Background: Coronavirus disease 2019 (COVID-19) pandemic are causing significant damages to many nations. For mitigating its risk, Japan’s Prime Minister called on all elementary, junior high and high schools nationwide to close beginning March 1, 2020. However, its effectiveness in decreasing disease burden has not been investigated. Methods: We used daily data on the report of COVID-19 and coronavirus infection incidence in Japan until March 31, 2020. Time series analysis were conducted using Bayesian method. Local linear trend models with interventional effect were constructed for number of newly reported cases of COVID-19, including asymptomatic infections. We considered that the effects of intervention start to appear 9 days after the school closure; i.e., on March 9. Results: The intervention of school closure did not appear to decrease the incidence of coronavirus infection. If the effectiveness of school closure began on March 9, mean coefficient α for effectiveness of the measure was calculated to be 0.08 (95% credible interval -0.36 to 0.65), and the actual reported cases were more than predicted, yet with rather wide credible interval. Sensitivity analyses using different dates also showed similar results. Conclusions: School closure carried out in Japan did not show the effectiveness to mitigate the transmission of novel coronavirus infection.

Highlights The effectiveness of school closure to mitigate the epidemic of COVID-19 remains unknown. Time series analyses were conducted using the Bayesian method to evaluate the effectiveness of school closure in Japan. The intervention of school closure did not appear to decrease the incidence of coronavirus infection.

Ongoing outbreak of pneumonia caused by novel coronavirus (2019-nCoV) began in December 2019 in Wuhan, China, and the number of new patients continues to increase. Even though it began to spread to many other parts of the world, such as other Asian countries, the Americas, Europe, and the Middle East, the impact of secondary outbreaks caused by exported cases outside China remains unclear. We conducted simulations to estimate the impact of potential secondary outbreaks in a community outside China. Simulations using stochastic SEIR model were conducted, assuming one patient was imported to a community. Among 45 possible scenarios we prepared, the worst scenario resulted in the total number of persons recovered or removed to be 997 (95% CrI 990-1000) at day 100 and a maximum number of symptomatic infectious patients per day of 335 (95% CrI 232-478). Calculated mean basic reproductive number (R 0 ) was 6.5 (Interquartile range, IQR 5.6-7.2). However, better case scenarios with different parameters led to no secondary cases. Altering parameters, especially time to hospital visit. could change the impact of a secondary outbreak. With these multiple scenarios with different parameters, healthcare professionals might be able to better prepare for this viral infection. Author Contributions: Conceptualization, K.I.; methodology, K.I. and C.M.; software, C.M.; validation, K.I.; writing-original draft preparation, K.I.; writing-review and editing, K.I. All authors have read and agreed to the published version of the manuscript. Funding: This research received no external funding. Conflicts of Interest:The authors declare no conflict of interest.

BackgroundEpidemiological studies in Kawasaki disease (KD) have suggested infectious aetiology. During the COVID-19 pandemic, measures for mitigating SARS-CoV-2 transmission also suppress the circulation of other contagious microorganisms. The primary objective is to compare the number and incidence of KD before and during the COVID-19 pandemic in Japan, and the secondary objective is to investigate temporal association between the KD epidemiology and activities of SARS-CoV-2 and other viral and bacterial infections.MethodsA retrospective cohort study was conducted between 2016 and 2020 in Kobe, Japan. We collected information of hospitalised KD children in Kobe. Child population was identified through the resident registry system. Activity of COVID-19 and 11 other infectious diseases was derived from a public health monitoring system. Monthly change of KD incidence was analysed using a difference-in-difference regression model.ResultsThroughout the study period, 1027 KD children were identified. KD had begun to decline in April 2020, coinciding with the beginning of the COVID-19 pandemic. The number of KD cases (n=66) between April and December 2020 was 40% of the average in the same period in 2016–2019 (165/year). Annual KD incidence was 315, 300, 353, 347 and 188/100 000 children aged 0–4 years in 2016–2020, respectively. The difference-in-difference value of KD incidence was significantly reduced in the fourth quarter in 2020 (−15.8, 95% CI −28.0 to −3.5), compared with that in 2016–2019. Sentinel surveillance showed a marked decrease of all infectious diseases except exanthema subitum after the beginning of the COVID-19 pandemic. There were 86 COVID-19 cases aged <10 years and no KD children associated with COVID-19.ConclusionThis study showed that the number and incidence of KD was dramatically reduced during the COVID-19 pandemic in Japan. This change was temporally associated with decreased activities of various infectious diseases other than COVID-19, supporting the hypothesis of infection-triggered pathogenesis in KD.

IMPORTANCE Despite intensive treatment, hospitalized patients with acute decompensated heart failure (ADHF) have a substantial risk of postdischarge mortality. Limited data are available on the possible differences in the incidence and mechanisms of death among patients with heart failure with reduced ejection fraction (HFrEF), heart failure with midrange ejection fraction (HFmrEF), and heart failure with preserved ejection fraction (HFpEF).OBJECTIVES To examine the incidences and mode of postdischarge mortality among patients with ADHF and to compare the risk profile among patients with HFrEF, HFmrEF, and HFpEF.