Effects of weather-related social distancing on city-scale transmission of respiratory viruses

Michael L Jackson; Gregory R Hart; Denise J McCulloch; Amanda Adler; Elisabeth Brandstetter; Kairsten Fay; Peter Han; Kirsten Lacombe; Jover Lee; Thomas Sibley; Deborah A Nickerson; Mark Rieder; Lea Starita; Janet A Englund; Trevor Bedford; Helen Chu; Michael Famulare

In the event of a pandemic caused by a novel respiratory virus, social distancing is one of the few effective interventions for reducing transmission and infection before vaccines or other prophylactic interventions become available. The potential impact and optimal timing of city-wide social distancing interventions to reduce the spread of influenza and other respiratory viruses are largely unknown. Most estimates of social distancing impact are limited to studies of school closures, including both routine holiday closures and reactive closures due to influenza epidemics. School closures may reduce rates of medically-attended influenza in school-aged children, although with highly heterogeneous effects (2% to 29% reductions), and with lesser effects on younger children and adults. [1] [2] [3] [4] [5] Generalizing to broader social distancing efforts from these studies is difficult, however, as school closures tend to have limited impacts on working-age and older adults, and school-aged children may recongregate outside of schools. 4, [6] [7] [8] In February 2019, unusually high snowfall in western Washington State led to widespread school and workplace closures and to reduced regional travel. This disruption of work and travel can be considered a proxy for social distancing that might accompany community-wide social mobility restrictions in the event of a pandemic. The objective of this study was to estimate the impact of this weather-created social distancing on transmission of respiratory viruses in the greater Seattle metropolitan area.