Assessment of Social Distancing for Controlling COVID-19 in Korea: An Age-Structured Modeling Approach

The outbreak of the novel coronavirus disease 2019 (COVID-19) occurred all over the world between 2019 and 2020. The first case of COVID-19 was reported in December 2019 in Wuhan, China. Since then, there have been more than 21 million incidences and 761 thousand casualties worldwide as of 16 August 2020. One of the epidemiological characteristics of COVID-19 is that its symptoms and fatality rates vary with the ages of the infected individuals. This study aims at assessing the impact of social distancing on the reduction of COVID-19 infected cases by constructing a mathematical model and using epidemiological data of incidences in Korea. We developed an age-structured mathematical model for describing the age-dependent dynamics of the spread of COVID-19 in Korea. We estimated the model parameters and computed the reproduction number using the actual epidemiological data reported from 1 February to 15 June 2020. We then divided the data into seven distinct periods depending on the intensity of social distancing implemented by the Korean government. By using a contact matrix to describe the contact patterns between ages, we investigated the potential effect of social distancing under various scenarios. We discovered that when the intensity of social distancing is reduced, the number of COVID-19 cases increases; the number of incidences among the age groups of people 60 and above increases significantly more than that of the age groups below the age of 60. This significant increase among the elderly groups poses a severe threat to public health because the incidence of severe cases and fatality rates of the elderly group are much higher than those of the younger groups. Therefore, it is necessary to maintain strict social distancing rules to reduce infected cases.

Download Full-text

Age-Structured Model for COVID-19: Effectiveness of Social Distancing and Contact Reduction

10.21203/rs.3.rs-33480/v1 ◽

2020 ◽

Author(s):

Mark Kimathi ◽

Samuel Mwalili ◽

Viona Ojiambo ◽

Duncan Gathungu

Keyword(s):

Deterministic Model ◽

Age Groups ◽

School Closure ◽

Model Parameters ◽

Suitable Model ◽

Age Group ◽

Social Distancing ◽

First Case ◽

Age Structured ◽

The Impact

Abstract Background: Coronavirus disease 2019 is caused by severe acute respiratory syndrome coronavirus 2. The disease has spread to almost every country in the world. Kenya reported its first case on 13th of March 2020. From 16th March 2020, the country instituted various social distancing strategies to reduce the transmission and flatten the epidemic curve. These strategies include school closure, dusk-to-dawn curfew, and travel restriction across counties, especially Nairobi, Mombasa and Kwale. An age-structured compartmental model was developed to assess the impact of non-pharmaceutical interventions on severity of infections, hospital demands and deaths. Methods: The population is divided into four age-groups and for each age-group there are seven compartments, namely: susceptible , exposed, asymptomatic, mild, severe, critical, death and recovered. The contact matrices between the different ages are integrated into an age-structured deterministic model via the force of infection. This model is represented by ordinary differential equations and solved using Runge–Kutta methods, with suitable model parameters. Simulation results for the unmitigated and mitigated scenarios were depicted, for the different age-groups. Results: The 45% reduction in contacts for 60-days period resulted to between 11.5-13% reduction of infections severity and deaths, while for the 190-days period yielded between 18.8-22.7% reduction. The peak of infections in the 60-days mitigation was higher and happened about 2 months after the relaxation of mitigation as compared to that of the 190-days mitigation, which happened just a month after mitigation were relaxed. Low numbers of cases in children under 15 years was attributed to low susceptibility of persons in this age-group. High numbers of cases are reported in the 15-29 years and 30-59 years age bands since these individuals have wider interaction spheres, and they form a significant percentage of Kenya population. Conclusion: Two mitigation periods, considered in the study, resulted to reductions in severe and critical cases, attack rates, hospital and ICU bed demands, as well as deaths, with the 190-days period giving higher reductions. The study revealed the age-dependency of the key health outputs.

Download Full-text

Vaccination Prioritization Strategies for COVID-19 in Korea: A Mathematical Modeling Approach

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18084240 ◽

2021 ◽

Vol 18 (8) ◽

pp. 4240

Author(s):

Yongin Choi ◽

James Slghee Kim ◽

Jung Eun Kim ◽

Heejin Choi ◽

Chang Hyeong Lee

Keyword(s):

Age Groups ◽

Epidemiological Data ◽

The Elderly ◽

Age Group ◽

Elderly Age ◽

Social Distancing ◽

Vaccination Strategies ◽

Effective Age ◽

Incidence And Mortality ◽

Age Dependent

Coronavirus disease 2019 (COVID-19) vaccination has recently started worldwide. As the vaccine supply will be limited for a considerable period of time in many countries, it is important to devise the effective vaccination strategies that reduce the number of deaths and incidence of infection. One of the characteristics of COVID-19 is that the symptom, severity, and mortality of the disease differ by age. Thus, when the vaccination supply is limited, age-dependent vaccination priority strategy should be implemented to minimize the incidences and mortalities. In this study, we developed an age-structured model for describing the transmission dynamics of COVID-19, including vaccination. Using the model and actual epidemiological data in Korea, we estimated the infection probability for each age group under different levels of social distancing implemented in Korea and investigated the effective age-dependent vaccination strategies to reduce the confirmed cases and fatalities of COVID-19. We found that, in a lower level of social distancing, vaccination priority for the age groups with the highest transmission rates will reduce the incidence mostly, but, in higher levels of social distancing, prioritizing vaccination for the elderly age group reduces the infection incidences more effectively. To reduce mortalities, vaccination priority for the elderly age group is the best strategy in all scenarios of levels of social distancing. Furthermore, we investigated the effect of vaccine supply and efficacy on the reduction in incidence and mortality.

Download Full-text

COVID-19 scenarios for comparing the effectiveness of age-specific vaccination regimes, exemplified for the city of Aschaffenburg (Germany)

10.1101/2021.08.31.21262915 ◽

2021 ◽

Author(s):

Tobias Krebs ◽

Holger von Jouanne-Diedrich ◽

Michael J Moeckel

Keyword(s):

Local Population ◽

Age Groups ◽

The Elderly ◽

Strong Increase ◽

Published Data ◽

Model Parameters ◽

Agent Based ◽

The Past ◽

The Impact ◽

The City

Purpose of this report: The purpose of this rapid communication is to illustrate the effectiveness of different vaccination regimes for controlling the number of severe and critical COVID-19 cases in the city of Aschaffenburg, Germany. Our results show that, despite numerous vaccinations in the past, further vaccinations are necessary to immunize the population and to keep the number of severe and critical cases low in the coming months. Considering that not all people can or want to receive vaccination, we compare different age-specific vaccination approaches. Applied Methods: We use the agent-based epidemiological simulator Covasim for discussing the impact of different vaccination strategies. We calibrate it to reproduce the historical course of the COVID-19 pandemic in the city of Aschaffenburg, Germany; for this, we model and integrate numerous public health interventions imposed on the local population. As for some of the political actions rigorous quantification is currently not available, we fit those unknown (free) model parameters to published data on the measured epidemiological dynamics. Then we calculate the state of immunization of the population, gained through infections and vaccinations, at any time in the past, including models for time-dependent immunity decay that have been made available in Covasim. Finally, we define and compare scenar-ios of different vaccination regimes, especially with regard to vaccinating adolescents and providing booster vaccinations to the elderly. Key message: Without further vaccinations, we expect a strong increase in severe and critical cases. In order to restrict their growth our simulations suggest that in all considered cases vaccinations of unvaccinated people is more effective than booster vaccinations for already fully vaccinated people. This applies even to vaccinations of young people who are not themselves at high risk of developing severe or critical illness. We attribute this observation to the fact that immunization of adolescents indirectly protects vulnerable age groups by preventing the spread of the virus more ef-fectively than further immunizing other age groups. This indicates that with the pandemic ongoing, strategies focussed on minimizing individual health risks by vaccinations may no longer coincide with those needed to minimize the num-ber of severe and critical cases.

Download Full-text

Evaluating the impact of two training interventions to improve diagnosis and case-management of malaria and pneumonia in Uganda

Epidemiology and Infection ◽

10.1017/s0950268816002107 ◽

2016 ◽

Vol 145 (1) ◽

pp. 194-207

Author(s):

D. M. SSEBULIBA ◽

R. OUIFKI ◽

C. PRETORIUS ◽

S. M. BURNETT ◽

M. K. MBONYE ◽

...

Keyword(s):

Mathematical Model ◽

Case Management ◽

Support Services ◽

Integrated Management ◽

Age Groups ◽

Malaria Prevalence ◽

Age Group ◽

Training Interventions ◽

Age Structured ◽

The Impact

SUMMARYWe present an age-structured mathematical model of malaria and pneumonia to study the effect of two capacity-building interventions: Integrated Management of Infectious Diseases (IMID) and On-site Support Services (OSS). IMID leads to a reduction in malaria prevalence by more than 2·4% across the [0,5), [5,14) and [14,50) age groups. IMID + OSS reduces it by more than 16·0% across all age groups. IMID decreases pneumonia prevalence by more than 3·0% across all age groups while IMID + OSS decreases it by more than 1·0% across all age groups. The number of malaria and pneumonia deaths is reduced by 7·8% by IMID across all age groups and IMID + OSS decreases this number by 30·5% across all age groups, which translates to saving a life of a child per month. Prevalence of malaria-pneumonia for the [0,5) age group is 0·52% at baseline, and IMID and IMID + OSS reduce it by 6·6% and 23·6%, respectively. There is no change in incidence of malaria or pneumonia disease episodes. The results also indicate that triaging of children contributes more than 50% to the effect of the interventions in reduction of deaths and a range of 14–91% in reduction of disease cases.

Download Full-text

Age-Specific Mathematical Model for Tuberculosis Transmission Dynamics in South Korea

Mathematics ◽

10.3390/math9080804 ◽

2021 ◽

Vol 9 (8) ◽

pp. 804

Author(s):

Sunmi Lee ◽

Hae-Young Park ◽

Hohyung Ryu ◽

Jin-Won Kwon

Keyword(s):

Mathematical Model ◽

Age Groups ◽

The Elderly ◽

Specific Model ◽

Transmission Dynamics ◽

Sensitivity Analyses ◽

Model Parameters ◽

Tuberculosis Transmission ◽

Latent Tb ◽

Public Private Mix

Korea has the highest burden of tuberculosis (TB) among Organization for Economic Co-operation and Development countries. Various strategies have been implemented to eradicate TB in Korea, and it is critical to evaluate previous TB management outcomes before framing future TB policies. Over the past few decades, the rapid increase in the aging population in Korea has substantially impacted the incidence of TB among the elderly. Thus, in this study, we aimed to develop a mathematical model for the assessment of TB management outcomes incorporating special features of TB transmission dynamics in Korea. First, we incorporate 2-age groups in our TB model because TB epidemics in Korea are different between the elderly and the non-elderly (<65 years vs. ≥65 years). Second, because the public-private mix has had a full-fledged impact since 2012, this study was divided into two periods (2001–2011 and 2012–2018). We developed a mathematical model of TB transmission dynamics with 2-age groups and age-specific model parameters were estimated based on actual TB epidemic data from 2001 to 2018. These parameters included transmission rates, relapse rates, and recovery rates. We conducted sensitivity analyses of various parameters, and investigated the impacts of these parameters on TB incidence. Our results demonstrate that the overall outcomes of both age-groups improved in the period of 2012–2018 compared with that in the period of 2001–2011. Age-specific interventions should be implemented to reduce the overall TB incidence. More intensive treatment efforts should be focused on the elderly, while the early detection and treatment rates for latent TB were the most significant factor to reduce TB incidence in both groups.

Download Full-text

Quantifying the impact of air pollution on the urban population of Brazil

Cadernos de Saúde Pública ◽

10.1590/s0102-311x2007001600013 ◽

2007 ◽

Vol 23 (suppl 4) ◽

pp. S529-S536 ◽

Cited By ~ 15

Author(s):

Izabel Marcilio ◽

Nelson Gouveia

Keyword(s):

Air Pollution ◽

Urban Population ◽

Hospital Admissions ◽

Age Groups ◽

The Elderly ◽

Impact Factors ◽

Pollution Levels ◽

Time Series Studies ◽

The Impact ◽

Respiratory Causes

This study aimed to quantify air pollution impact on morbidity and mortality in the Brazilian urban population using locally generated impact factors. Concentration-response coefficients were used to estimate the number of hospitalizations and deaths attributable to air pollution in seven Brazilian cities. Poisson regression coefficients (beta) were obtained from time-series studies conducted in Brazil. The study included individuals 65 years old and over and children under five. More than 600 deaths a year from respiratory causes in the elderly and 47 in children were attributable to mean air pollution levels, corresponding to 4.9% and 5.5% of all deaths from respiratory causes in these age groups. More than 4,000 hospital admissions for respiratory conditions were also attributable to air pollution. These results quantitatively demonstrate the currently observed contribution of air pollution to mortality and hospitalizations in Brazilian cities. Such assessment is thought to help support the planning of surveillance and control activities for air pollution in these and similar areas.

Download Full-text

Immediate Outcomes of Traumatic Brain Injury at a Tertiary Care Hospital Of Pakistan- A Retrospective Study

10.21203/rs.3.rs-84330/v1 ◽

2020 ◽

Author(s):

Maria Khan ◽

Uzair Yaqoob ◽

Zair Hassan ◽

Muhammad Muizz Uddin

Keyword(s):

Traumatic Brain Injury ◽

Retrospective Study ◽

Brain Injury ◽

Tertiary Care ◽

Epidemiological Data ◽

Initial Assessment ◽

Care Hospital ◽

Hospital Data ◽

Epidemiological Characteristics ◽

The Impact

Abstract Background: Traumatic Brain Injury (TBI) which is the leading cause of morbidity and mortality all over the world and the impact is much worse in Pakistan. The objective of the study is to describe the epidemiological characteristics of patients with TBI in our country and to determine the immediate outcomes of patients with TBI after the presentation.Method: This retrospective study was conducted at the Lady Reading Hospital. Data were extracted from the medical record room from January 1st to December 31st, 2019. The severity of TBI was based on Glasgow Coma Scale (GCS) and was divided into mild (GCS 13-15), moderate (GCS 9-12), and severe TBI (GCS <8) based on the GCS. SPSS v.23 was used for data analysis. Results: Out of 5047 patients, 3689 (73.1%) males and 1358 (26.9%) females. The most commonly affected age group was 0-10 years (25.6%) and 21-30 years (20.1%). was the predominant cause of injury (38.8%, n=1960) followed by fall (32.7%, n=1649). Most (93.6%, n=4710) of the TBIs were mild. After the full initial assessment and workup, and completing all first-aid management, the immediate outcome was divided into four, most frequent (67.2%, n=3393) of which was “disposed (discharged)”, and 9.3% (n=470) were admitted for further management.Conclusion: Our study represents a relatively conclusive picture of epidemiological data on the burden of TBI in Pakistan. Although a large proportion of patients had a mild TBI, they may likely be under-diagnosed. This warrants for further investigation of MTBI in population-based studies across the globe.

Download Full-text

High incidence of asymptomatic SARS-CoV-2 infection, Chongqing, China

10.1101/2020.03.16.20037259 ◽

2020 ◽

Cited By ~ 4

Author(s):

Yang Tao ◽

Panke Cheng ◽

Wen Chen ◽

Peng Wan ◽

Yaokai Chen ◽

...

Keyword(s):

Asymptomatic Patient ◽

Medical Center ◽

Age Groups ◽

The Elderly ◽

Hospital Length ◽

Hospital Length Of Stay ◽

Asymptomatic Patients ◽

Imported Cases ◽

History Of ◽

Epidemiological Characteristics

SummaryBackgroundSARS-CoV-2 has been a global pandemic, but the emergence of asymptomatic patients has caused difficulties in the prevention of the epidemic. Therefore, it is significant to understand the epidemiological characteristics of asymptomatic patients with SARS-CoV-2 infection.MethodsIn this single-center, retrospective and observational study, we collected data from 167 patients with SARS-CoV-2 infection treated in Chongqing Public Health Medical Center (Chongqing, China) from January to March 2020. The epidemiological characteristics and variable of these patients were collected and analyzed.Findings82.04% of the SARS-CoV-2 infected patients had a travel history in Wuhan or a history of contact with returnees from Wuhan, showing typical characteristics of imported cases, and the proportion of severe Covid-19 patients was 13.2%, of which 59% were imported from Wuhan. For the patients who was returnees from Wuhan, 18.1% was asymptomatic patients. In different infection periods, compared with the proportion after 1/31/2020, the proportion of asymptomatic patient among SARS-CoV-2 infected patient was higher(19% VS 1.5%). In different age groups, the proportion of asymptomatic patient was the highest(28.6%) in children group under 14, next in elder group over 70 (27.3%). Compared with mild and common Covid-19 patients, the mean latency of asymptomatic was longer (11.25 days VS 8.86 days), but the hospital length of stay was shorter (14.3 days VS 16.96 days).ConclusionThe SARS-CoV-2 prevention needs to focus on the screening of asymptomatic patients in the community with a history of contact with the imported population, especially for children and the elderly population.

Download Full-text

Excess mortality in Guadeloupe and Martinique, islands of the French West Indies, during the chikungunya epidemic of 2014

Epidemiology and Infection ◽

10.1017/s0950268818002315 ◽

2018 ◽

Vol 146 (16) ◽

pp. 2059-2065 ◽

Cited By ~ 10

Author(s):

A. R. R. Freitas ◽

P. M. Alarcón-Elbal ◽

M. R. Donalisio

Keyword(s):

Strong Correlation ◽

Excess Mortality ◽

Pearson Correlation ◽

Age Groups ◽

Epidemiological Data ◽

Mortality Data ◽

Surveillance Systems ◽

Mortality And Morbidity ◽

The Impact ◽

Excess Deaths

AbstractIn some chikungunya epidemics, deaths are not completely captured by traditional surveillance systems, which record case and death reports. We evaluated excess deaths associated with the 2014 chikungunya virus (CHIKV) epidemic in Guadeloupe and Martinique, Antilles. Population (784 097 inhabitants) and mortality data, estimated by sex and age, were accessed from the Institut National de la Statistique et des Études Économiques in France. Epidemiological data, cases, hospitalisations and deaths on CHIKV were obtained from the official epidemiological reports of the Cellule de Institut de Veille Sanitaire in France. Excess deaths were calculated as the difference between the expected and observed deaths for all age groups for each month in 2014 and 2015, considering the upper limit of 99% confidence interval. The Pearson correlation coefficient showed a strong correlation between monthly excess deaths and reported cases of chikungunya (R= 0.81,p< 0.005) and with a 1-month lag (R= 0.87,p< 0.001); and a strong correlation was also observed between monthly rates of hospitalisation for CHIKV and excess deaths with a delay of 1 month (R= 0.87,p< 0.0005). The peak of the epidemic occurred in the month with the highest mortality, returning to normal soon after the end of the CHIKV epidemic. There were excess deaths in almost all age groups, and excess mortality rate was higher among the elderly but was similar between male and female individuals. The overall mortality estimated in the current study (639 deaths) was about four times greater than that obtained through death declarations (160 deaths). Although the aetiological diagnosis of all deaths associated with CHIKV infection is not always possible, already well-known statistical tools can contribute to the evaluation of the impact of CHIKV on mortality and morbidity in the different age groups.

Download Full-text

The Impact of Cold and Heat on Years of Life Lost in a Northwestern Chinese City with Temperate Continental Climate

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph16193529 ◽

2019 ◽

Vol 16 (19) ◽

pp. 3529 ◽

Cited By ~ 2

Author(s):

Jiangtao Liu ◽

Yueling Ma ◽

Yuhong Wang ◽

Sheng Li ◽

Shuyu Liu ◽

...

Keyword(s):

Respiratory Diseases ◽

Heat Waves ◽

Age Groups ◽

The Elderly ◽

Years Of Life Lost ◽

Weather Variables ◽

Distributed Lag ◽

Heat Effects ◽

The Impact ◽

Continental Climate

Cold spells and heat waves in a changing climate are well known as great public-health concerns due to their adverse effects on human health. However, very few studies have quantified health impacts of heat and cold in the region of Northwestern China. The purpose of the present study was to evaluate the effects of cold and heat on years of life lost (YLL) in Lanzhou, a city with temperate continental climate. We compiled a daily dataset including deaths, weather variables, and air pollutants in Lanzhou, China, from 2014–2017. We used a distributed lag non-linear model to estimate single-day and cumulative effects of heat and cold on daily YLL. Results indicated that both cold and heat were associated with increased YLL for registered residents in Lanzhou. Estimated heat effects appeared immediately in the first two days, while estimated cold effects lasted over a longer period (up to 30 days). Cold significantly increased the YLL of all residents except for males and those with respiratory diseases (≥65 years). Our results showed that both heat and cold had more pronounced effects on cardiovascular diseases compared to respiratory diseases. Males might be more vulnerable to heat, while females might suffer more YLL from cold. The effects of cold or heat on the elderly might appear earlier and last longer than those for other age groups.

Download Full-text