Reducing travel-related SARS-CoV-2 transmission with layered mitigation measures: symptom monitoring, quarantine, and testing

Abstract Background Balancing the control of SARS-CoV-2 transmission with the resumption of travel is a global priority. Current recommendations include mitigation measures before, during, and after travel. Pre- and post-travel strategies including symptom monitoring, antigen or nucleic acid amplification testing, and quarantine can be combined in multiple ways considering different trade-offs in feasibility, adherence, effectiveness, cost, and adverse consequences. Methods We used a mathematical model to analyze the expected effectiveness of symptom monitoring, testing, and quarantine under different estimates of the infectious period, test-positivity relative to time of infection, and test sensitivity to reduce the risk of transmission from infected travelers during and after travel. Results If infection occurs 0–7 days prior to travel, immediate isolation following symptom onset prior to or during travel reduces risk of transmission while traveling by 30–35%. Pre-departure testing can further reduce risk, with testing closer to the time of travel being optimal even if test sensitivity is lower than an earlier test. For example, testing on the day of departure can reduce risk while traveling by 44–72%. For transmission risk after travel with infection time up to 7 days prior to arrival at the destination, isolation based on symptom monitoring reduced introduction risk at the destination by 42–56%. A 14-day quarantine after arrival, without symptom monitoring or testing, can reduce post-travel risk by 96–100% on its own. However, a shorter quarantine of 7 days combined with symptom monitoring and a test on day 5–6 after arrival is also effective (97--100%) at reducing introduction risk and is less burdensome, which may improve adherence. Conclusions Quarantine is an effective measure to reduce SARS-CoV-2 transmission risk from travelers and can be enhanced by the addition of symptom monitoring and testing. Optimal test timing depends on the effectiveness of quarantine: with low adherence or no quarantine, optimal test timing is close to the time of arrival; with effective quarantine, testing a few days later optimizes sensitivity to detect those infected immediately before or while traveling. These measures can complement recommendations such as social distancing, using masks, and hand hygiene, to further reduce risk during and after travel.

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Reducing travel-related SARS-CoV-2 transmission with layered mitigation measures: Symptom monitoring, quarantine, and testing

10.1101/2020.11.23.20237412 ◽

2020 ◽

Author(s):

Michael A. Johansson ◽

Hannah Wolford ◽

Prabasaj Paul ◽

Pamela S. Diaz ◽

Tai-Ho Chen ◽

...

Keyword(s):

Transmission Risk ◽

Mitigation Measures ◽

Infectious Period ◽

Time Of Arrival ◽

Optimal Test ◽

Symptom Monitoring ◽

Trade Offs ◽

Global Priority ◽

Time Of Infection ◽

Reduce Risk

AbstractBalancing the control of SARS-CoV-2 transmission with the resumption of travel is a global priority. Current recommendations include mitigation measures before, during, and after travel. Pre- and post-travel strategies including symptom monitoring, testing, and quarantine can be combined in multiple ways considering different trade-offs in feasibility, adherence, effectiveness, cost and adverse consequences. Here we use a mathematical model to analyze the expected effectiveness of symptom monitoring, testing, and quarantine under different estimates of the infectious period, test-positivity relative to time of infection, and test sensitivity to reduce the risk of transmission from infected travelers during and after travel. If infection occurs 0-7 days prior to travel, immediate isolation following symptom onset prior to or during travel reduces risk of transmission while traveling by 26-30%. Pre-departure testing can further reduce risk if testing is close to the time of departure. For example, testing on the day of departure can reduce risk while traveling by 37-61%. For transmission risk after travel with infection time up to 7 days prior to arrival at the destination, isolation based on symptom monitoring reduced introduction risk at the destination by 42-56%. A 14-day quarantine after arrival, without symptom monitoring or testing, can reduce risk by 97-100% on its own. However, a shorter quarantine of 7 days combined with symptom monitoring and a test on day 3-4 after arrival is also effective (95-99%) at reducing introduction risk and is less burdensome, which may improve adherence. To reduce the risk of introduction without quarantine, optimal test timing after arrival is close to the time of arrival; with effective quarantine after arrival, testing a few days later optimizes sensitivity to detect those infected immediately before or while traveling. These measures can complement recommendations such as social distancing, using masks, and hand hygiene, to further reduce risk during and after travel.

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Marginal Abatement Cost Curves for Water Scarcity Mitigation under Uncertainty

Water Resources Management ◽

10.1007/s11269-019-02376-8 ◽

2019 ◽

Vol 33 (12) ◽

pp. 4335-4349 ◽

Cited By ~ 2

Author(s):

Karin Sjöstrand ◽

Andreas Lindhe ◽

Tore Söderqvist ◽

Peter Dahlqvist ◽

Lars Rosén

Keyword(s):

Water Scarcity ◽

Abatement Cost ◽

Hot Water ◽

Marginal Abatement Cost ◽

Mitigation Measures ◽

Cost Curve ◽

Effective Measure ◽

Trade Offs ◽

Cost Curves ◽

The Impact

Abstract As water scarcity and drought become more common, planning to avoid their consequences becomes crucial. Measures to prevent the impact of new climate conditions are expected to be extensive, costly and associated with major uncertainties. It is therefore necessary that policymakers and practitioners in both the public and private sector can compare possible mitigation measures in order to make economically rational investment decisions. For this to be successful, decision-makers need relevant decision support. This paper presents a novel approach of constructing marginal abatement cost curves for comparing water scarcity mitigation measures while taking the underlying uncertainties into account. Uncertainties in input variables are represented by probability distributions and calculations are performed using Monte Carlo simulations. This approach is applied on the island of Gotland, one of the most water-stressed parts of Sweden, to provide the first marginal abatement cost curve in Europe for water scarcity mitigation in which municipal, agricultural, industrial and household measures are compared. The results show that the agricultural measure of on-farm storage has the greatest potential to increase water availability on the island. Among municipal measures, increased groundwater extraction and desalination offer the greatest potential, although desalination is almost 25 times more costly per cubic meter. The most cost-effective measure is linked to hot water savings in the hotel industry. The approach presented provides a quantitative visualization of the financial trade-offs and uncertainties implied by different mitigation measures. It provides critical economic insights for all parties concerned and is thus an important basis for decision-making.

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Robust estimation of SARS-CoV-2 epidemic in US counties

Scientific Reports ◽

10.1038/s41598-021-90195-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Hanmo Li ◽

Mengyang Gu

Keyword(s):

Transmission Rate ◽

Public Awareness ◽

Mitigation Measures ◽

Infectious Period ◽

Protective Measures ◽

Social Distancing ◽

The Public ◽

The Us ◽

Local Officials ◽

Us Counties

AbstractThe COVID-19 outbreak is asynchronous in US counties. Mitigating the COVID-19 transmission requires not only the state and federal level order of protective measures such as social distancing and testing, but also public awareness of time-dependent risk and reactions at county and community levels. We propose a robust approach to estimate the heterogeneous progression of SARS-CoV-2 at all US counties having no less than 2 COVID-19 associated deaths, and we use the daily probability of contracting (PoC) SARS-CoV-2 for a susceptible individual to quantify the risk of SARS-CoV-2 transmission in a community. We found that shortening by $$5\%$$ 5 % of the infectious period of SARS-CoV-2 can reduce around $$39\%$$ 39 % (or 78 K, $$95\%$$ 95 % CI: [66 K , 89 K ]) of the COVID-19 associated deaths in the US as of 20 September 2020. Our findings also indicate that reducing infection and deaths by a shortened infectious period is more pronounced for areas with the effective reproduction number close to 1, suggesting that testing should be used along with other mitigation measures, such as social distancing and facial mask-wearing, to reduce the transmission rate. Our deliverable includes a dynamic county-level map for local officials to determine optimal policy responses and for the public to better understand the risk of contracting SARS-CoV-2 on each day.

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COVID-19 Community Transmission among Healthcare Workers at a Tertiary Care Cardiac Center

Medical Sciences ◽

10.3390/medsci9030049 ◽

2021 ◽

Vol 9 (3) ◽

pp. 49

Author(s):

Mazin Barry ◽

Asirvatham Alwin Robert ◽

Mohamad-Hani Temsah ◽

Syed Abdul Bari ◽

Muhammad Yasin Akhtar ◽

...

Keyword(s):

Healthcare Workers ◽

Tertiary Care ◽

Transmission Risk ◽

Mitigation Measures ◽

Age Group ◽

Community Transmission ◽

Mode Of Transmission ◽

Healthcare Associated ◽

Female Nurses ◽

Cardiac Center

Aim: To determine the frequency, mode of transmission, and outcome of Coronavirus Disease 2019 (COVID-19) among healthcare workers (HCWs) in a tertiary care cardiac center in the Kingdom of Saudi Arabia (KSA). Methods: This is a retrospective study of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infected HCWs and was conducted from 2 March to 31 December 2020. Data related to the presence of COVID-19 symptoms, mode of transmission, hospitalization, and mortality were collected from the patients’ medical records. Results: Of the 4462 patients tested for COVID-19 by real-time reverse transcriptase polymerase chain reaction (RT-PCR), 203 (4.5%) HCWs were positive; of these, 125 (61.6%) were males, and the most common age group was <40 years. The most commonly encountered health professionals were nurses (74, 36.4%), followed by therapists/technicians (48, 23.6%), housekeepers (25, 12.3%), and physicians (21, 10.4%). The majority (184, 90.6%) of the HCWs contracted COVID-19 in the community, and only 19 (9.4%) were healthcare-associated infections. Of the infected HCWs, 169 (83.3%) had mild symptoms and were managed in home isolation. The most common symptoms were fever (128, 63.1%), body ache (124, 61.8%), headache (113, 55.7%), dry cough (123, 60.6%), sore throat (97, 47.8%), body weakness (97, 47.8%), and fatigue (94, 46.3%). Comparing males and females, there was a significantly higher number of female nurses; in contrast, there was a higher number of male physicians, housekeepers, therapists/technicians, and other specialty HCWs. A significantly lower number of nurses, therapists/technicians were infected in the ≥40 years age group compared to <40 years. Furthermore, a significantly higher difference was observed among non-Saudi nurses compared to Saudi nurses. No mortality was documented among the included HCWs. Conclusions: In the largest tertiary cardiac center in KSA, most HCWs who contracted COVID-19 developed mild symptoms; nurses and those aged <40 years were most commonly infected, and most infections were acquired in the community. HCWs’ adherence to mitigation measures outside of the workplace is vital to curb the current pandemic and decrease nosocomial transmission risk.

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Passing the Test: A Model-based analysis of safe school-reopening strategies

10.1101/2021.01.27.21250388 ◽

2021 ◽

Cited By ~ 1

Author(s):

Alyssa Bilinski ◽

Joshua A. Salomon ◽

John Giardina ◽

Andrea Ciaranello ◽

Meagan C. Fitzpatrick

Keyword(s):

Elementary Schools ◽

High Schools ◽

Transmission Risk ◽

Mitigation Measures ◽

Single Infection ◽

Full Time ◽

Prevention Measures ◽

School Students ◽

School Based ◽

Community Transmission

AbstractBackgroundThe COVID-19 pandemic has induced historic educational disruptions. In December 2020, at least two-thirds of US public school students were not attending full-time in-person education. The Biden Administration has expressed that reopening schools is a priority.ObjectiveTo compare risks of SARS-COV-2 transmission in schools across different school-based prevention strategies and levels of community transmission.DesignWe developed an agent-based network model to simulate transmission in elementary and high school communities, including home, school, and inter-household interactions.SettingWe parameterized school structure based on average US classrooms, with elementary schools of 638 students and high schools of 1,451 students. We varied daily community incidence from 1 to 100 cases per 100,000 population.Patients (or Participants)We simulated students, faculty/staff, and adult household members.InterventionsWe evaluated isolation of symptomatic individuals, quarantine of an infected individual’s contacts, reduced class sizes, alternative schedules, staff vaccination, and weekly asymptomatic screening.MeasurementsWe projected transmission among students, staff and families during one month following introduction of a single infection into a school. We also calculated the number of infections expected for a typical 8-week quarter, contingent on community incidence rate.ResultsSchool transmission risk varies according to student age and community incidence and is substantially reduced with effective, consistent mitigation measures. Nevertheless, when transmission occurs, it may be difficult to detect without regular, frequent testing due to the subclinical nature of most infections in children. Teacher vaccination can reduce transmission to staff, while asymptomatic screening both improves understanding of local circumstances and reduces transmission, facilitating five-day schedules at full classroom capacity.LimitationsThere is uncertainty about susceptibility and infectiousness of children and low precision regarding the effectiveness of specific prevention measures, particularly with emergence of new variants.ConclusionWith controlled community transmission and moderate school-based prevention measures, elementary schools can open with few in-school transmissions, while high schools require more intensive mitigation. Asymptomatic screening should be a key component of school reopenings, allowing reopening at higher community incidence while still minimizing transmission risk.

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Employing Agent-based Modeling to Mitigate Infectious Disease Spread

Proceedings of the Human Factors and Ergonomics Society Annual Meeting ◽

10.1177/1071181321651200 ◽

2021 ◽

Vol 65 (1) ◽

pp. 390-394

Author(s):

Michael Schwartz ◽

Paul Oppold ◽

Boniface Noyongoyo ◽

Peter Hancock

Keyword(s):

Infectious Disease ◽

Viral Infections ◽

Agent Based Modeling ◽

Disease Spread ◽

Effective Measure ◽

Agent Based ◽

Personal Learning ◽

Business Operations ◽

Interpersonal Factors ◽

Reduce Risk

The current pandemic has tested systems in place as to how to fight infectious diseases in many countries. COVID-19 spreads quickly and is deadly. However, it can be controlled through different measures such as physical distancing. The current project examines through simulation model of the UCF Global building the potential spread of an infectious disease via AnyLogic Personal Learning Edition (PLE) 8.7.0 on a laptop running Windows 10. The goal is to determine the environmental and interpersonal factors that could be modified to reduce risk of illness while maintaining typical business operations. Multiple experiments were ran to see when there is a potential change in infection and spread rate. Results show that increases occur with density between 400 and 500. To curtail the spread it is therefore important to limit contact through physical distancing for it has been proven an effective measure for reducing the spread of viral infections.

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Challenges in Sharing Computer and Network Logs

Information Resources Management ◽

10.4018/978-1-61520-965-1.ch804 ◽

2010 ◽

pp. 2310-2325

Author(s):

Adam Slagell ◽

Kiran Lakkaraju

Keyword(s):

Real World ◽

Future Research ◽

The Past ◽

Trade Offs ◽

Reduce Risk ◽

Share Information ◽

Made In

It is desirable for many reasons to share information, particularly computer and network logs. Researchers need it for experiments, incident responders need it for collaborative security, and educators need this data for real world examples. However, the sensitive nature of this information often prevents its sharing. Anonymization techniques have been developed in recent years that help reduce risk and navigate the trade-offs between privacy, security and the need to openly share information. This chapter looks at the progress made in this area of research over the past several years, identifies the major problems left to solve and sets a roadmap for future research.

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Prevalence and risk factors for in-school transmission of SARS-CoV-2 in Massachusetts K-12 public schools, 2020-2021

10.1101/2021.09.22.21263900 ◽

2021 ◽

Author(s):

Sandra B Nelson ◽

Caitlin Dugdale ◽

Alyssa Bilinski ◽

Duru Cosar ◽

Nira L Pollock ◽

...

Keyword(s):

Public Schools ◽

Index Case ◽

Transmission Risk ◽

Mitigation Measures ◽

Contact Tracing ◽

Convenience Sample ◽

School Based ◽

Increased Risk ◽

K 12 ◽

Index Cases

Introduction The SARS-CoV-2 secondary attack rate (SAR) in schools is low when mitigation measures are adopted, Data on the relative impact of such strategies are limited. We evaluated the SARS-CoV-2 SAR in Massachusetts schools during 2020-21 and factors associated with transmission risk. Methods: In a convenience sample of 25 Massachusetts public K-12 school districts, de-identified information about SARS-CoV-2 cases and their school-based contacts was reported using a standardized contact-tracing tool. Index cases were included if they were in school while infectious. SAR was defined as the proportion of in-school contacts acquiring SARS-CoV-2 infection and designated as possible or probable in-school transmission by school-based teams. We compared exposure-specific SAR using unadjusted risk ratios (RR) with 95% confidence intervals (CI); p-values were calculated using Fishers exact tests. Results Eight districts (70 schools with >33,000 enrolled students) participated. There were 435 index cases and 1,771 school-based contacts (Table 1). Most contacts (1327/1771 [75%]) underwent SARS-CoV-2 testing and 39/1327 (2.9%) contacts tested positive. Of 39 positive contacts, 10 (25.6%) had clear out-of-school exposures and were deemed not in-school transmissions, so were excluded from further calculations. Twenty-nine (74.4%) contacts were deemed possible or probable in-school transmissions, resulting in an in-school SAR of 2.2%. Of the 29 in-school transmissions, 6 (20.7%) were staff-to-staff, 7 (24.1%) were staff-to-student, 3 (10.3%) were student-to-staff, and 13 (44.8%) were student-to-student; 6 (20.7%) occurred from index cases attending work/school while symptomatic. The unadjusted SAR (Table 2) was significantly higher if the index case was a staff member versus a student (RR 2.18, 95% CI 1.06-4.49; p=0.030), if the index case was identified via in-school contact tracing versus via school-based asymptomatic testing (RR 8.44, 95% CI 1.98-36.06; p=0.001), if the exposure occurred at lunch versus elsewhere (RR 5.74, 95% CI 2.11-15.63; p<0.001; all lunch transmissions were staff-to-staff), and if both parties were unmasked versus both masked (RR 6.98, 95% CI 3.09-15.77; p<0.001). For students, SAR did not differ by grade level. Conclusions Secondary attack rates for SARS-CoV-2 were low in public school settings with comprehensive mitigation measures in place before the emergence of the delta variant; lack of masking and staff-to-staff dining were associated with increased risk.

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A mechanistic, stigmergy model of territory formation in asocial animals: Territorial behavior can dampen disease prevalence but increase persistence

10.1101/796045 ◽

2019 ◽

Author(s):

Lauren A. White ◽

Sue VandeWoude ◽

Meggan E. Craft

Keyword(s):

Disease Ecology ◽

Scent Marking ◽

Movement Ecology ◽

Pathogen Transmission ◽

Disease Spread ◽

Movement Behavior ◽

Infectious Period ◽

Trade Offs ◽

Animal Populations ◽

Territory Formation

AbstractMechanistic portrayals of how animals form and maintain territories remain rare, and as a discipline, collective movement ecology has tended to focus on synergistic (e.g., migration, shoaling) rather than agonistic or territorial interactions. Here we ask how dynamic territory formation and maintenance might contribute to disease dynamics in an asocial territorial animal for an indirectly transmitted pathogen. We developed a mechanistic individual-based model where stigmergy—the deposition of signals into the environment (e.g., scent marking, scraping)—dictates not only local movement choices and long-term territory formation, but also the risk of pathogen transmission. Based on a variable importance analysis, the length of the infectious period was the single most important variable in predicting outbreak success, maximum prevalence, and outbreak duration. Population size and rate of pathogen decay were also key predictors. We found that territoriality best reduced maximum prevalence in conditions where we would otherwise expect outbreaks to be most successful: slower recovery rates (i.e., longer infectious periods) and higher conspecific densities. However, at high enough densities, outbreak duration became considerably more variable. Our findings therefore support a limited version of the “territoriality benefits” hypothesis—where reduced home range overlap leads to reduced opportunities for pathogen transmission, but with the caveat that reduction in outbreak severity may increase the likelihood of pathogen persistence. For longer infectious periods and higher host densities, key trade-offs emerged between the strength of pathogen load, strength of the stigmergy cue, and the rate at which those two quantities decayed; this finding raises interesting questions about the evolutionary nature of these competing processes and the role of possible feedbacks between parasitism and territoriality. This work also highlights the importance of considering social cues as part of the movement landscape in order to improve our understanding of the consequences of individual behaviors on population level outcomes.Author summaryMaking decisions about conservation and disease management relies on our understanding of what allows animal populations to be successful. However, movement ecology, as a field, tends to focus on how animals respond to their abiotic environment. Similarly, disease ecology often focuses on the social behavior of animals without accounting for their individual movement patterns. We developed a simulation model that bridges these two fields by allowing hosts to inform their movement based on the past trajectories of other hosts. As hosts navigate their environment, they leave behind a scent trail while avoiding the scent trails of other individuals. We wanted to know if this means of territory formation could heighten or dampen disease spread when infectious hosts leave pathogens in their wake. We found that territoriality could inhibit disease spread under conditions that we would normally expect pathogens to be most successful: where there are many hosts on the landscape and hosts stay infectious for longer. This work points to how incorporating movement behavior into disease models can provide improved understanding of how diseases spread in wildlife populations; such understanding is particularly important in the face of combatting ongoing and emerging infectious diseases.

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Mitigating Resource Management Related Factors Affecting Time and Cost Performance in Construction Projects

Pakistan Journal of Engineering and Technology ◽

10.51846/vol4iss2pp62-66 ◽

2021 ◽

Vol 4 (2) ◽

pp. 62-66

Author(s):

Abdul Qadir Memon ◽

Aftab Hameed Memon ◽

Mohsin Ali Soomro

Keyword(s):

Construction Projects ◽

Poor Performance ◽

Mitigation Measures ◽

Construction Time ◽

Related Factors ◽

Cost Performance ◽

Effective Measure ◽

Significance Level ◽

Factors Affecting ◽

Factors Affecting Performance

Construction time and cost are basic parameters for measuring project performance. Unfortunately, construction projects are facing poor time and cost performance globally. This poor performance is occurred due to several factors among which resource related factors play very important role. Hence, it is very essential to control the factors affecting performance of time and cost. This study assessed significance level of the resource related factors and determined effective measure to mitigate the factors. Gathering of data was done by questionnaire survey with the practitioners representing client, consultant and contractors involved in handling execution works. Statistical analysis of gathered responses revealed that High cost of machinery and its maintenance; and fluctuation of prices of materials on site are significant resource related factors affecting project cost performance while in affecting time performance, the significant factors are financial difficulties faced by contractors and high cost of machinery and its maintenance. This study also assessed the effectiveness level of the mitigation measures for improving time and cost performance. The findings of this study will be helpful for the practitioners to make necessary arrangement for improving time and cost performance.

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