During the early stages of the COVID-19 pandemic, a number of non-pharmaceutical interventions, particularly lockdowns (encompassing stay-at-home orders, curfews, quarantines, cordons sanitaires and similar societal restrictions), were implemented in numerous countries and territories around the world. By April 2020, about half of the world's population was under some form of lockdown, with more than 3.9 billion people in more than 90 countries or territories having been asked or ordered to stay at home by their governments. Although quarantines, similar to lockdowns, had been used in prior years, the massive and widespread scale of those mandatory lockdowns implemented in the early 2020s is thought to be unprecedented.
