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  1. AU="Kimberlyn Roosa"
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  1. Article ; Online: Assessing parameter identifiability in compartmental dynamic models using a computational approach

    Kimberlyn Roosa / Gerardo Chowell

    Theoretical Biology and Medical Modelling, Vol 16, Iss 1, Pp 1-

    application to infectious disease transmission models

    2019  Volume 15

    Abstract: Abstract Background Mathematical modeling is now frequently used in outbreak investigations to understand underlying mechanisms of infectious disease dynamics, assess patterns in epidemiological data, and forecast the trajectory of epidemics. However, ... ...

    Abstract Abstract Background Mathematical modeling is now frequently used in outbreak investigations to understand underlying mechanisms of infectious disease dynamics, assess patterns in epidemiological data, and forecast the trajectory of epidemics. However, the successful application of mathematical models to guide public health interventions lies in the ability to reliably estimate model parameters and their corresponding uncertainty. Here, we present and illustrate a simple computational method for assessing parameter identifiability in compartmental epidemic models. Methods We describe a parametric bootstrap approach to generate simulated data from dynamical systems to quantify parameter uncertainty and identifiability. We calculate confidence intervals and mean squared error of estimated parameter distributions to assess parameter identifiability. To demonstrate this approach, we begin with a low-complexity SEIR model and work through examples of increasingly more complex compartmental models that correspond with applications to pandemic influenza, Ebola, and Zika. Results Overall, parameter identifiability issues are more likely to arise with more complex models (based on number of equations/states and parameters). As the number of parameters being jointly estimated increases, the uncertainty surrounding estimated parameters tends to increase, on average, as well. We found that, in most cases, R0 is often robust to parameter identifiability issues affecting individual parameters in the model. Despite large confidence intervals and higher mean squared error of other individual model parameters, R0 can still be estimated with precision and accuracy. Conclusions Because public health policies can be influenced by results of mathematical modeling studies, it is important to conduct parameter identifiability analyses prior to fitting the models to available data and to report parameter estimates with quantified uncertainty. The method described is helpful in these regards and enhances the essential toolkit for conducting model-based inferences using compartmental dynamic models.
    Keywords Compartmental models ; Parameter identifiability ; Uncertainty quantification ; Epidemic models ; Structural parameter identifiability ; Practical parameter identifiability ; Computer applications to medicine. Medical informatics ; R858-859.7 ; Biology (General) ; QH301-705.5
    Subject code 310
    Language English
    Publishing date 2019-01-01T00:00:00Z
    Publisher BMC
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Real-time monitoring the transmission potential of COVID-19 in Singapore, February 2020

    Amna Tariq / Yiseul Lee / Kimberlyn Roosa / Seth Blumberg / Ping Yan / Stefan Ma / Gerardo Chowell

    Abstract: The ongoing COVID-19 epidemic that spread widely in China since December 2019 is now generating local transmission in multiple countries including Singapore as of March 5, 2020. This highlights the need to monitor in real time the transmission potential ... ...

    Abstract The ongoing COVID-19 epidemic that spread widely in China since December 2019 is now generating local transmission in multiple countries including Singapore as of March 5, 2020. This highlights the need to monitor in real time the transmission potential of COVID-19. In Singapore, four major COVID-19 case clusters have emerged thus far. Here we estimate the effective reproduction number, Rt, of COVID-19 in Singapore from the publicly available daily case series of imported and autochthonous cases by date of symptoms onset, after adjusting the local cases for reporting delays. We also derive the reproduction number from the distribution of cluster sizes using a branching process analysis. The effective reproduction number peaked with a mean value ~1.0 around February 6-12, 2020 and declined thereafter. As of March 5, 2020, our most recent estimate of Rt is at 0.9 (95% CI: 0.7,1.0) while an estimate of the overall R based on cluster size distribution is at 0.7 (95% CI: 0.5, 1.0). The trajectory of the reproduction number in Singapore underscore the significant effects of containment efforts in Singapore while at the same time suggest the need to sustain social distancing and active case finding efforts to stomp out all active chains of transmission.
    Keywords covid19
    Publisher medrxiv
    Document type Article ; Online
    DOI 10.1101/2020.02.21.20026435
    Database COVID19

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  3. Article ; Online: Real-time monitoring the transmission potential of COVID-19 in Singapore, March 2020

    Amna Tariq / Yiseul Lee / Kimberlyn Roosa / Seth Blumberg / Ping Yan / Stefan Ma / Gerardo Chowell

    BMC Medicine, Vol 18, Iss 1, Pp 1-

    2020  Volume 14

    Abstract: Abstract Background As of March 31, 2020, the ongoing COVID-19 epidemic that started in China in December 2019 is now generating local transmission around the world. The geographic heterogeneity and associated intervention strategies highlight the need ... ...

    Abstract Abstract Background As of March 31, 2020, the ongoing COVID-19 epidemic that started in China in December 2019 is now generating local transmission around the world. The geographic heterogeneity and associated intervention strategies highlight the need to monitor in real time the transmission potential of COVID-19. Singapore provides a unique case example for monitoring transmission, as there have been multiple disease clusters, yet transmission remains relatively continued. Methods Here we estimate the effective reproduction number, R t , of COVID-19 in Singapore from the publicly available daily case series of imported and autochthonous cases by date of symptoms onset, after adjusting the local cases for reporting delays as of March 17, 2020. We also derive the reproduction number from the distribution of cluster sizes using a branching process analysis that accounts for truncation of case counts. Results The local incidence curve displays sub-exponential growth dynamics, with the reproduction number following a declining trend and reaching an estimate at 0.7 (95% CI 0.3, 1.0) during the first transmission wave by February 14, 2020, while the overall R based on the cluster size distribution as of March 17, 2020, was estimated at 0.6 (95% CI 0.4, 1.02). The overall mean reporting delay was estimated at 6.4 days (95% CI 5.8, 6.9), but it was shorter among imported cases compared to local cases (mean 4.3 vs. 7.6 days, Wilcoxon test, p < 0.001). Conclusion The trajectory of the reproduction number in Singapore underscores the significant effects of successful containment efforts in Singapore, but it also suggests the need to sustain social distancing and active case finding efforts to stomp out all active chains of transmission.
    Keywords SARS-CoV-2 ; COVID-19 ; Singapore ; Transmission potential ; Transmission heterogeneity ; Reproduction number ; Medicine ; R ; covid19
    Subject code 535
    Language English
    Publishing date 2020-06-01T00:00:00Z
    Publisher BMC
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Book ; Online: Short-term Forecasts of the COVID-19 Epidemic in Guangdong and Zhejiang, China

    Kimberlyn Roosa / Yiseul Lee / Ruiyan Luo / Alexander Kirpich / Richard Rothenberg / James M. Hyman / Ping Yan / Gerardo Chowell

    Journal of Clinical Medicine ; Volume 9 ; Issue 2

    February 13–23, 2020

    2020  

    Abstract: The ongoing COVID-19 epidemic continues to spread within and outside of China, despite several social distancing measures implemented by the Chinese government. Limited epidemiological data are available, and recent changes in case definition and ... ...

    Abstract The ongoing COVID-19 epidemic continues to spread within and outside of China, despite several social distancing measures implemented by the Chinese government. Limited epidemiological data are available, and recent changes in case definition and reporting further complicate our understanding of the impact of the epidemic, particularly in the epidemic’

    s epicenter. Here we use previously validated phenomenological models to generate short-term forecasts of cumulative reported cases in Guangdong and Zhejiang, China. Using daily reported cumulative case data up until 13 February 2020 from the National Health Commission of China, we report 5- and 10-day ahead forecasts of cumulative case reports. Specifically, we generate forecasts using a generalized logistic growth model, the Richards growth model, and a sub-epidemic wave model, which have each been previously used to forecast outbreaks due to different infectious diseases. Forecasts from each of the models suggest the outbreaks may be nearing extinction in both Guangdong and Zhejiang

    however, the sub-epidemic model predictions also include the potential for further sustained transmission, particularly in Zhejiang. Our 10-day forecasts across the three models predict an additional 65–

    81 cases (upper bounds: 169–

    507) in Guangdong and an additional 44–

    354 (upper bounds: 141–

    875) cases in Zhejiang by February 23, 2020. In the best-case scenario, current data suggest that transmission in both provinces is slowing down.
    Keywords COVID-19 ; coronavirus ; China ; real-time forecasts ; phenomenological models ; sub-epidemic model ; covid19
    Subject code 550
    Language English
    Publishing date 2020-02-22
    Publisher Multidisciplinary Digital Publishing Institute
    Publishing country ch
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Short-term Forecasts of the COVID-19 Epidemic in Guangdong and Zhejiang, China

    Kimberlyn Roosa / Yiseul Lee / Ruiyan Luo / Alexander Kirpich / Richard Rothenberg / James M. Hyman / Ping Yan / Gerardo Chowell

    Journal of Clinical Medicine, Vol 9, Iss 2, p

    February 13–23, 2020

    2020  Volume 596

    Abstract: The ongoing COVID-19 epidemic continues to spread within and outside of China, despite several social distancing measures implemented by the Chinese government. Limited epidemiological data are available, and recent changes in case definition and ... ...

    Abstract The ongoing COVID-19 epidemic continues to spread within and outside of China, despite several social distancing measures implemented by the Chinese government. Limited epidemiological data are available, and recent changes in case definition and reporting further complicate our understanding of the impact of the epidemic, particularly in the epidemic’s epicenter. Here we use previously validated phenomenological models to generate short-term forecasts of cumulative reported cases in Guangdong and Zhejiang, China. Using daily reported cumulative case data up until 13 February 2020 from the National Health Commission of China, we report 5- and 10-day ahead forecasts of cumulative case reports. Specifically, we generate forecasts using a generalized logistic growth model, the Richards growth model, and a sub-epidemic wave model, which have each been previously used to forecast outbreaks due to different infectious diseases. Forecasts from each of the models suggest the outbreaks may be nearing extinction in both Guangdong and Zhejiang; however, the sub-epidemic model predictions also include the potential for further sustained transmission, particularly in Zhejiang. Our 10-day forecasts across the three models predict an additional 65−81 cases (upper bounds: 169−507) in Guangdong and an additional 44−354 (upper bounds: 141−875) cases in Zhejiang by February 23, 2020. In the best-case scenario, current data suggest that transmission in both provinces is slowing down.
    Keywords covid-19 ; coronavirus ; china ; real-time forecasts ; phenomenological models ; sub-epidemic model ; Medicine ; R ; covid19
    Subject code 612
    Language English
    Publishing date 2020-02-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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