Objective: This meta-analysis examines the psychological impact of COVID-19, SARS and MERS pandemics on health-care workers, patients and the general population, in line with PRISMA, MOOSE, MARS and CASP guidelines. Methods: Searches were conducted on 28-29 March 2020 in Pubmed, Medline, PsycInfo, APA articles, Web-of-Knowledge and scholar.google.com. Hedges’ g was calculated with random-effects models. Results: The final selection included 75 publications from 15,984 papers. Twenty-six studies described the impact of COVID-19 in 104,361 participants, showing that 59% (95%CI: 37%-85%) of health-care workers experienced acute/post-traumatic stress, and 37% (95%CI: 30%-54%) experienced depression, general distress, insomnia and/or anxiety. Of all COVID-19 patients, 32% (95% CI: 22%-42%) experienced acute/post-traumatic stress disorder, anxiety, depression, insomnia and/or distress. In the general population, 25% (95%CI: 15%-35%) experienced any of these psychological symptoms. COVID-19 had a larger impact than SARS/MERS in 28,499 participants in 44 studies. During SARS/MERS pandemics, 33% (95%CI: 25%-41%) of health-care workers, 31% (95%CI: 18%-45%) of SARS/MERS-patients and 15% (95%CI: 7%-23%) of the general population experienced any of these psychological symptoms. The psychological impact was predicted (R<.20-.40>) by the individual’s physical health, restrictions to leisure and social activities, and quarantine. Frontline health-care workers experienced a larger psychological impact than the general population, particularly if they worked with infected patients and reported unfavourable work circumstances. Conclusions: This study can be used to predict the prevalence of mental health problems during and after the COVID-19 pandemic, and to predict which individuals are most at risk of developing mental health problems. Health care workers and vulnerable individuals should be psychologically screened and offered mental health-care. Quarantine should be as short as possible, to prevent mental health problems. Public health significance statementThis meta-analysis indicates that between one-third of the general population and half of all health care workers experience a moderate to severe mental health impact of the COVID-19 pandemic. This impact is larger than during SARS and MERS pandemics. The psychological impact on health care workers is mainly predicted by their work circumstances, and the impact on the general population by their pre-existing physical and mental well-being and the psychological effects of quarantine.