COVID-19 Vaccine against COVID-19 Exacerbations during the Omicron Wave: A Population-based Study in Okayama, Japan.

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.

Obesity, overweight, and severe prognosis in COVID-19 patients in Japan.

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.

Frailty and all-cause and cause-specific mortality in Japan.

BACKGROUND: In 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. METHODS: This 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. RESULTS: The 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. CONCLUSION: Prefrailty 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.

Differential Associations of Frailty with the Incidence of Mild and Severe Disabilities in Older Adults: A 3-Year Cohort Study.

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.

Early-stage antibody kinetics after the third dose of BNT162b2 mRNA COVID-19 vaccination measured by a point-of-care fingertip whole blood testing.

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.