The impact of social distancing, contact tracing, and case isolation interventions to suppress the COVID-19 epidemic: A modeling study

Abstract

Introduction Most countries are dependent on nonpharmaceutical public health interventions such as social distancing, contact tracing, and case isolation to mitigate COVID-19 spread until medicines or vaccines widely available. Minimal research has been performed on the independent and combined impact of each of these interventions based on empirical case data. Methods We obtained data from all confirmed COVID-19 cases from January 7 th to February 22 nd 2020 in Zhejiang Province, China, to fit an age-stratified compartmental model using human contact information before and during the outbreak. The effectiveness of social distancing, contact tracing, and case isolation was studied and compared in simulation. We also simulated a two-phase reopening scenario to assess whether various strategies combining nonpharmaceutical interventions are likely to achieve population-level control of a second-wave epidemic. Results Our study sample included 1,218 symptomatic cases with COVID-19, of which 664 had no inter-province travel history. Results suggest that 36.5% (95% CI, 12.8–57.1) of contacts were quarantined, and approximately five days (95% CI, 2.2–11.0) were needed to detect and isolate a case. As contact networks would increase after societal and economic reopening, avoiding a second wave without strengthening nonpharmaceutical interventions compared to the first wave it would be exceedingly difficult. Conclusions Continuous attention and further improvement of nonpharmaceutical interventions are needed in second-wave prevention. Specifically, contact tracing merits further attention.

Synchronized spread of COVID-19 in the cities of Bahia, Brazil

“…Once there is no treatment to combat the effects against SARS-CoV-2 virus. Besides early detection, non-pharmaceutical interventions (NPIs), such as hand hygiene, social distancing, facemask use and household quarantine are suggested to be more effective than travel restrictions at mitigating this pandemic ( Chinazzi et al, 2020 , Saunders-Hastings et al, 2017 , Jenness et al, 2021 , Ge et al, 2021 , Roche et al, 2020 , Flaxman et al, 2020 , Patiño-Lugo et al, 2020 ).…”

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“…Zhejiang province is an eastern coastal province adjacent to Shanghai city with a population of approximately 54 million individuals [ 29 ]. The first and only major wave of the COVID-19 epidemic in Zhejiang began on early January 2020 and continued until late February 2020 after which only sporadic single-case events were observed [ 30 , 31 ]. We included information from all confirmed cases in this major wave (a total of 1342 cases), as well as a follow-up investigation related to all detected asymptomatic infections to distinguish between asymptomatic and pre-symptomatic cases.…”

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“…The second group of individuals spread disease information in the society using the social media. [14] considered the impact of contact tracing, social distancing, and case isolation on the number of infections using a classical epidemiology model. [15] introduced an automated system that warns individuals who have faced others who have tested positive using their cell phones.…”