For decades, leading scientists and influential professional societies have warned of the dangers of emerging infections and the specter of a global pandemic.1,2 The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its subsequent spread has lived up to and surpassed many of the warnings and has caused an evolving global public health and economic crisis. Significantly, no pharmaceutical agents are known to be safe and effective at preventing or treating coronavirus disease 2019 (COVID-19), the resulting illness.3 This leaves the medical and public health community with only nonpharmaceutical interventions (NPIs) to rely on for reducing the burden of COVID-19. These measures aim to reduce disease transmission both locally and globally and include bans on public gatherings, compulsory stay-at-home policies, mandating closures of schools and nonessential businesses, face mask ordinances, quarantine and cordon sanitaire (ie, a defined quarantine area from which those inside are not allowed to leave), among others. The effectiveness of NPIs has been studied theoretically,4 especially within the context of pandemic influenza, and also through analysis of historical observational data.5- 7 A common finding of these studies is that implementing NPIs, especially when done rapidly after initial detection of a new contagious pathogen, can reduce transmission.