During the pandemic, there has been ongoing and contentious debate around the impact of restrictive government measures to contain SARS-CoV-2 outbreaks, often termed ‘lockdowns’. We define a ‘lockdown’ as a highly restrictive set of non-pharmaceutical interventions against COVID-19, including either stay-at-home orders or interventions with an equivalent effect on movement in the population through restriction of movement. While necessarily broad, this definition encompasses the strict interventions embraced by many nations during the pandemic, particularly those that have prevented individuals from venturing outside of their homes for most reasons.