The COVID-19 pandemic has led to world-wide human suffering, which may include negative effects on mental health (United Nations, 2020). A great number of research projects have assessed the mental health impacts of COVID-19, which have been integrated into systematic reviews (SRs) with or without meta-analyses (MAs). Although some authors have reported direct and indirect negative effects of COVID-19 on specific mental health problems (e.g., depression or post-traumatic stress symptoms) and elevated generic psychological distress due to pandemic control measures (e.g., Dong et al., 2021; Xiong et al., 2020), other population-based studies indicated that most people are resilient and do not experience an increase in distress despite exposure to stressors (Pierce et al., 2021). Generally, findings from SRs and MAs are inconsistent and highly diverse in quality. Hence, proper understanding of the evidence on the impacts of COVID-19 on mental health is needed to correctly inform the global mental health response and to identify gaps in knowledge for further scientific research. The aim of this umbrella review is to synthesize the existing evidence of the impact of COVID-19 on mental health. To this end, the proposed umbrella review will answer the following questions: (1) What is the impact of COVID-19 on prevalence of mental health symptoms and mental health disorders among the general population, health care workers, and vulnerable groups and what is the mental health impact of COVID-19 over time during the pandemic? (2) What is the impact of COVID-19 on suicidal behaviour and suicidal thoughts prevalence in any population? (3) Are people living with pre COVID-19 existing mental health disorders at (increased) risk of severe illness and mortality and/or of contracting SARS-CoV-2 compared to any other population? (4) What is the impact of COVID-19 on access and delivery of mental health services and how have mental health services changed during the pandemic? (5a) What is the effectiveness of psychological interventions aimed to prevent and reduce mental health problems (depression, anxiety, posttraumatic stress, substance use, suicidal behaviours) and improve well-being and resilience related to COVID-19 and the epidemic control measures? (5b) What is the effectiveness of psychological interventions and strategies adapted to be delivered during the COVID-19 pandemic compared to psychological interventions as usual on the reduction of mental health problems and on access to mental health services during the pandemic?
