Basic Reproduction Number

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Grace Y Yi - One of the best experts on this subject based on the ideXlab platform.

Wenqing He - One of the best experts on this subject based on the ideXlab platform.

Anthony J Parolari - One of the best experts on this subject based on the ideXlab platform.

  • global convergence of covid 19 Basic Reproduction Number and estimation from early time sir dynamics
    PLOS ONE, 2020
    Co-Authors: Gabriel G Katul, Assaad Mrad, Sara Bonetti, Gabriele Manoli, Anthony J Parolari
    Abstract:

    The SIR ('susceptible-infectious-recovered') formulation is used to uncover the generic spread mechanisms observed by COVID-19 dynamics globally, especially in the early phases of infectious spread. During this early period, potential controls were not effectively put in place or enforced in many countries. Hence, the early phases of COVID-19 spread in countries where controls were weak offer a unique perspective on the ensemble-behavior of COVID-19 Basic Reproduction Number Ro inferred from SIR formulation. The work here shows that there is global convergence (i.e., across many nations) to an uncontrolled Ro = 4.5 that describes the early time spread of COVID-19. This value is in agreement with independent estimates from other sources reviewed here and adds to the growing consensus that the early estimate of Ro = 2.2 adopted by the World Health Organization is low. A reconciliation between power-law and exponential growth predictions is also featured within the confines of the SIR formulation. The effects of testing ramp-up and the role of 'super-spreaders' on the inference of Ro are analyzed using idealized scenarios. Implications for evaluating potential control strategies from this uncontrolled Ro are briefly discussed in the context of the maximum possible infected fraction of the population (needed to assess health care capacity) and mortality (especially in the USA given diverging projections). Model results indicate that if intervention measures still result in Ro > 2.7 within 44 days after first infection, intervention is unlikely to be effective in general for COVID-19.

  • global convergence of covid 19 Basic Reproduction Number and estimation from early time sir dynamics
    medRxiv, 2020
    Co-Authors: Gabriel G Katul, Assaad Mrad, Sara Bonetti, Gabriele Manoli, Anthony J Parolari
    Abstract:

    Abstract The SIR (‘susceptible-infectious-recovered’) formulation is used to uncover the generic spread mechanisms observed by COVID-19 dynamics globally, especially in the early phases of infectious spread. During this early period, potential controls were not effectively put in place or enforced in many countries. Hence, the early phases of COVID-19 spread in countries where controls were weak offer a unique perspective on the ensemble-behavior of COVID-19 Basic Reproduction Number Ro. The work here shows that there is global convergence (i.e. across many nations) to an uncontrolled Ro = 4.5 that describes the early time spread of COVID-19. This value is in agreement with independent estimates from other sources reviewed here and adds to the growing consensus that the early estimate of Ro = 2.2 adopted by the World Health Organization is low. A reconciliation between power-law and exponential growth predictions is also featured within the confines of the SIR formulation. Implications for evaluating potential control strategies from this uncontrolled Ro are briefly discussed in the context of the maximum possible infected fraction of the population (needed for assessing health care capacity) and mortality (especially in the USA given diverging projections). Model results indicate that if intervention measures still result in Ro> 2.7 within 49 days after first infection, intervention is unlikely to be effective in general for COVID-19. Current optimistic projections place mortality figures in the USA in the range of 100,000 fatalities. For fatalities to be confined to 100,000 requires a reduction in Ro from 4.5 to 2.7 within 17 days of first infection assuming a mortality rate of 3.4%.

Hyukjun Chang - One of the best experts on this subject based on the ideXlab platform.

  • estimation of Basic Reproduction Number of the middle east respiratory syndrome coronavirus mers cov during the outbreak in south korea 2015
    Biomedical Engineering Online, 2017
    Co-Authors: Hyukjun Chang
    Abstract:

    Background In South Korea, an outbreak of Middle East respiratory syndrome (MERS) occurred in 2015. It was the second largest MERS outbreak. As a result of the outbreak in South Korea, 186 infections were reported, and 36 patients died. At least 16,693 people were isolated with suspicious symptoms. This paper estimates the Basic Reproduction Number of the MERS coronavirus (CoV), using data on the spread of MERS in South Korea.

  • estimation of Basic Reproduction Number of the middle east respiratory syndrome coronavirus mers cov during the outbreak in south korea 2015
    Biomedical Engineering Online, 2017
    Co-Authors: Hyukjun Chang
    Abstract:

    In South Korea, an outbreak of Middle East respiratory syndrome (MERS) occurred in 2015. It was the second largest MERS outbreak. As a result of the outbreak in South Korea, 186 infections were reported, and 36 patients died. At least 16,693 people were isolated with suspicious symptoms. This paper estimates the Basic Reproduction Number of the MERS coronavirus (CoV), using data on the spread of MERS in South Korea. The Basic Reproduction Number of an epidemic is defined as the average Number of secondary cases that an infected subject produces over its infectious period in a susceptible and uninfected population. To estimate the Basic Reproduction Number of the MERS-CoV, we employ data from the 2015 South Korea MERS outbreak and the susceptible-infected-removed (SIR) model, a mathematical model that uses a set of ordinary differential equations (ODEs). We fit the model to the epidemic data of the South Korea outbreak minimizing the sum of the squared errors to identify model parameters. Also we derive the Basic reproductive Number as the terms of the parameters of the SIR model. Then we determine the Basic Reproduction Number of the MERS-CoV in South Korea in 2015 as 8.0977. It is worth comparing with the Basic reproductive Number of the 2014 Ebola outbreak in West Africa including Guinea, Sierra Leone, and Liberia, which had values of 1.5–2.5. There was no intervention to control the infection in the early phase of the outbreak, thus the data used here provide the best conditions to evaluate the epidemic characteristics of MERS, such as the Basic Reproduction Number. An evaluation of Basic Reproduction Number using epidemic data could be problematic if there are stochastic fluctuations in the early phase of the outbreak, or if the report is not accurate and there is bias in the data. Such problems are not relevant to this study because the data used here were precisely reported and verified by Korea Hospital Association.

P S Mellor - One of the best experts on this subject based on the ideXlab platform.

  • assessing the risk of bluetongue to uk livestock uncertainty and sensitivity analyses of a temperature dependent model for the Basic Reproduction Number
    Journal of the Royal Society Interface, 2008
    Co-Authors: Simon Gubbins, Simon Carpenter, Matthew Baylis, J L N Wood, P S Mellor
    Abstract:

    Since 1998 bluetongue virus (BTV), which causes bluetongue, a non-contagious, insect-borne infectious disease of ruminants, has expanded northwards in Europe in an unprecedented series of incursions, suggesting that there is a risk to the large and valuable British livestock industry. The Basic Reproduction Number, R0, provides a powerful tool with which to assess the level of risk posed by a disease. In this paper, we compute R0 for BTV in a population comprising two host species, cattle and sheep. Estimates for each parameter which influences R0 were obtained from the published literature, using those applicable to the UK situation wherever possible. Moreover, explicit temperature dependence was included for those parameters for which it had been quantified. Uncertainty and sensitivity analyses based on Latin hypercube sampling and partial rank correlation coefficients identified temperature, the probability of transmission from host to vector and the vector to host ratio as being most important in determining the magnitude of R0. The importance of temperature reflects the fact that it influences many processes involved in the transmission of BTV and, in particular, the biting rate, the extrinsic incubation period and the vector mortality rate.

  • vector borne diseases and the Basic Reproduction Number a case study of african horse sickness
    Medical and Veterinary Entomology, 1996
    Co-Authors: Cynthia C Lord, J A P Heesterbeek, Mark E J Woolhouse, P S Mellor
    Abstract:

    The Basic Reproduction Number, R0, can be used to determine factors important in the ability of a disease to invade or persist. We show how this Number can be derived or estimated for vector-borne diseases with different complicating factors. African horse sickness is a viral disease transmitted mainly by the midge Culicoides imicola. We use this as an example of such a vector-transmitted disease where latent periods, seasonality in vector populations, and multiple host types may be important. The effect of vector population dynamics which are dependent on either host or vector density are also addressed. If density-dependent constraints on vector population density are less severe, R0 is more sensitive to vector mortality and the virus development rate. Host-dependent vector dynamics change the relationship between R0 and host population size. Seasonality can either increase or decrease the estimate of R0, depending on the lag between the peak of the midge population and the infective host population. The relative abundance of two host types is a factor in the ability of a disease to invade, but the strength of this factor depends on the differences between the hosts in recovery from infection, mortality and transmission. Removal of a reservoir host may increase R0.

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