Explaining the “Bomb-Like” Dynamics of COVID-19 with Modeling and the Implications for Policy

Lin, Gary; Bhaduri, Anindya; Strauss, Alexandra T.; Pinz, Maxwell; Martínez, Diego A.; Tseng, Katie K; Gaynor, Andrew T.; Hernández–Rivera, Efraín; Schueller, Emily; Gatalo, Oliver; Yang, Yanmei; Levin, Simon A.; Klein, Eili Y.

doi:10.1101/2020.04.05.20054338

Cited by 14 publications

(24 citation statements)

References 47 publications

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“…For instance, recent estimates point to asymptomatic infection accounting for around 20–30% of the total, with a similar percentage for pre-symptomatic infections [ 8 ]– together producing a majority. These findings have been supported by other experimental studies [ 9 ] and analysis of the existing data [ 10 , 11 ].…”

Section: Introductionsupporting

confidence: 83%

Optimal periodic closure for minimizing risk in emerging disease outbreaks

2021

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Without vaccines and treatments, societies must rely on non-pharmaceutical intervention strategies to control the spread of emerging diseases such as COVID-19. Though complete lockdown is epidemiologically effective, because it eliminates infectious contacts, it comes with significant costs. Several recent studies have suggested that a plausible compromise strategy for minimizing epidemic risk is periodic closure, in which populations oscillate between wide-spread social restrictions and relaxation. However, no underlying theory has been proposed to predict and explain optimal closure periods as a function of epidemiological and social parameters. In this work we develop such an analytical theory for SEIR-like model diseases, showing how characteristic closure periods emerge that minimize the total outbreak, and increase predictably with the reproductive number and incubation periods of a disease– as long as both are within predictable limits. Using our approach we demonstrate a sweet-spot effect in which optimal periodic closure is maximally effective for diseases with similar incubation and recovery periods. Our results compare well to numerical simulations, including in COVID-19 models where infectivity and recovery show significant variation.

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Section: Introductionsupporting

confidence: 83%

Optimal periodic closure for minimizing risk in emerging disease outbreaks

2021

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“… 18 This model is adapted from the Kermack and McKendrick compartmental model according to the disease dynamics that have been reported for COVID-19. The model assumptions are described in further depth in, 18 but in brief, we assume susceptible individuals who become infected have an incubation period; and some asymptomatic or mildly symptomatic individuals are neither tested nor counted as confirmed cases. Susceptible individuals, S , are those in the population that can become infected with the virus.…”

Section: Methodsmentioning

confidence: 99%

“…We assume that individuals who are asymptomatic or mildly symptomatic have a lower transmission rate, β 1 , than more symptomatic individuals, β 2 . 18 Exposed individuals incubate the virus at rate μ (calculated as the inverse of the incubation period). A proportion of these individuals, θ , becomes symptomatically infected while the rest become contagious with mild or no symptoms, C .…”

Section: Methodsmentioning

confidence: 99%

Modelling COVID-19 transmission in Africa: countrywise projections of total and severe infections under different lockdown scenarios

et al. 2021

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ObjectivesAs of 13 January 2021, there have been 3 113 963 confirmed cases of SARS-CoV-2 and 74 619 deaths across the African continent. Despite relatively lower numbers of cases initially, many African countries are now experiencing an exponential increase in case numbers. Estimates of the progression of disease and potential impact of different interventions are needed to inform policymaking decisions. Herein, we model the possible trajectory of SARS-CoV-2 in 52 African countries under different intervention scenarios.DesignWe developed a compartmental model of SARS-CoV-2 transmission to estimate the COVID-19 case burden for all African countries while considering four scenarios: no intervention, moderate lockdown, hard lockdown and hard lockdown with continued restrictions once lockdown is lifted. We further analysed the potential impact of COVID-19 on vulnerable populations affected by HIV/AIDS and tuberculosis (TB).ResultsIn the absence of an intervention, the most populous countries had the highest peaks in active projected number of infections with Nigeria having an estimated 645 081 severe infections. The scenario with a hard lockdown and continued post-lockdown interventions to reduce transmission was the most efficacious strategy for delaying the time to the peak and reducing the number of cases. In South Africa, projected peak severe infections increase from 162 977 to 2 03 261, when vulnerable populations with HIV/AIDS and TB are included in the analysis.ConclusionThe COVID-19 pandemic is rapidly spreading across the African continent. Estimates of the potential impact of interventions and burden of disease are essential for policymakers to make evidence-based decisions on the distribution of limited resources and to balance the economic costs of interventions with the potential for saving lives.

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“…2020. [17] Susceptible individuals, S , are those in the population that can become infected with the virus. They become exposed, E , to SARS-CoV-2 by encountering infected individuals in the population at rate β 1 for symptomatic individuals or β 2 for symptomatic individuals.…”

Section: Methodsmentioning

confidence: 99%

“…et al 2020 [17]. Susceptible individuals, S, are those in the population that can become infected with the virus.…”

mentioning

confidence: 99%

Modeling COVID-19 Transmission in Africa: Country-wise Projections of Total and Severe Infections Under Different Lockdown Scenarios

Frost

Craig

Osena

et al. 2020

Preprint

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Objectives As of August 24th 2020, there have been 1,084,904 confirmed cases of SARS-CoV-2 and 24,683 deaths across the African continent. Despite relatively lower numbers of cases initially, many African countries are now experiencing an exponential increase in case numbers. Estimates of the progression of disease and potential impact of different interventions are needed to inform policy making decisions. Herein, we model the possible trajectory of SARS-CoV-2 in 52 African countries under different intervention scenarios. Design We developed a compartmental model of SARS-CoV-2 transmission to estimate the COVID-19 case burden for all African countries while considering four scenarios: no intervention, moderate lockdown, hard lockdown, and hard lockdown with continued restrictions once lockdown is lifted. We further analyzed the potential impact of COVID-19 on vulnerable populations affected by HIV/AIDS and TB. Results In the absence of an intervention, the most populous countries had the highest peaks in active projected number of infections with Nigeria having an estimated 645,081 severe infections. The scenario with a hard lockdown and continued post-lockdown interventions to reduce transmission was the most efficacious strategy for delaying the time to the peak and reducing the number of cases. In South Africa projected peak severe infections increase from 162,977 to 203,261, when vulnerable populations with HIV/AIDS and TB are included in the analysis. Conclusion The COVID-19 pandemic is rapidly spreading across the African continent. Estimates of the potential impact of interventions and burden of disease are essential for policy makers to make evidence-based decisions on the distribution of limited resources and to balance the economic costs of interventions with the potential for saving lives.

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Explaining the “Bomb-Like” Dynamics of COVID-19 with Modeling and the Implications for Policy

Cited by 14 publications

References 47 publications

Optimal periodic closure for minimizing risk in emerging disease outbreaks

Optimal periodic closure for minimizing risk in emerging disease outbreaks

Modelling COVID-19 transmission in Africa: countrywise projections of total and severe infections under different lockdown scenarios

Modeling COVID-19 Transmission in Africa: Country-wise Projections of Total and Severe Infections Under Different Lockdown Scenarios

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