scholarly journals A flexible COVID-19 model to assess mitigation, reopening, virus mutation and other changes

2020 ◽  
Author(s):  
Sergio Bienstock
Keyword(s):  
Resource Allocation ◽  
Epidemiological Model ◽  
Mitigation Strategies ◽  
Time Dependent ◽  
Reproduction Ratio ◽  
Social Distancing ◽  
The Impact ◽  
Economic Tradeoffs ◽  
Daily Changes ◽  
Future Date

The COVID-19 epidemic which began in China last year has expanded worldwide. A flexible SEIRD epidemiological model with time-dependent parameters is applied to modeling the pandemic. The value of the effective reproduction ratio is varied to quantify the impact of quarantines and social distancing on the number of infections and deaths, on their daily changes. and on the maxima in these daily rates expected during the epidemic. The effect of changing Reff is substantial. It ought to inform policy decisions around resource allocation, mitigation strategies and their duration, and economic tradeoffs. The model can also calculate the impact of changes in infectiousness or morbidity as the virus mutates, or the expected effects of a new therapy or vaccine assumed to arrive at a future date. The paper concludes with a discussion of a potential endemic end of COVID-19, which might involve times of about 100 years.

scholarly journals Stochastic simulation of successive waves of COVID-19 in the province of Barcelona

2021 ◽  
Author(s):  
M. Bosman ◽  
A. Esteve ◽  
L. Gabbanelli ◽  
X. Jordan ◽  
A. López-Gay ◽  
...  
Keyword(s):  
Compartmental Model ◽  
Stochastic Approach ◽  
Mitigation Strategies ◽  
Time Dependent ◽  
Population Census ◽  
Mathematical Epidemiology ◽  
The Social ◽  
Age Dependent ◽  
Dynamical Features ◽  
The Impact

AbstractAnalytic compartmental models are currently used in mathematical epidemiology to forecast the COVID-19 pandemic evolution and explore the impact of mitigation strategies. In general, such models treat the population as a single entity, losing the social, cultural and economical specifici- ties. We present a network model that uses socio-demographic datasets with the highest available granularity to predict the spread of COVID-19 in the province of Barcelona. The model is flexible enough to incorporate the effect of containment policies, such as lockdowns or the use of protec- tive masks, and can be easily adapted to future epidemics. We follow a stochastic approach that combines a compartmental model with detailed individual microdata from the population census, including social determinants and age-dependent strata, and time-dependent mobility information. We show that our model reproduces the dynamical features of the disease across two waves and demonstrate its capability to become a powerful tool for simulating epidemic events.

scholarly journals The effectiveness of interventions to reduce COVID-19 transmission in a large urban jail

2020 ◽  
Author(s):  
Giovanni S. P. Malloy ◽  
Lisa Puglisi ◽  
Margaret L. Brandeau ◽  
Tyler D. Harvey ◽  
Emily A. Wang
Keyword(s):  
Single Cells ◽  
Mitigation Strategies ◽  
Policy Implications ◽  
Transmission Model ◽  
Stochastic Dynamic ◽  
National Guidelines ◽  
Reproduction Ratio ◽  
Dynamic Transmission Model ◽  
Correctional Settings ◽  
The Impact

ABSTRACTObjectivesTo estimate the impact of various mitigation strategies on COVID-19 transmission in a U.S. jail beyond those offered in national guidelines.MethodsWe developed a stochastic dynamic transmission model of COVID-19 in one large urban U.S. jail among staff and incarcerated individuals. We divided the outbreak into four intervention phases: the start of the outbreak, depopulation of the jail, increased proportion of people in single cells, and asymptomatic testing. We used the next generation method to estimate the basic reproduction ratio, R0, in each phase. We estimated the fraction of new cases, hospitalizations, and deaths averted by these interventions along with the standard measures of sanitization, masking, and social distancing interventions.ResultsFor the first outbreak phase, the estimated R0 was 8.23 (95% CrI: 5.01-12.90), and for the subsequent phases, R0,phase 2 = 3.58 (95% CrI: 2.46-5.08), R0,phase 3 = 1.72 (95% CrI: 1.41-2.12), and R0,phase 4 = 0.45 (95% CrI: 0.32-0.59). In total, the jail’s interventions prevented approximately 83% of projected cases and hospitalizations and 89% of deaths over 83 days.ConclusionsDepopulation, single celling, and asymptomatic testing within jails can be effective strategies to mitigate COVID-19 transmission in addition to standard public health measures.Policy ImplicationsDecision-makers should prioritize reductions in the jail population, single celling, and testing asymptomatic populations, as additional measures to manage COVID-19 within correctional settings.

scholarly journals A novel COVID-19 epidemiological model with explicit susceptible and asymptomatic isolation compartments reveals unexpected consequences of timing social distancing

2020 ◽  
Author(s):  
Jana L. Gevertz ◽  
James M. Greene ◽  
Cynthia Sanchez-Tapia ◽  
Eduardo D. Sontag
Keyword(s):  
Disease Transmission ◽  
Control Strategies ◽  
Dynamical Behavior ◽  
Critical Time ◽  
Epidemiological Model ◽  
Appreciable Effect ◽  
Negative Effects ◽  
Social Distancing ◽  
The Impact ◽  
Implementation Delay

AbstractMotivated by the current COVID-19 epidemic, this work introduces an epidemiological model in which separate compartments are used for susceptible and asymptomatic “socially distant” populations. Distancing directives are represented by rates of flow into these compartments, as well as by a reduction in contacts that lessens disease transmission. The dynamical behavior of this system is analyzed, under various different rate control strategies, and the sensitivity of the basic reproduction number to various parameters is studied. One of the striking features of this model is the existence of a critical implementation delay (“CID”) in issuing separation mandates: while a delay of about two weeks does not have an appreciable effect on the peak number of infections, issuing mandates even slightly after this critical time results in a far greater incidence of infection. Thus, there is a nontrivial but tight “window of opportunity” for commencing social distancing in order to meet the capacity of healthcare resources. However, if one wants to also delay the timing of peak infections –so as to take advantage of potential new therapies and vaccines– action must be taken much faster than the CID. Different relaxation strategies are also simulated, with surprising results. Periodic relaxation policies suggest a schedule which may significantly inhibit peak infective load, but that this schedule is very sensitive to parameter values and the schedule’s frequency. Furthermore, we considered the impact of steadily reducing social distancing measures over time. We find that a too-sudden reopening of society may negate the progress achieved under initial distancing guidelines, but the negative effects can be mitigated if the relaxation strategy is carefully designed.

scholarly journals Effectiveness of interventions to reduce COVID-19 transmission in a large urban jail: a model-based analysis

BMJ Open ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. e042898
Author(s):  
Giovanni S P Malloy ◽  
Lisa Puglisi ◽  
Margaret L Brandeau ◽  
Tyler D Harvey ◽  
Emily A Wang
Keyword(s):  
Single Cells ◽  
Credible Interval ◽  
Mitigation Strategies ◽  
Transmission Model ◽  
Secondary Outcome ◽  
Stochastic Dynamic ◽  
National Guidelines ◽  
Reproduction Ratio ◽  
Dynamic Transmission Model ◽  
The Impact

ObjectivesWe aim to estimate the impact of various mitigation strategies on COVID-19 transmission in a US jail beyond those offered in national guidelines.DesignWe developed a stochastic dynamic transmission model of COVID-19.SettingOne anonymous large urban US jail.ParticipantsSeveral thousand staff and incarcerated individuals.InterventionsThere were four intervention phases during the outbreak: the start of the outbreak, depopulation of the jail, increased proportion of people in single cells and asymptomatic testing. These interventions were implemented incrementally and in concert with one another.Primary and secondary outcome measuresThe basic reproduction ratio, R0, in each phase, as estimated using the next generation method. The fraction of new cases, hospitalisations and deaths averted by these interventions (along with the standard measures of sanitisation, masking and social distancing interventions).ResultsFor the first outbreak phase, the estimated R0 was 8.44 (95% credible interval (CrI): 5.00 to 13.10), and for the subsequent phases, R0,phase 2=3.64 (95% CrI: 2.43 to 5.11), R0,phase 3=1.72 (95% CrI: 1.40 to 2.12) and R0,phase 4=0.58 (95% CrI: 0.43 to 0.75). In total, the jail’s interventions prevented approximately 83% of projected cases, hospitalisations and deaths over 83 days.ConclusionsDepopulation, single celling and asymptomatic testing within jails can be effective strategies to mitigate COVID-19 transmission in addition to standard public health measures. Decision makers should prioritise reductions in the jail population, single celling and testing asymptomatic populations as additional measures to manage COVID-19 within correctional settings.

scholarly journals Effectiveness of Second Wave COVID-19 Response Strategies in Australia

2020 ◽  
Author(s):  
George Milne ◽  
Simon Xie ◽  
Dana Poklepovich ◽  
Dan O’Halloran ◽  
Matthew Yap ◽  
...  
Keyword(s):  
Health Care Facilities ◽  
Mitigation Strategies ◽  
Transmission Model ◽  
Alternative Response ◽  
Social Distancing ◽  
Response Strategies ◽  
Department Of Health ◽  
Response Measures ◽  
The Impact ◽  
Second Wave

AbstractBackgroundThere is a significant challenge in responding to second waves of COVID-19 cases, with governments being hesitant in introducing hard lockdown measures given the resulting economic impact. In addition, rising case numbers reflect an increase in coronavirus transmission some time previously, so timing of response measures is highly important. Australia experienced a second wave from June 2020 onwards, confined to greater Melbourne, with initial social distancing measures failing to reduce rapidly increasing case numbers. We conducted a detailed analysis of this outbreak, together with an evaluation of the effectiveness of alternative response strategies, to provide guidance to countries experiencing second waves of SARS-Cov-2 transmission.MethodAn individual-based transmission model was used to 1) describe a second-wave COVID-19 epidemic in Australia; 2) evaluate the impact of lockdown strategies used; and 3) evaluate effectiveness of alternative mitigation strategies. The model was calibrated using daily diagnosed case data prior to lockdown. Specific social distancing interventions were modelled by adjusting person-to-person contacts in mixing locations.ResultsModelling earlier activation of lockdown measures are predicted to reduce total case numbers by more than 50%. Epidemic peaks and duration of the second wave were also shown to reduce. Our results suggest that activating lockdown measures when second-wave case numbers first indicated exponential growth, would have been highly effective in reducing COVID-19 cases. The model was shown to realistically predict the epidemic growth rate under the social distancing measures applied, validating the methods applied.ConclusionsThe timing of social distancing activation is shown to be critical to their effectiveness. Data showing exponential rise in cases, doubling every 7-10 days, can be used to trigger early lockdown measures. Such measures are shown to be necessary to reduce daily and total case numbers, and the consequential health burden, so preventing health care facilities being overwhelmed. Early control of second wave resurgence potentially permits strict lockdown measures to be eased earlier.All authors have seen and approved the manuscript. Research funding from Department of Health, Western Australia and Department of Health, Queensland is acknowledged. The authors confirm that these organisations had no influence on the submitted work, nor are there any competing interests.

scholarly journals A novel approach for evaluating contact patterns and risk mitigation strategies for COVID-19 in English Primary Schools with application of Structured Expert Judgement

2020 ◽  
Author(s):  
Stephen RJ Sparks ◽  
William P Aspinall ◽  
Ellen Brooks-Pollock ◽  
Leon Danon ◽  
Roger Cooke ◽  
...  
Keyword(s):  
Primary Schools ◽  
Risk Mitigation ◽  
Expert Elicitation ◽  
Mitigation Strategies ◽  
Teaching Staff ◽  
Older Children ◽  
Social Distancing ◽  
Contact Patterns ◽  
Risk Mitigation Strategies ◽  
The Impact

Background Contact patterns are the drivers of close-contacts infections, such as COVID-19. In an effort to control COVID-19 transmission in the UK, schools were closed on 23 March 2020. With social distancing in place, Primary Schools were partially re-opened on 1 June 2020, with plans to fully re-open in September 2020. The impact of social distancing and risk mitigation measures on childrens contact patterns is not known. Methods We conducted a structured expert elicitation of a sample of Primary Headteachers to quantify contact patterns within schools in pre-COVID-19 times and how these patterns were expected to change upon re-opening. Point estimates with uncertainty were determined by a formal performance-based algorithm. Additionally, we surveyed school Headteachers about risk mitigation strategies and their anticipated effectiveness. Results Expert elicitation provides estimates of contact patterns that are consistent with contact surveys. We report mean number of contacts per day for four cohorts within schools along with a range at 90% confidence for the variations of contacts among individuals. Prior to lockdown, we estimate that, mean numbers per day, younger children (Reception and Year 1) made 15 contacts [range 8..35] within school, older children (Year 6) 18 contacts [range 5..55], teaching staff 25 contacts [range 4..55) and non-classroom staff 11 contacts [range 2..27]. Compared to pre-COVID times, after schools re-opened the mean number of contacts were reduced by about 53% for young children, about 62% for older children, about 60% for classroom staff and about 64% for other staff. Contacts between teaching and non-teaching staff reduced by 80%, which is consistent with other independent estimates. The distributions of contacts per person are asymmetric indicating a heavy tail of individuals with high contact numbers. Conclusions We interpret the reduction in childrens contacts as a consequence of efforts to reduce mixing with interventions such as forming groups of children (bubbles) who are organized to learn together to limit contacts. Distributions of contacts for children and adults can be used to inform COVID-19 transmission modelling. Our findings suggest that while official DfE guidelines form the basis for risk mitigation in schools, individual schools have adopted their own bespoke strategies, often going beyond the guidelines.

scholarly journals Possible fates of the spread of SARS-CoV-2 in the Mexican context

2020 ◽  
Vol 7 (9) ◽  
pp. 200886
Author(s):  
I. Santamaría-Holek ◽  
V. Castaño
Keyword(s):  
Time Evolution ◽  
Compartmental Model ◽  
Time Dependent ◽  
Social Policies ◽  
Infection Rates ◽  
Conceptual Tool ◽  
Epidemiological Research ◽  
Social Distancing ◽  
The Impact

The determination of the adequate time for house confinement and when social distancing restrictions should end are now two of the main challenges that any country has to face in an ongoing battle against SARS-CoV-2. The possibility of a new outbreak of the pandemic and how to avoid it is, nowadays, one of the primary objectives of epidemiological research. In this work, we present an innovative compartmental model that explicitly introduces the number of active cases, and employ it as a conceptual tool to explore the possible fates of the spread of SARS-CoV-2 in the Mexican context. We incorporated the impact of starting, inattention and end of restrictive social policies on the pandemic’s time evolution via time-dependent corrections to the infection rates. The magnitude and impact on the epidemic due to post-social restrictive policies are also studied. The scenarios generated by the model could help authorities determine an adequate time and population load that may be allowed to reassume normal activities.

scholarly journals Modelling the impact of household size distribution on the transmission dynamics of COVID-19

2021 ◽  
Author(s):  
Pengyu Liu ◽  
Lisa McQuarrie ◽  
Yexuan Song ◽  
Caroline Colijn
Keyword(s):  
British Columbia ◽  
Size Distribution ◽  
Household Size ◽  
Epidemiological Model ◽  
Transmission Dynamics ◽  
Social Distancing ◽  
Household Transmission ◽  
The Impact ◽  
Pharmaceutical Interventions ◽  
At Home

AbstractUnder the implementation of non-pharmaceutical interventions such as social distancing and lockdowns, household transmission has been shown to be significant for COVID-19, posing challenges for reducing incidence in settings where people are asked to self-isolate at home and to spend increasing amounts of time at home due to distancing measures. Accordingly, characteristics of households in a region have been shown to relate to transmission heterogeneity of the virus. We introduce a stochastic epidemiological model to examine the impact of the household size distribution in a region on the transmission dynamics. We choose parameters to reflect incidence in two health regions of the Greater Vancouver area in British Columbia and simulate the impact of distancing measures on transmission, with household size distribution the only different parameter between simulations for the two regions. Our result suggests that the dissimilarity in household size distribution alone can cause significant differences in incidence of the two regions, and the distributions drive distinct dynamics that match reported cases. Furthermore, our model suggests that offering individuals a place to isolate outside their household can speed the decline in cases, and does so more effectively where there are more larger households.

Only vaccines or drugs will end social distancing

2020 ◽  
Keyword(s):  
International Travel ◽  
Mitigation Strategies ◽  
London School ◽  
Content Type ◽  
Social Distancing ◽  
Travel And Tourism ◽  
Travel Restrictions ◽  
The Unemployed ◽  
The Impact

Significance Studies currently estimate that only a small fraction of people were infected prior to strict social-distancing enforcement. A major second wave of COVID-19 cases and deaths is likely if countries exit lockdowns without strategies to reduce transmissibility of the virus. However, policymakers have few tried-and-tested strategies to fall upon as the situation is unprecedented. Researchers are now rushing to produce models to estimate the impact of epidemic mitigation strategies while they wait for more data. Impacts A new London School of Hygiene and Tropical Medicine platform, pooling worldwide interventions, could help clarify intervention effects. Long-term social distancing will particularly harm the wellbeing of the unemployed, self-employed and elderly in particular. Continued remote working or cyclical return to work will help moderate demand on healthcare capacity in the medium term. International travel restrictions will have a lasting impact on the travel and tourism sectors.

scholarly journals COVID-19, Face Masks, and Social Interaction: How a Global Pandemic Is Shining a Light on the Importance of Face-to-Face Communication

2021 ◽  
pp. 1-9
Author(s):  
Tina M. Grieco-Calub
Keyword(s):  
Speech Recognition ◽  
Cognitive Abilities ◽  
Mitigation Strategies ◽  
Visual Speech ◽  
Daily Lives ◽  
Social Distancing ◽  
Face To Face ◽  
Global Pandemic ◽  
Speech Cues ◽  
The Impact

Purpose The purpose of this article is to discuss the impact of COVID-19 mitigation strategies on face-to-face communication. The article covers three main areas: the effect of face masks and social distancing on aspects of communication, including speech production, speech recognition, and emotion recognition; the effect of face masks on access to visual speech cues; and downstream effects of poor speech recognition on language and cognitive abilities. Conclusions The use of face masks and social distancing are proven mitigation strategies to minimize the spread of COVID-19 and other airborne diseases. However, these strategies may place individuals with hearing, speech, and language disorders at greater risk for communication problems in their daily lives. Practitioners who work directly with these patients should consider these issues when discussing communication strategies with their patients.

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