2.1.1. Survey procedure

We conducted an anonymous online survey named CORONA-CODOMO Survey (i.e., CODOMO means “children” in Japanese) from April 30th to May 31st. This survey targeted parents/guardians (“parents”) of children aged 0–17 years old and children aged 7–17 years old themselves. The survey was disseminated through a number of platforms, including the National Center for Child Health Development, child-related organizations, and social networking services (SNS). The questionnaire comprised two parts: one answered by parents about the health and current status of their children and themselves; the other answered by children aged 7 years or older. The study was approved by the institutional review board of the National Center for Child Health and Development (approval #2020-21).