In response to the COVID-19 outbreak, Wuhan has undertaken a number of interventions, including extended school and workplace closures. The authors were interested in the effects of these physical distancing measures on the progression of the COVID-19 epidemic. They examined the synthetic location-specific contact patterns in Wuhan and adapted these in the presence of school closures, extended workplace closures and a reduction in mixing in the community. Based on these they simulated the ongoing trajectory of an outbreak in Wuhan using an age-structured susceptible-exposed-infected-removed (SEIR) model for several different measures. The authors also examined how a return to work should work. Their model suggests that physical distancing measures would be most effective if the staggered return to work was at the beginning of April. This reduced the median number of infections by more than 92% and 24% in mid-2020 and end-2020, respectively. Sustaining these measures until April would be beneficial in terms of delaying and reducing the height of the peak and median epidemic size at the end of 2020, and providing healthcare systems with more time to expand and respond. The modelled effects of physical distancing measures were sensitive to the duration of infectiousness and the role that school-age children have in the epidemic. Therefore the restrictions on activities in Wuhan, if maintained until April, will probably help to delay the epidemic peak. If the interventions are prematurely lifted then this could lead to an earlier secondary peak. This peak can be flattened by relaxing the interventions gradually.
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