The prevalence and risk factors of mental problems in medical students during COVID-19 pandemic: A systematic review and meta-analysis

•201 studies (N=198,000) from six databases were included.•COVID-19 increased prevalence of depression, anxiety, stress, distress, and suicidal ideation.•The pooled prevalence: depression (41%), anxiety (38%), stress (34%), sleep disorder (52%), psychological distress (58%), PTSD (34%), suicidal ideation (15%) and burnout (38%).•A range of risk factors at multiple levels were identified, most of which were reversible.•The results will help colleges and policymakers to provide targeted mental intervention.