Social and physical distancing are key risk factors for mental health issues. Suicide, self-harm, depression, anxiety, alcohol and substance abuse are all expected to increase in crisis situations. The WHO issued on the 18th of March a document aiming to call attention to mental and psychosocial well-being of societies during the COVID-19 outbreak. A more recent WHO report, along with articles in the scientific literature, voice concerns that the world is likely to see an upsurge in mental illness and highlight the urgent need for research .

As of September 2020, more than 20,000 studies have been published about the impact of the pandemic on mental health. This number is expected to continue increasing rapidly in the near future, hence the importance of a living systematic review, that remains up-to-date in light of new evidence.

We hypothesize that the length and intensity of social isolation and the fear of infection can have important adverse effects on public mental health. However, large-scale evidence is lacking to-date to support or refute this claim. We currently do not know a) what is the prevalence of mental health issues in the general population and subpopulations worldwide during the COVID-19 pandemic, b) whether the intensity of the pandemic and the stridency of measures to contain the pandemic impact on mental health (and if yes, how) c) which population and context characteristics (e.g. sex, age, comorbidities, country) modify the impact of the pandemic on mental health.

We systematically review all studies published worldwide that evaluate the impact of the pandemic on public mental health. Volunteer trained researchers screen the literature and extract data on a weekly basis and we present regularly updated summaries of the prevalence of mental health issues during and before the pandemic by country and population. We also present the associations between the intensity of the outbreak (e.g., number of daily cases) and the containment measures (such as lockdown, stringency of social distancing rules) with changes in public mental health.

The chances of mounting a successful response to the possible effects of the pandemic on mental health depend on the speed and accuracy of analyzing available information. Hence, collecting relevant high-quality data is an immediate priority. Precise estimation of the increase in mental health problems during the pandemic is important in order to a) leverage the benefits and harms of containment measures (decreasing the infection rate versus exacerbating mental health problems) and b) design optimal interventions to prevent the harms of the containment measures. The continuous update of the evidence will help enable the Swiss Government or any other decision-making body to deploy a mental health science perspective to containment measures and set out immediate priorities and long-term strategies.