The effect of control strategies that reduce social mixing on outcomes of the COVID-19 epidemic in Wuhan, China

Kiesha Prem; Yang Liu; Tim Russell; Adam J Kucharski; Rosalind M Eggo; Nicholas Davies; Mark Jit; Petra Klepac

The copyright holder for this preprint . https://doi.org/10.1101/2020.03.09.20033050 doi: medRxiv preprint social distancing interventions would need to be relaxed a month later (in April) in order to observe a larger effect. If children were less infectious as described in M2, lifting the social distancing interventions in April instead of March could have less additional health benefits (Fig 5B and 5D ). Mathematical models can help us understand how SARS-CoV-2 would spread across the population and inform control measures that may mitigate future transmission. 24, 25 Here, we simulated the trajectory of the ongoing outbreak of COVID-19 in Wuhan, using an age-structured SEIR model. 17, 18 Because individuals' mixing patterns are non-random, they influence the transmission dynamics of the disease. 11 Models assessing the effectiveness of social distancing interventions, such as school closure, need to account for social structures and heterogeneities in mixing of individuals. [26] [27] [28] [29] [30] In our model, we incorporated changes to age-and location-specific social mixing patterns to estimate the effects of location-specific social distancing interventions in curtailing the spread of the outbreak. Consequently, if these restrictions are lifted prematurely while there are still enough susceptibles to keep the . > 1 once contacts increase, the number of infections would increase. Realistically, interventions are lifted slowly, partly as an attempt to avoid a sharp increase in infection, but also for logistical and practical reasons. Therefore, lifting the interventions was simulated in a staggered fashion, whereby the interventions were relaxed bit-by-bit (Figures 3, 4 and 5) . Much remains to be discovered about the true age-specific susceptibility and transmissibility of COVID-19. Therefore, we assumed no heterogeneity in susceptibility between children. Furthermore, . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.