17 Jul COVID-19: What Are the Limitations of Social Distancing?

MedicalResearch.com Interview with:

Dr. Chakrabarty

Rajan K. Chakrabarty, Ph.D.
Associate Professor,
Department of Energy, Environmental and Chemical Engineering
Washington University in Saint Louis

MedicalResearch.com: What is the background for this study?

Response: At the onset of COVID-19, we developed a state-of-the-art epidemic progression model involving the susceptible, exposed, infected, and recovered (SEIR) dynamics, the age-stratified disease transmissibility, and the possible large-scale undocumented asymptomatic transmission of COVID-19 taking place in the US states. By informing our model with using epidemiological COVID-19 data for the US between March 19 and 28 – a period corresponding to the early stage of the epidemic when the impacts of social distancing on disease progression were yet to manifest – we investigated: “What is the medical cost benefit of implementing social distancing as the “only” non-pharmaceutical intervention policy to combat COVID-19 in the US?”

As part of this study, we investigated three social distancing strategies – indefinite, finite-duration, and intermittent – on age-stratified US population and benchmark its effectiveness in reducing the burden on hospital beds.

MedicalResearch.com: What are the main findings?

Response: We find that a wholesale, indefinite social distancing could balance the demand-to-supply ratios of hospital beds at epidemic peaks provided a 70% percent reduction in the time-of-exposure of the population within all age-groups is achieved. The benefits of finite-duration social distancing manifests itself into two distinct regimes. For social distancing lasting less than two weeks, higher reduction in the time-of-exposure of the population results in less hospitalizations. For social distancing lasting longer than two weeks, ~50% reduction in the time-of-exposure of the population yields the largest reduction in hospitalizations. Greater than this threshold reduction intensity, our analysis shows a large buildup of susceptible individuals, who remain prone to the infection at the end of the social distancing period.

Overall, we emphasize the exponentially diminishing medical cost benefits of finite-duration social distancing–a phenomenon characterized by a linear decrease in medical demand achieved against an exponentially increasing social distancing duration. We finally investigated intermittent social distancing as a strategy to circumvent this situation, and find a critical intermittent social- to no-distancing duration ratio of 5:1, which facilitates up to 80% percent reduction in medical demands. Exceeding this critical ratio, the marginal benefit of social distancing wanes 

MedicalResearch.com: What should readers take away from your report?

Response: Social distancing as a whole-of-government approach cannot be successful without the tandem implementation of wide-spread testing, contact tracing, and isolation of those found to be infected. The non-linear dynamics between social distancing and hospitalization-demand emphasize that precautions need to be taken when lifting strict social distancing measures abruptly, so as to prevent the onset of second wave of infection. Aggressive contact tracing and isolation are necessary for identifying and isolating the COVID-19 carriers from a potential large susceptible pool of the population.

MedicalResearch.com: What recommendations do you have for future research as a result of this work?

Response: Future research needs to be conducted in modeling the effectiveness of tandem implementation of social distancing, contact tracing and isolation on an age-stratified population. Infectious disease transmission and control is a complex systems science involving many variables interacting at the same time. A system level understanding of different modes of disease prevention is necessary from the public health and policy standpoint. 

The authors of this work declare no competing interests. 

Citation:

Pai Liu, Payton Beeler, Rajan K. Chakrabarty.Dynamic interplay between social distancing duration and intensity in reducing COVID-19 US hospitalizations: A “law of diminishing returns”. Chaos: An Interdisciplinary Journal of Nonlinear Science, 2020; 30 (7): 071102 DOI: 10.1063/5.0013871

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Last Updated on July 17, 2020 by Marie Benz MD FAAD