Effects of voluntary event cancellation and school closure as countermeasures against COVID-19 outbreak in Japan

Sugishita

et al. 2021

Preprint

Self Cite

Background: Strict countermeasures for COVID-19 outbreak such as lockdowns and voluntary restrictions against going out might have reduced mortality because of COVID-19 directly, but might have raised suicide rates. Object: We examined best policies for minimizing overall mortality attributable to COVID-19 directly, and excess mortality by suicide because of COVID-19. Method: We regressed the estimated excess mortality attributable to suicide deaths against mobility-restrictive measures. Mortality attributable to COVID-19 directly was estimated through association between the effective reproduction number and mobility. We sought the best mobility restriction for minimizing overall deaths. Results: Significant association was found between mobility and suicide, but the data were very few. Results showed the best mobility level as 65.5, which represents a 34.5% reduction in mobility from the normal level. Discussion and Conclusion: An overly restrictive policy inducing lower than optimal mobility led to higher total mortality.

Section: Methodsmentioning

confidence: 99%

“…All information used for this study was published on the web site of MHLW [1] and Japan Meteorological Agency [7]. Therefore, no ethical issue is presented.…”

Section: Ethical Considerationsmentioning

confidence: 99%

Optimal mobility restriction minimizing COVID-19 and excess suicide deaths in Japan

Kurita

Sugishita

et al. 2021

Preprint

Self Cite

“…The daily newly confirmed cases and information about severe cases in Osaka were published by the Osaka prefectural government [2]. Epidemic curves, which are newly onset patients by onset date, were calculated through empirical distribution of the incubation period and the reporting delay from onset to reporting, similarly to earlier studies [3, 4].…”

Section: Methodsmentioning

confidence: 99%

Prediction of severe COVID-19 cases requiring intensive care in Osaka, Japan

Kurita

Ohkusa

2021

Preprint

Self Cite

Background: To avoid exhaustion of medical resources by COVID-19 care, policy-makers must predict care needs, specifically estimating the proportion of severe cases likely to require intensive care. In Osaka prefecture, Japan, the number of these severe cases exceeded the capacity of ICU units prepared for COVID-19 from mid-April, 2021. Objective: This study used a statistical model to elucidate dynamics of severe cases in Osaka and validated the model through prospective testing. Methods: The study extended from April 3, 2020 through April 26, 2021 in Osaka prefecture, Japan prefecture. We regressed the number of severe cases on the number of severe cases the day prior and the newly onset patients of more than 21 days prior. Results: We selected the number of severe cases the day prior and the number of newly onset patients on 21 and 28 days prior as explanatory variables for explaining the number of severe cases based on the adjusted determinant coefficient. The adjusted coefficient of determination was greater than 0.995 and indicated good fit. Prospective out of sample three-week prediction forecast the peak date precisely, but the level was not t. Discussion and Conclusion: A reason for the gap in the prospective prediction might be the emergence of variant strains.

“…The copyright holder for this preprint this version posted June 22, 2021. ; https://doi.org/10.1101/2021.06.20.21259209 doi: medRxiv preprint were adjusted using the same procedures as those used for our earlier research [15,16].…”

Section: Onset Dates Among Patients Who Did Not Report This Information and Reporting Delaymentioning

confidence: 99%

Infectiousness in omicron variant strain and bA.2 variant in Japan

Kurita¹,

Ohkusa

2021

Preprint

Self Cite

Background: Japan started vaccinations for COVID-19 in late February, 2021, mainly using BNT162b2 mRNA COVID-19 Vaccine. Object: We evaluated COVID-19 vaccination effects on infectiousness in Japan. Method: The effective reproduction number R(t) was regressed on vaccine coverage along with data of temperature, humidity, mobility, and countermeasures. We presumed two definitions for vaccine coverage: at least a single dose with a 12-day delay and a second dose. The study period was February, 2020 through May 16, 2021. Results: Estimation results indicate that vaccine coverage significantly and drastically reduced R(t) for both definitions. Results imply that increased first shot coverage by 1% point decreased R(t) by 0.5 with a 12 day delay. Moreover, increased second shot coverage by 1% point, decreased R(t) by 1 immediately. Discussion and Conclusion: Vaccination effects might be stronger because the periods when vaccination was started and rapid spread coincide with a decreasing phase of R(t).