scholarly journals Community Transmission via Indirect Media-To-Person Route: A Missing Link in the Rapid Spread of COVID-19

2021 ◽  
Vol 9 ◽  
Author(s):  
Qunfang Hu ◽  
Lei He ◽  
Ying Zhang

To prevent the spread of coronavirus disease 2019 (COVID-19), stringent quarantine measures have been implemented so that healthy people and virus carriers have isolated themselves in the same community owing to the limit capacity of healthcare facilities. With the exponential growth of the infected population, the residential environment is contaminated by fomites from the infected residents and consequently threating the health of susceptible residents. Till now, little has been acknowledged on this indirect transmission route and its role on community transmission. Here we address the impact of self-isolated virus carriers on the residential environment and elucidate the potential transmission pathways via contaminated environment in communities. We urge further investigation on the superspreading cases in communities and hope to arouse the attention to evaluate the potential risk of indirect transmission route as well as the corresponding control measures.

2020 ◽  
pp. 1-26
Author(s):  
MARGARET BROWN ◽  
MIKO JIANG ◽  
CHAYU YANG ◽  
JIN WANG

We present a new mathematical model to investigate the transmission dynamics of cholera under disease control measures that include education programs and water sanitation. The model incorporates the impact of education programs into the disease transmission rates and that of water sanitation into the environmental pathogen dynamics. We conduct a detailed analysis to the autonomous system of the model and establish the local and global stabilities of its equilibria that characterize the threshold dynamics of cholera. We then perform an optimal control study on the general model with time-dependent controls and explore effective approaches to implement the education programs and water sanitation while balancing their costs. Our analysis and simulation highlight the complex interaction among the direct and indirect transmission pathways of the disease, the intrinsic growth of the environmental pathogen and the impact of multiple control measures, and their roles in collectively shaping the transmission dynamics of cholera.


2021 ◽  
Vol 9 ◽  
Author(s):  
Valentina Costantino ◽  
Chandini Raina MacIntyre

Objective(s): To estimate the impact of universal community face mask use in Victoria, Australia along with other routine disease control measures in place.Methods: A mathematical modeling study using an age structured deterministic model for Victoria, was simulated for 123 days between 1 June 2020 and 1 October 2020, incorporating lockdown, contact tracing, and case findings with and without mask use in varied scenarios. The model tested the impact of differing scenarios of the universal use of face masks in Victoria, by timing, varying mask effectiveness, and uptake.Results: A six-week lockdown with standard control measures, but no masks, would have resulted in a large resurgence by September, following the lifting of restrictions. Mask use can substantially reduce the epidemic size, with a greater impact if at least 50% of people wear a mask which has an effectiveness of at least 40%. Early mask use averts more cases than mask usage that is only implemented closer to the peak. No mask use, with a 6-week lockdown, results in 67,636 cases and 120 deaths by 1 October 2020 if no further lockdowns are used. If mask use at 70% uptake commences on 23 July 2020, this is reduced to 7,961 cases and 42 deaths. We estimated community mask effectiveness to be 11%.Conclusion(s): Lockdown and standard control measures may not have controlled the epidemic in Victoria. Mask use can substantially improve epidemic control if its uptake is higher than 50% and if moderately effective masks are used. Early mask use should be considered in other states if community transmission is present, as this has a greater effect than later mask wearing mandates.


Author(s):  
Nick Scott ◽  
Anna Palmer ◽  
Dominic Delport ◽  
Romesh Abeysuriya ◽  
Robyn Stuart ◽  
...  

AbstractAimsWe assessed COVID-19 epidemic risks associated with relaxing a set of physical distancing restrictions in the state of Victoria, Australia – a setting with low community transmission – in line with a national framework that aims to balance sequential policy relaxations with longer-term public health and economic need.MethodsAn agent-based model, Covasim, was calibrated to the local COVID-19 epidemiological and policy environment. Contact networks were modelled to capture transmission risks in households, schools and workplaces, and a variety of community spaces (e.g. public transport, parks, bars, cafes/restaurants) and activities (e.g. community or professional sports, large events). Policy changes that could prevent or reduce transmission in specific locations (e.g. opening/closing businesses) were modelled in the context of interventions that included testing, contact tracing (including via a smartphone app), and quarantine.ResultsPolicy changes leading to the gathering of large, unstructured groups with unknown individuals (e.g. bars opening, increased public transport use) posed the greatest risk, while policy changes leading to smaller, structured gatherings with known individuals (e.g. small social gatherings) posed least risk. In the model, epidemic impact following some policy changes took more than two months to occur. Model outcomes support continuation of working from home policies to reduce public transport use, and risk mitigation strategies in the context of social venues opening, such as >30% population-uptake of a contact-tracing app, physical distancing policies within venues reducing transmissibility by >40%, or patron identification records being kept to enable >60% contact tracing.ConclusionsIn a low transmission setting, care should be taken to avoid lifting sequential COVID-19 policy restrictions within short time periods, as it could take more than two months to detect the consequences of any changes. These findings have implications for other settings with low community transmission where governments are beginning to lift restrictions.


Author(s):  
Ejaz Ahmad Khan ◽  
Maida Umar ◽  
Maryam Khalid

AbstractBackgroundRecent pandemic of the Noval Coronal Virus (COVID 19) has claimed more than 200,000 lives and about 3.8 million infected worldwide. Countries are being gradually exposed to its devastating threat without being properly prepared and with inadequate response. COVID 19’s first two cases were reported in Pakistan on February 26, 2020. We present a model depicting progression of epidemiology curve for Pakistan with and without interventions in view of its health system’ response capacity in near future.MethodologyWe used a modified compartmental epidemiological SEIR model to describe the outbreak of COVID-19 in Pakistan including the possibility of asymptomatic infection and presymptomatic transmission. The behavior of the dynamic model is determined by a set of clinical parameters and transmission rate.ResultsWe estimated that in the absence of a set of proven interventions, the total susceptible population would be 43.24 million, exposed individuals would be almost 32 million, asymptomatic cases would be 13.13 million, mildly infected 30.64 million, severely infected slightly more than 6 million and critical cases would be around 967,000 in number. By that time, almost 760,000 fatalities of infected critical would have taken place. Comparing with the healthcare capacity of Pakistan, if we could “flatten the curve” to a level below the dashed grey line, the healthcare system will be capable of managing the cases with ideal healthcare facilities, where the grey line representing the healthcare capacity of Pakistan. With the intervention in place, the number of symptomatic infected individuals is expected to be almost 20 million.ConclusionWe consider the impact of intervention and control measures on the spread of COVID-19 with 30% reduction in transmission from mild cases in case a set of interventions are judiciously in place to mitigate its impact.


2019 ◽  
Vol 221 (11) ◽  
pp. 1782-1794 ◽  
Author(s):  
Sarah M Bartsch ◽  
Kim F Wong ◽  
Owen J Stokes-Cawley ◽  
James A McKinnell ◽  
Chenghua Cao ◽  
...  

Abstract Background Clinical testing detects a fraction of carbapenem-resistant Enterobacteriaceae (CRE) carriers. Detecting a greater proportion could lead to increased use of infection prevention and control measures but requires resources. Therefore, it is important to understand the impact of detecting increasing proportions of CRE carriers. Methods We used our Regional Healthcare Ecosystem Analyst–generated agent-based model of adult inpatient healthcare facilities in Orange County, California, to explore the impact that detecting greater proportions of carriers has on the spread of CRE. Results Detecting and placing 1 in 9 carriers on contact precautions increased the prevalence of CRE from 0% to 8.0% countywide over 10 years. Increasing the proportion of detected carriers from 1 in 9 up to 1 in 5 yielded linear reductions in transmission; at proportions >1 in 5, reductions were greater than linear. Transmission reductions did not occur for 1, 4, or 5 years, varying by facility type. With a contact precautions effectiveness of ≤70%, the detection level yielding nonlinear reductions remained unchanged; with an effectiveness of >80%, detecting only 1 in 5 carriers garnered large reductions in the number of new CRE carriers. Trends held when CRE was already present in the region. Conclusion Although detection of all carriers provided the most benefits for preventing new CRE carriers, if this is not feasible, it may be worthwhile to aim for detecting >1 in 5 carriers.


2020 ◽  
Vol 15 ◽  
pp. 31 ◽  
Author(s):  
Anass Bouchnita ◽  
Aissam Jebrane

The coronavirus disease (COVID-19) pandemic emerged in Wuhan, China, in December 2019 and caused a serious threat to global public health. In Morocco, the first confirmed COVID-19 case was reported on March 2, 2020. Since then, several non-pharmaceutical interventions were used to slow down the spread of the disease. In this work, we use a previously developed multi-scale model of COVID-19 transmission dynamics to quantify the effects of restricting population movement and wearing face masks on disease spread in Morocco. In this model, individuals are represented as agents that move, become infected, transmit the disease, develop symptoms, go into quarantine, die by the disease, or become immunized. We describe the movement of agents using a social force model and we consider both modes of direct and indirect transmission. We use the model to simulate the impact of restricting the movement of the population movement and mandating the wearing of masks on the spread of COVID-19. The model predicts that adopting these two measures would reduce the total number of cases by 64%. Furthermore, the relative incidence of indirect transmission increases when control measures are adopted.


2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Alexander F. Siegenfeld ◽  
Yaneer Bar-Yam

Abstract While the spread of communicable diseases such as coronavirus disease 2019 (COVID-19) is often analyzed assuming a well-mixed population, more realistic models distinguish between transmission within and between geographic regions. A disease can be eliminated if the region-to-region reproductive number—i.e., the average number of other regions to which a single infected region will transmit the disease—is reduced to less than one. Here we show that this region-to-region reproductive number is proportional to the travel rate between regions and exponential in the length of the time-delay before region-level control measures are imposed. If, on average, infected regions (including those that become re-infected in the future) impose social distancing measures shortly after experiencing community transmission, the number of infected regions, and thus the number of regions in which such measures are required, will exponentially decrease over time. Elimination will in this case be a stable fixed point even after the social distancing measures have been lifted from most of the regions.


2021 ◽  
Vol 8 (2) ◽  
Author(s):  
Mahaad Issa Shammas

This study examines the invasiveness of Parthenium hysterophorus L. considered as harmful, unpleasant noxious invasive weed in Sultanate of Oman. Since the subject of investigation has allelopathic effects, the author’s objective is to identify its abundance, its impact to environment, human and animal health. Allelopathy of this invasive weed has started to be known and considered by the farmers and harvesters. The harmful and socio-economic effects of the weed to humans, animals and to landscape are not fully known nor understood by the local farmers and pastoralists in the southern part of Oman where this weed is most invasive. Data were collected through field observation, informal interviews, focus group discussions and survey questionnaire. They were treated and analysed using descriptive statistics. Findings prompted the participants to propose possible and practical control solutions for the spread of P. hysterophorus if not totally eradicated, considering the availability of resources, level of awareness and the socio-economic status of the affected regions. The results of the investigation are hoped to improve the over-all management that are being conducted by the concerned agencies and volunteers towards the rapid spread of the weed. The findings revealed that P. hysterophorus has serious impacts on vegetation, pastures and agriculture, as it was observed in reduced level growth of both plants and trees. The possible control measures gathered from the participants indicate that they are willing to cooperate and learn more about the impact of the weed.


Author(s):  
Clement Kevin Edet ◽  
Anthony Ike Wegbom ◽  
Victor Alangibi Kiri

Abstract Introduction: The outbreak of coronavirus (COVID-19) has impacted the lifestyles of people all over the globe as well as the economies of virtually every country. Several control measures have been introduced by both the State and Federal governments to fight the disease since its outbreak in Nigeria. In spite of all the measures, the disease is still ravaging the country. Therefore, this study investigated the knowledge, attitudes, and practices (KAP) of the clients who attended public primary healthcare facilities (PHFs) in Rivers State, Nigeria about COVID-19.Methods: A cross-sectional study was conducted involving the clients seeking care at the 92 PHFs across the 23 Local Government Areas (LGAs) of Rivers State, Nigeria. The respondents were selected using simple random sampling and data were analysed using mean and standard deviation, percentages, chi-square test and binary logistic regression. Results: A total of 434 respondents voluntarily participated in the study out of 460 questionnaires that were distributed, indicating a high response rate of 94.3%. The proportions of respondents with scores moderate and above in KAP were 86.6% (62.9+23.7), 80.6% (57.6+23.0), and 58.0% (30.8+27.2) respectively. Occupation, educational level, and senatorial district of respondents were significantly associated with knowledge and attitude (P<0.05). Preventive practice against COVID-19 was influenced by age and senatorial district among patients attending primary health facilities (P<0.05). Also, the knowledge level was significantly associated with both attitude and COVID-19 related practices (P=0.000). The multiple logistic regression results revealed some demographics with significant association with KAP. Respondents who have sufficient knowledge about COVID-19 were significantly less likely to have a negative attitude and to adopt poor COVID-19 related practices than those that had insufficient knowledge.Conclusion: Based on the findings of this study, we suggest public health education programs on COVID-19 should principally be targeted at individuals with low knowledge level, lower educational attainment, and those residing in the Rivers South-East senatorial zone. Such efforts may mitigate the impact of COVID-19 on the target population in Rivers State.


2020 ◽  
Author(s):  
Thu-Anh Nguyen ◽  
Quoc Nguyen Cuong ◽  
Anh Le Thi Kim ◽  
Huyen Nguyen Nguyen ◽  
Thao Nguyen Thi Huong

AbstractObjectivesHealth care system of many countries are facing a surging burden of COVID-19. Although Vietnam has successfully controlled the COVID-19 pandemic to date, there is a sign of initial community transmission. An estimate of possible scenarios to prepare health resources in the future is needed. We used modelling methods to estimate impacts of mitigation measures on the COVID-19 pandemic in Vietnam.MethodsSEIR model built in the COVIDSIM1.1 tool was adopted using available data for estimation. The herd immunization scenario was with no intervention implemented. Other scenarios consisted of isolation and social distancing at different levels (25%, 50%, 75% and 10%, 20%, 30%, respectively). Outcomes include epidemic apex, daily new and cumulative cases, deaths, hospitalized patients and ICU beds needed.ResultsBy April 8, 2020, there would be 465 infected cases with COVID-19 in Viet Nam, of those 50% were detected. Cumulatively, there would be 1,400 cases and 30 deaths by end of 2020, if 75% of cases was detected and isolated, and 30% of social distancing could be maintained.The most effective intervention scenario is the detection and isolation of 75% infected cases and reduction of 10% social contacts. This will require an expansion of testing capacity at health facilities and in the community, posing a challenge to identify high-risk groups to prioritized testing.ConclusionsIn a localized epidemic setting, the expansion of testing should be the key measure to control the epidemic. Social distancing plays a significant role to prevent further transmission to the community.


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