A real-time survey on the psychological impact of mild lockdown for COVID-19 in the Japanese population

To deter the spread of the coronavirus disease 2019 (COVID-19), many countries have imposed a lockdown with restrictions. On 7 April 2020, the Japanese government declared a state of emergency over the COVID-19 outbreak. Japan was in mild lockdown which was not enforceable and non-punitive with the declaration. We conducted an online survey to investigate factors associated with psychological distress in the mild lockdown under a declared state of emergency for COVID-19. We collected data on 11,333 inhabitants (52.4% women, 46.3 +/- 14.6 years) living in the seven prefectures where the declaration was first applied. The investigation dates of this study, 11 and 12 May 2020, were in the final phase of the state of emergency. The survey was conducted in real-time to minimize participants' recall bias. In addition to psychological inventories often used worldwide, the questionnaires used in this survey included lifestyle and stress management items related to COVID-19 and various socio-demographic items including occupation (e.g. healthcare worker) or income.