Early on, some airports installed thermal screening and others asked travellers to declare fever or respiratory symptoms at disembarkation. The utility of these interventions has been repeatedly challenged [16] , although if executed well could delay the start of community transmission by a few weeks [15, 17] (Table 2) . Similarly, during the early stages of global or local spread, quarantine, isolation, school closures, and other social distancing measures were variously implemented in some populations (e.g., Mexico [18] , western Japan [19] , UK), although most have not yet been formally evaluated and published [20] . Two exceptions are in Hong Kong and the UK. In the former, it was estimated that transmission fell by 25% when schools closed [21] . In settings like Hong Kong, with the infrastructure and resources to implement such measures and N Decisions regarding pandemic response during the exigencies of a public health emergency must be judged according to the best evidence available at the time.