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  1. Article ; Online: Lifting mobility restrictions and the effect of superspreading events on the short-term dynamics of COVID-19.

    Santana-Cibrian, Mario / Acuña-Zegarra, Manuel A / Velasco-Hernandez, Jorge X

    Mathematical biosciences and engineering : MBE

    2020  Volume 17, Issue 5, Page(s) 6240–6258

    Abstract: SARS-CoV-2 has now infected 15 million people and produced more than six hundred thousand deaths around the world. Due to high transmission levels, many governments implemented social distancing and confinement measures with different levels of required ... ...

    Abstract SARS-CoV-2 has now infected 15 million people and produced more than six hundred thousand deaths around the world. Due to high transmission levels, many governments implemented social distancing and confinement measures with different levels of required compliance to mitigate the COVID-19 epidemic. In several countries, these measures were effective, and it was possible to flatten the epidemic curve and control it. In others, this objective was not or has not been achieved. In far too many cities around the world, rebounds of the epidemic are occurring or, in others, plateaulike states have appeared, where high incidence rates remain constant for relatively long periods of time. Nonetheless, faced with the challenge of urgent social need to reactivate their economies, many countries have decided to lift mitigation measures at times of high incidence. In this paper, we use a mathematical model to characterize the impact of short duration transmission events within the confinement period previous but close to the epidemic peak. The model also describes the possible consequences on the disease dynamics after mitigation measures are lifted. We use Mexico City as a case study. The results show that events of high mobility may produce either a later higher peak, a long plateau with relatively constant but high incidence or the same peak as in the original baseline epidemic curve, but with a post-peak interval of slower decay. Finally, we also show the importance of carefully timing the lifting of mitigation measures. If this occurs during a period of high incidence, then the disease transmission will rapidly increase, unless the effective contact rate keeps decreasing, which will be very difficult to achieve once the population is released.
    MeSH term(s) Algorithms ; Betacoronavirus ; COVID-19 ; Communicable Disease Control/legislation & jurisprudence ; Communicable Disease Control/methods ; Contact Tracing ; Coronavirus Infections/epidemiology ; Coronavirus Infections/transmission ; Health Behavior ; Humans ; Mexico/epidemiology ; Models, Theoretical ; Pandemics ; Pneumonia, Viral/epidemiology ; Pneumonia, Viral/transmission ; Probability ; Public Policy ; SARS-CoV-2 ; Social Isolation
    Keywords covid19
    Language English
    Publishing date 2020-10-29
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2265126-3
    ISSN 1551-0018 ; 1547-1063
    ISSN (online) 1551-0018
    ISSN 1547-1063
    DOI 10.3934/mbe.2020330
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Modeling behavioral change and COVID-19 containment in Mexico: A trade-off between lockdown and compliance.

    Acuña-Zegarra, Manuel Adrian / Santana-Cibrian, Mario / Velasco-Hernandez, Jorge X

    Mathematical biosciences

    2020  Volume 325, Page(s) 108370

    Abstract: Sanitary Emergency Measures (SEM) were implemented in Mexico on March 30th, 2020 requiring the suspension of non-essential activities. This action followed a Healthy Distance Sanitary action on March 23rd, 2020. The aim of both measures was to reduce ... ...

    Abstract Sanitary Emergency Measures (SEM) were implemented in Mexico on March 30th, 2020 requiring the suspension of non-essential activities. This action followed a Healthy Distance Sanitary action on March 23rd, 2020. The aim of both measures was to reduce community transmission of COVID-19 in Mexico by lowering the effective contact rate. Using a modification of the Kermack-McKendrick SEIR model we explore the effect of behavioral changes required to lower community transmission by introducing a time-varying contact rate, and the consequences of disease spread in a population subject to suspension of non-essential activities. Our study shows that there exists a trade-off between the proportion of the population under SEM and the average time an individual is committed to all the behavioral changes needed to achieve an effective social distancing. This trade-off generates an optimum value for the proportion of the population under strict mitigation measures, significantly below 1 in some cases, that minimizes maximum COVID-19 incidence. We study the population-level impact of three key factors: the implementation of behavior change control measures, the time horizon necessary to reduce the effective contact rate and the proportion of people under SEM in combating COVID-19. Our model is fitted to the available data. The initial phase of the epidemic, from February 17th to March 23rd, 2020, is used to estimate the contact rates, infectious periods and mortality rate using both confirmed cases (by date of symptoms initiation), and daily mortality. Data on deaths after March 23rd, 2020 is used to estimate the mortality rate after the mitigation measures are implemented. Our simulations indicate that the most likely dates for maximum incidence are between late May and early June, 2020 under a scenario of high SEM compliance and low SEM abandonment rate.
    MeSH term(s) COVID-19 ; Communicable Disease Control ; Coronavirus Infections/prevention & control ; Health Behavior ; Humans ; Mexico ; Models, Theoretical ; Pandemics/prevention & control ; Pneumonia, Viral/prevention & control ; Risk Reduction Behavior ; Social Isolation
    Keywords covid19
    Language English
    Publishing date 2020-05-06
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1126-5
    ISSN 1879-3134 ; 0025-5564
    ISSN (online) 1879-3134
    ISSN 0025-5564
    DOI 10.1016/j.mbs.2020.108370
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Transmission dynamics of acute respiratory diseases in a population structured by age.

    Arguedas, Yendry N / Santana-Cibrian, Mario / Velasco-Hernández, Jorge X

    Mathematical biosciences and engineering : MBE

    2019  Volume 16, Issue 6, Page(s) 7477–7493

    Abstract: Determining the role of age on the transmission of an infection is a topic that has received significant attention. In this work, a dataset of acute respiratory infections structured by age from San Luis Potosí, Mexico, is analyzed to understand the age ... ...

    Abstract Determining the role of age on the transmission of an infection is a topic that has received significant attention. In this work, a dataset of acute respiratory infections structured by age from San Luis Potosí, Mexico, is analyzed to understand the age impact on this class of diseases. To do that, a compartmental SEIRS multigroup model is proposed to describe the infection dynamics among age groups. Then, a Bayesian inference approach is used to estimate relevant parameters in the model such as the probability of infection, the average time that one individual remains infectious, the average time that one individual remains immune, and the force of infection, among others. Based on those estimates, our analysis leads us to conclude that children less than 5 years old are the primary spreaders of respiratory infections in San Luis Potosí's population from 2000 to 2008 since they are more prone to get sick, remain infectious for longer periods and they are reinfected more rapidly. On the other hand, the group of young adults (20-59) is the one that differs the most from the little children's group because it does not get sick often, it remains infectious only a few days and it stays healthy for longer periods. These observations allow us to infer that the group of young adults is the one that, on average, less contributed to the spread of this class of infections during the years represented in our database.
    MeSH term(s) Adolescent ; Adult ; Age Factors ; Aged ; Bayes Theorem ; Child ; Child, Preschool ; Communicable Disease Control ; Disease Outbreaks ; Disease Susceptibility ; Female ; Humans ; Infant ; Infant, Newborn ; Male ; Mexico/epidemiology ; Middle Aged ; Models, Statistical ; Population Dynamics ; Probability ; Respiratory Syncytial Virus Infections/transmission ; Respiratory Tract Infections/transmission ; Young Adult
    Language English
    Publishing date 2019-11-06
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2265126-3
    ISSN 1551-0018 ; 1547-1063
    ISSN (online) 1551-0018
    ISSN 1547-1063
    DOI 10.3934/mbe.2019375
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Flattening the curve and the effect of atypical events on mitigation measures in Mexico: a modeling perspective

    Santana-Cibrian, Mario / Acuna-Zegarra, Manuel Adrian / Velasco-Hernandez, Jorge X.

    Abstract: On 23 and 30 March 2020 the Mexican Federal government implemented social distancing measures to mitigate the COVID-19 epidemic. We use a mathematical model to explore atypical transmission events within the confinement period, triggered by the timing ... ...

    Abstract On 23 and 30 March 2020 the Mexican Federal government implemented social distancing measures to mitigate the COVID-19 epidemic. We use a mathematical model to explore atypical transmission events within the confinement period, triggered by the timing and strength of short time perturbations of social distancing. We show that social distancing measures were successful in achieving a significant reduction of the effective contact rate in the early weeks of the intervention. However, "flattening the curve" had an undesirable effect, since the epidemic peak was delayed too far, almost to the government preset day for lifting restrictions (01 June 2020). If the peak indeed occurs in late May or early June, then the events of children's day and mother's day may either generate a later peak (worst case scenario), a long plateau with relatively constant but high incidence (middle case scenario) or the same peak date as in the original baseline epidemic curve, but with a post-peak interval of slower decay.
    Keywords covid19
    Publisher MedRxiv; WHO
    Document type Article ; Online
    Note WHO #Covidence: #20109678
    DOI 10.1101/2020.05.21.20109678
    Database COVID19

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  5. Article: Lifting mobility restrictions and the effect of superspreading events on the short-term dynamics of COVID-19

    Santana-Cibrian, Mario / Acuña-Zegarra, Manuel A / Velasco-Hernandez, Jorge X

    Math Biosci Eng

    Abstract: SARS-CoV-2 has now infected 15 million people and produced more than six hundred thousand deaths around the world. Due to high transmission levels, many governments implemented social distancing and confinement measures with different levels of required ... ...

    Abstract SARS-CoV-2 has now infected 15 million people and produced more than six hundred thousand deaths around the world. Due to high transmission levels, many governments implemented social distancing and confinement measures with different levels of required compliance to mitigate the COVID-19 epidemic. In several countries, these measures were effective, and it was possible to flatten the epidemic curve and control it. In others, this objective was not or has not been achieved. In far too many cities around the world, rebounds of the epidemic are occurring or, in others, plateaulike states have appeared, where high incidence rates remain constant for relatively long periods of time. Nonetheless, faced with the challenge of urgent social need to reactivate their economies, many countries have decided to lift mitigation measures at times of high incidence. In this paper, we use a mathematical model to characterize the impact of short duration transmission events within the confinement period previous but close to the epidemic peak. The model also describes the possible consequences on the disease dynamics after mitigation measures are lifted. We use Mexico City as a case study. The results show that events of high mobility may produce either a later higher peak, a long plateau with relatively constant but high incidence or the same peak as in the original baseline epidemic curve, but with a post-peak interval of slower decay. Finally, we also show the importance of carefully timing the lifting of mitigation measures. If this occurs during a period of high incidence, then the disease transmission will rapidly increase, unless the effective contact rate keeps decreasing, which will be very difficult to achieve once the population is released.
    Keywords covid19
    Publisher WHO
    Document type Article
    Note WHO #Covidence: #869123
    Database COVID19

    Kategorien

  6. Article: Modeling behavioral change and COVID-19 containment in Mexico: A trade-off between lockdown and compliance

    Acuña-Zegarra, Manuel Adrian / Santana-Cibrian, Mario / Velasco-Hernandez, Jorge X

    Math Biosci

    Abstract: Sanitary Emergency Measures (SEM) were implemented in Mexico on March 30th, 2020 requiring the suspension of non-essential activities. This action followed a Healthy Distance Sanitary action on March 23rd, 2020. The aim of both measures was to reduce ... ...

    Abstract Sanitary Emergency Measures (SEM) were implemented in Mexico on March 30th, 2020 requiring the suspension of non-essential activities. This action followed a Healthy Distance Sanitary action on March 23rd, 2020. The aim of both measures was to reduce community transmission of COVID-19 in Mexico by lowering the effective contact rate. Using a modification of the Kermack-McKendrick SEIR model we explore the effect of behavioral changes required to lower community transmission by introducing a time-varying contact rate, and the consequences of disease spread in a population subject to suspension of non-essential activities. Our study shows that there exists a trade-off between the proportion of the population under SEM and the average time an individual is committed to all the behavioral changes needed to achieve an effective social distancing. This trade-off generates an optimum value for the proportion of the population under strict mitigation measures, significantly below 1 in some cases, that minimizes maximum COVID-19 incidence. We study the population-level impact of three key factors: the implementation of behavior change control measures, the time horizon necessary to reduce the effective contact rate and the proportion of people under SEM in combating COVID-19. Our model is fitted to the available data. The initial phase of the epidemic, from February 17th to March 23rd, 2020, is used to estimate the contact rates, infectious periods and mortality rate using both confirmed cases (by date of symptoms initiation), and daily mortality. Data on deaths after March 23rd, 2020 is used to estimate the mortality rate after the mitigation measures are implemented. Our simulations indicate that the most likely dates for maximum incidence are between late May and early June, 2020 under a scenario of high SEM compliance and low SEM abandonment rate.
    Keywords covid19
    Publisher WHO
    Document type Article
    Note WHO #Covidence: #186431
    Database COVID19

    Kategorien

  7. Article ; Online: Lifting mobility restrictions and the induced short-term dynamics of COVID-19

    Santana-Cibrian, Mario / Acuna-Zegarra, Manuel A. / Velasco-Hernandez, Jorge X.

    medRxiv

    Abstract: SARS-CoV-2 has now infected 15 million people and produced more than six hundred thousand deaths around the world. Due to high transmission levels, many governments implemented social-distancing measures and confinement with different levels of required ... ...

    Abstract SARS-CoV-2 has now infected 15 million people and produced more than six hundred thousand deaths around the world. Due to high transmission levels, many governments implemented social-distancing measures and confinement with different levels of required compliance to mitigate the COVID-19 epidemic. In several countries, these measures were effective, and it was possible to flatten the epidemic curve and control it. In others, this objective was not or has not been achieved. In far to many cities around the world rebounds of the epidemic are occurring or, in others, plateau-like states have appeared where high incidence rates remain constant for relatively long periods of time. Nonetheless, faced with the challenge of urgent social need to reactivate their economies, many countries have decided to lift mitigation measures at times of high incidence. In this paper, we use a mathematical model to characterize the impact of short duration transmission events within the confinement period previous but close to the epidemic peak. The model describes too, the possible consequences on the disease dynamics after mitigation measures are lifted. We use Mexico City as a case study. The results show that events of high mobility may produce either a later higher peak, a long plateau with relatively constant but high incidence or the same peak as in the original baseline epidemic curve, but with a post-peak interval of slower decay. Finally, we also show the importance of carefully timing the lifting of mitigation measures. If this occurs during a period of high incidence, then the disease transmission will rapidly increase, unless the effective contact rate keeps decreasing, which will be very difficult to achieve once the population is released.
    Keywords covid19
    Language English
    Publishing date 2020-07-24
    Publisher Cold Spring Harbor Laboratory Press
    Document type Article ; Online
    DOI 10.1101/2020.07.23.20161026
    Database COVID19

    Kategorien

  8. Article ; Online: Flattening the curve and the effect of atypical events on mitigation measures in Mexico: a modeling perspective

    Santana-Cibrian, Mario / Acuna-Zegarra, Manuel Adrian / Velasco-Hernandez, Jorge X.

    medRxiv

    Abstract: On 23 and 30 March 2020 the Mexican Federal government implemented social distancing measures to mitigate the COVID-19 epidemic. We use a mathematical model to explore atypical transmission events within the confinement period, triggered by the timing ... ...

    Abstract On 23 and 30 March 2020 the Mexican Federal government implemented social distancing measures to mitigate the COVID-19 epidemic. We use a mathematical model to explore atypical transmission events within the confinement period, triggered by the timing and strength of short time perturbations of social distancing. We show that social distancing measures were successful in achieving a significant reduction of the effective contact rate in the early weeks of the intervention. However, "flattening the curve" had an undesirable effect, since the epidemic peak was delayed too far, almost to the government preset day for lifting restrictions (01 June 2020). If the peak indeed occurs in late May or early June, then the events of children9s day and mother9s day may either generate a later peak (worst case scenario), a long plateau with relatively constant but high incidence (middle case scenario) or the same peak date as in the original baseline epidemic curve, but with a post-peak interval of slower decay.
    Keywords covid19
    Language English
    Publishing date 2020-05-23
    Publisher Cold Spring Harbor Laboratory Press
    Document type Article ; Online
    DOI 10.1101/2020.05.21.20109678
    Database COVID19

    Kategorien

  9. Article ; Online: Modeling behavioral change and COVID-19 containment in Mexico

    Acuña-Zegarra, Manuel Adrian / Santana-Cibrian, Mario / Velasco-Hernandez, Jorge X.

    Mathematical Biosciences

    A trade-off between lockdown and compliance

    2020  Volume 325, Page(s) 108370

    Keywords General Biochemistry, Genetics and Molecular Biology ; Modelling and Simulation ; Statistics and Probability ; General Immunology and Microbiology ; Applied Mathematics ; General Agricultural and Biological Sciences ; General Medicine ; covid19
    Language English
    Publisher Elsevier BV
    Publishing country us
    Document type Article ; Online
    ZDB-ID 1126-5
    ISSN 1879-3134 ; 0025-5564
    ISSN (online) 1879-3134
    ISSN 0025-5564
    DOI 10.1016/j.mbs.2020.108370
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  10. Article ; Online: A retrospective analysis of COVID-19 non-pharmaceutical interventions for Mexico and Peru: a modeling study

    Acuna-Zegarra, M. Adrian / Santana-Cibrian, Mario / Rodriguez Hernandez-Vela, Carlos E. / Mena, Ramses H. / Velasco-Hernandez, Jorge X.

    medRxiv

    Abstract: We model the observed dynamics of COVID-19 in Mexico and Peru and explore the impact of hypothetical non-pharmaceutical interventions applied on key days of civic, religious, or political nature that increased contacts and transmission events. Using as a ...

    Abstract We model the observed dynamics of COVID-19 in Mexico and Peru and explore the impact of hypothetical non-pharmaceutical interventions applied on key days of civic, religious, or political nature that increased contacts and transmission events. Using as a baseline the observed epidemic curve, we apply hypothetical reductions in the contact rates during the first year of the pandemic: i) near the beginning, ii) at the beginning of the second outbreak, and iii) end of the year. The effects of the interventions are different for Mexico and Peru but underlie the fact that strong early interventions do reduce the prevalence and, in general, allow for an epidemic evolution of relatively lower prevalence than interventions applied once the epidemic is underway. We provide evidence that key calendar days are good approximations of times when contact rates change and, therefore, are efficient periods for effective interventions particularly in places with low testing and lack of contact tracing. This has helped us to recreate different outbreaks of the COVID-19 disease dynamics in Mexico and Peru and explore the impact of hypothetical interventions that reduce the contact rate.
    Keywords covid19
    Language English
    Publishing date 2022-12-19
    Publisher Cold Spring Harbor Laboratory Press
    Document type Article ; Online
    DOI 10.1101/2022.12.19.22283668
    Database COVID19

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