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As the COVID-19 epidemic continues, concerns about long-term health impacts, specifically long COVID, persist. While the prevalence and symptomatology of long COVID have been explored in various global contexts, large-scale cohort studies in Japan remain limited, especially after the advent of the Omicron variant. In this observational study, 4,047 residents with a history of COVID-19 living in Toyonaka City, Osaka Prefecture, were assessed for long COVID symptoms using the VOICE mobile application and a paper survey. Respondents provided demographic and health information, as well as information regarding COVID-19 infection and subsequent symptoms. A Cox proportional hazard regression model was used to estimate the multivariable-adjusted hazard ratios and 95 % confidence intervals for overall morbidity of long COVID symptoms. The survey found that 5.2 % of participants reported the persistence of one or more symptoms at 30 days post-onset. Fatigue was the most commonly reported symptom (1.75 %), followed by hair loss (1.41 %), and cough (1.28 %). Factors associated with an increased risk of experiencing long COVID symptoms included BMI, severe illness during the acute phase, and infection with certain COVID-19 variant strains, including Alpha, Delta, and Omicron. However, the incidence rate of long COVID appears to be decreasing with the dominance of the Omicron variant. This large-scale study from Toyonaka City suggests a 5.2 % prevalence rate for persistent COVID-19 symptoms 4 weeks post-infection, potentially indicating a lower prevalence of long COVID in Japanese populations after the rise of the Omicron variant. [ABSTRACT FROM AUTHOR]

Most of the currently used prognostic models for COVID-19 are based on Western cohorts, but it is unknown whether any are applicable to patients with COVID-19 in Japan. This retrospective cohort study included 160 patients with COVID-19 who were admitted to the National Center for Global Health and Medicine between January 26, 2020 and July 25, 2020. We searched PubMed for prognostic models for COVID-19. The predicted outcome was initiation of respiratory support or death. Performance of the candidate models was evaluated according to discrimination and calibration. We recalibrated the intercept of each model with our data. We also updated each model by adding β2-microglobulin (β2MG) to the model and recalculating the intercept and the coefficient of β2MG. Mean patient age was 49.8 years, 68% were male, 88.7% were Japanese. The study outcomes occurred in 15 patients, including two deaths. Two-hundred sixty-nine papers were screened, and four candidate prognostic models were assessed. The model of Bartoletti et al. had the highest area under receiver operating characteristic curve (AUC) (0.88; 95% confidence interval 0.81–0.96). All four models overestimated the probability of occurrence of the outcome. None of the four models showed statistically significant improvement in AUCs by adding β2MG. Our results suggest that the existing prediction models for COVID-19 overestimate the probability of occurrence of unfavorable outcomes in a Japanese cohort. When applying a prediction model to a different cohort, it is desirable to evaluate its performance according to the prevalent health situation in that region. [ABSTRACT FROM AUTHOR]

Various organizations and societies around the globe have issued guidelines in response to the coronavirus disease (COVID-19) and virus (SARS-CoV-2). In this paper, heating, ventilating, and air-conditioning-related guidelines or documents in several major countries and regions have been reviewed and compared, including those issued by the American Society of Heating Refrigerating and Air-Conditioning Engineers, the Federation of European Heating, Ventilation, and Air Conditioning Associations, the Society of Heating, Air-Conditioning and Sanitary Engineers of Japan, Architectural Society of China, and the Chinese Institute of Refrigeration. Most terms and suggestions in these guidelines are consistent with each other, although there are some conflicting details, reflecting the underlying uncertainty surrounding the transmission mechanism and characteristics of COVID-19 in buildings. All guidelines emphasize the importance of ventilation, but the specific ventilation rate that can eliminate the risk of transmission of airborne particulate matter has not been established. The most important countermeasure, commonly agreed countermeasures, the conflicting content from different guidelines, and further work have been summarized in this paper. [ABSTRACT FROM AUTHOR]