Background: Countermeasures against COVID-19 outbreak, such as lockdowns and voluntary restrictions against going out, adversely affect human stress and depress economic activity. Particularly, this stress might lead to suicide. Object: We examined excess mortality attributable to COVID-19 related suicide. Method: We applied the National Institute of Infectious Diseases (NIID) model to suicide deaths, by gender, throughout Japan during October 2009–January 2021. Effects of the great earthquake that struck eastern Japan on March 11, 2011 were incorporated into the estimation model. Results: Significant excess mortality from suicide was found during July–January for both genders. Its frequency was higher among females than among males. In total, 2276 cases of excess mortality were identified. Discussion and Conclusion: Excess mortality during the four months was more than twice that of COVID-19 deaths confirmed by PCR testing. Countermeasures against COVID-19 should be chosen carefully in light of suicide effects.

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