Abstract
Globally, the COVID-19 pandemic has induced a mental health crisis. Social media data offer a unique oppor-
tunity to track the mental health signals of a given population and quantify their negativity towards COVID-19.
To date, however, we know little about how negative sentiments differ across countries and how these relate to
the shifting policy landscape experienced through the pandemic. Using 2.1 billion individual-level geotagged
tweets posted between 1 February 2020 and 31 March 2021, we track, monitor and map the shifts in negativity
across 217 countries and unpack its relationship with COVID-19 policies. Findings reveal that there are important
geographic, demographic, and socioeconomic disparities of negativity across continents, different levels of a
nation’s income, population density, and the level of COVID-19 infection. Countries with more stringent policies
were associated with lower levels of negativity, a relationship that weakened in later phases of the pandemic.
This study provides the first global and multilingual evaluation of the public’s real-time mental health signals to
COVID-19 at a large spatial and temporal scale. We offer an empirical framework to monitor mental health
signals globally, helping international authorizations, including the United Nations and World Health Organi-
zation, to design smart country-specific mental health initiatives in response to the ongoing pandemic and future
public emergencies.