The COVID-19 pandemic had a significant impact on society. The United Nations (UN) warned of potential increases in the number of depressed patients and suicides. In Japan, child and adolescent suicides had been increasing even before the COVID-19 pandemic; however, as the UN predicted, the number of suicides increased significantly in 2020. Previous studies reported that mental illness is a risk factor for suicide, and it is a factor for suicide among children and adolescents. Shneidman and Joiner's models are widely supported as theoretical models of the psychology of suicide and are reported to be effective in understanding suicide among children and adolescents.
 During the COVID-19 pandemic, an expansion of social vulnerability was observed. Adolescents had increased social vulnerability due to "widening family poverty gap", "increased learning disparities", "dependence on the Internet and video games", "increased adverse childhood experiences", and "thwarted belongingness resulting from social distance and suppression of private speech". Other factors also increased social vulnerability. Under these circumstances, risk factors for suicide increased, and suicide increased. To prevent suicides among children and adolescents, it is important to educate supporters, train gatekeepers, and provide assessment and support by multiple professions.
 Author's abstract