Youth mental health before and after the control of the coronavirus disease 2019: A nationally representative cohort study of Chinese college students

•Chinese college students’ mental health improved after the control of COVID-19.•Nearly a half had psychological distress during the outbreak of COVID-19.•Around one-fourth had the same psychiatric disorders after new cases declined.•Over a half recovered while mental health problems persisted for nearly a half.•Public health policies should target high-risk cases with slower recovery.