scholarly journals Fundamental Limitations of Contact Tracing for COVID-19

2020 ◽  
Author(s):  
P. Tupper ◽  
S. Otto ◽  
C. Colijn
Keyword(s):  
High Risk ◽  
Exponential Growth ◽  
Contact Tracing ◽  
Loss Of Control ◽  
Social Distancing ◽  
Pooled Testing ◽  
Fundamental Limitations ◽  
Travel Restrictions ◽  
Asymptomatic Individuals

AbstractContact tracing has played a central role in COVID-19 control in many jurisdictions and is often used in conjunction with other measures such as travel restrictions and social distancing mandates. Contact tracing is made ineffective, however, by delays in testing, calling, and isolating. Even if delays are minimized, contact tracing can only prevent a fraction of onward transmissions from contacts. Without other measures in place, contact tracing alone is insufficient to prevent exponential growth in the number of cases. Even when used effectively with other measures, occasional bursts in call loads can overwhelm contact tracing systems and lead to a loss of control. We propose embracing approaches to COVID-19 control that broadly test individuals without symptoms, in whatever way is economically feasible – either with fast cheap tests that can be deployed widely, with pooled testing, or with screening of judiciously chosen groups of high-risk individuals. Only by ramping up testing of asymptomatic individuals can we avoid the inherent delays that limit the efficacy of contact tracing.

scholarly journals Fundamental limitations of contact tracing for COVID-19

FACETS ◽  
2021 ◽  
Vol 6 ◽  
pp. 1993-2001
Author(s):  
Paul Tupper ◽  
Sarah P. Otto ◽  
Caroline Colijn
Keyword(s):  
High Risk ◽  
Exponential Growth ◽  
Contact Tracing ◽  
Loss Of Control ◽  
Social Distancing ◽  
Pooled Testing ◽  
Fundamental Limitations ◽  
Travel Restrictions

Contact tracing has played a central role in COVID-19 control in many jurisdictions and is often used in conjunction with other measures such as travel restrictions and social distancing mandates. Contact tracing is made ineffective, however, by delays in testing, calling, and isolating. Even if delays are minimized, contact tracing triggered by testing of symptomatic individuals can only prevent a fraction of onward transmissions from contacts. Without other measures in place, contact tracing alone is insufficient to prevent exponential growth in the number of cases in a population with little immunity. Even when used effectively with other measures, occasional bursts in call loads can overwhelm contact tracing systems and lead to a loss of control. We propose embracing approaches to COVID-19 contact tracing that broadly test individuals without symptoms, in whatever way is economically feasible—either with fast and cheap tests that can be deployed widely, with pooled testing, or with screening of judiciously chosen groups of high-risk individuals. These considerations are important both in regions where widespread vaccination has been deployed and in those where few residents have been immunized.

scholarly journals Impact of Social Distancing and Travel Restrictions on Non–Coronavirus Disease 2019 (Non–COVID-19) Respiratory Hospital Admissions in Young Children in Rural Alaska

2020 ◽  
Author(s):  
Leisha D Nolen ◽  
Sara Seeman ◽  
Dana Bruden ◽  
Joe Klejka ◽  
Chris Desnoyers ◽  
...  
Keyword(s):  
High Risk ◽  
Young Children ◽  
Hospital Admissions ◽  
High Risk Population ◽  
Respiratory Illnesses ◽  
Social Distancing ◽  
The Past ◽  
Secondary Benefits ◽  
Rural Alaska ◽  
Travel Restrictions

Abstract Hospitalizations due to non-coronavirus disease 2019 (non-COVID-19) respiratory illnesses decreased dramatically after social distancing was implemented in a high-risk population in rural Alaska; an unprecedented decline compared to the past 10 respiratory seasons. This demonstrates the potential secondary benefits of implementing social distancing and travel restrictions on respiratory illnesses.

scholarly journals Downsizing of contact tracing during COVID-19 vaccine roll-out

2021 ◽  
Author(s):  
Maria M Martignoni ◽  
Joshua Renault ◽  
Joseph Baafi ◽  
Amy Hurford
Keyword(s):  
Exponential Growth ◽  
Cost Effective ◽  
Quantitative Information ◽  
Vaccination Status ◽  
Outbreak Detection ◽  
Contact Tracing ◽  
Epidemic Spread ◽  
Social Distancing ◽  
The Impact ◽  
Roll Out

Contact tracing is a key component of successful management of COVID-19. Contacts of infected individuals are asked to quarantine, which can significantly slow down (or prevent) community spread. Contact tracing is particularly effective when infections are detected quickly (e.g., through rapid testing), when contacts are traced with high probability, when the initial number of cases is low, and when social distancing and border restrictions are in place. However, the magnitude of the individual contribution of these factors in reducing epidemic spread and the impact of vaccination in determining contact tracing outputs is not fully understood. We present a delayed differential equation model to investigate how vaccine roll-out and the relaxation of social distancing requirements affect contact tracing practises. We provide an analytical criteria to determine the minimal contact tracing efficiency (defined as the the probability of identifying and quarantining contacts of symptomatic individuals) required to keep an outbreak under control, with respect to the contact rate and vaccination status of the population. Additionally, we consider how delays in outbreak detection and increased case importation rates affect the number of contacts to be traced daily. We show that in vaccinated communities a lower contact tracing efficiency is required to avoid uncontrolled epidemic spread, and delayed outbreak detection and relaxation of border restrictions do not lead to a significantly higher risk of overwhelming contact tracing. We find that investing in testing programs, rather than increasing the contact tracing capacity, has a larger impact in determining whether an outbreak will be controllable. This is because early detection activates contact tracing, which will slow, and eventually reverse exponential growth, while the contact tracing capacity is a threshold that will easily become overwhelmed if exponential growth is not curbed. Finally, we evaluate quarantine effectiveness during vaccine roll-out, by considering the proportion of people that will develop an infection while in isolation in relation to the vaccination status of the population and for different viral variants. We show that quarantine effectiveness decreases with increasing proportion of fully vaccinated individuals, and increases in the presence of more transmissible variants. These results suggest that a cost-effective approach during vaccine roll-out is to establish different quarantine rules for vaccinated and unvaccinated individuals, where rules should depend on viral transmissibility. Altogether, our study provides quantitative information for contact tracing downsizing during vaccine roll-out, to guide COVID-19 exit strategies.

scholarly journals An evaluation of COVID-19 transmission control in Wenzhou using a modified SEIR model

2021 ◽  
Vol 149 ◽  
Author(s):  
Wenning Li ◽  
Jianhua Gong ◽  
Jieping Zhou ◽  
Lihui Zhang ◽  
Dongchuan Wang ◽  
...  
Keyword(s):  
Emergency Preparedness ◽  
Close Contact ◽  
Control Measures ◽  
Contact Tracing ◽  
Seir Model ◽  
Social Distancing ◽  
Infected People ◽  
Travel Restrictions ◽  
Developmental Characteristics ◽  
Novel Coronavirus

Abstract In December 2019, the first confirmed case of pneumonia caused by a novel coronavirus was reported. Coronavirus disease 2019 (COVID-19) is currently spreading around the world. The relationships among the pandemic and its associated travel restrictions, social distancing measures, contact tracing, mask-wearing habits and medical consultation efficiency have not yet been extensively assessed. Based on the epidemic data reported by the Health Commission of Wenzhou, we analysed the developmental characteristics of the epidemic and modified the Susceptible-Exposed-Infectious-Removed (SEIR) model in three discrete ways. (1) According to the implemented preventive measures, the epidemic was divided into three stages: initial, outbreak and controlled. (2) We added many factors, such as health protections, travel restrictions and social distancing, close-contact tracing and the time from symptom onset to hospitalisation (TSOH), to the model. (3) Exposed and infected people were subdivided into isolated and free-moving populations. For the parameter estimation of the model, the average TSOH and daily cured cases, deaths and imported cases can be obtained through individual data from epidemiological investigations. The changes in daily contacts are simulated using the intracity travel intensity (ICTI) from the Baidu Migration Big Data platform. The optimal values of the remaining parameters are calculated by the grid search method. With this model, we calculated the sensitivity of the control measures with regard to the prevention of the spread of the epidemic by simulating the number of infected people in various hypothetical situations. Simultaneously, through a simulation of a second epidemic, the challenges from the rebound of the epidemic were analysed, and prevention and control recommendations were made. The results show that the modified SEIR model can effectively simulate the spread of COVID-19 in Wenzhou. The policy of the lockdown of Wuhan, the launch of the first-level Public Health Emergency Preparedness measures on 23 January 2020 and the implementation of resident travel control measures on 31 January 2020 were crucial to COVID-19 control.

scholarly journals Control of a Nosocomial Outbreak of COVID-19 in a University Hospital

2020 ◽  
Vol 7 (12) ◽  
Author(s):  
Sei Harada ◽  
Shunsuke Uno ◽  
Takayuki Ando ◽  
Miho Iida ◽  
Yaoko Takano ◽  
...  
Keyword(s):  
High Risk ◽  
Large Scale ◽  
Secondary Infection ◽  
Control Measures ◽  
University Hospital ◽  
Contact Tracing ◽  
Effective Control ◽  
Primary Case ◽  
Pcr Screening ◽  
Social Distancing

Abstract Background Nosocomial spread of coronavirus disease 2019 (COVID-19) causes clusters of infection among high-risk individuals. Controlling this spread is critical to reducing COVID-19 morbidity and mortality. We describe an outbreak of COVID-19 in Keio University Hospital, Japan, and its control and propose effective control measures. Methods When an outbreak was suspected, immediate isolation and thorough polymerase chain reaction (PCR) testing of patients and health care workers (HCWs) using an in-house system, together with extensive contact tracing and social distancing measures, were conducted. Nosocomial infections (NIs) were defined as having an onset or positive test after the fifth day of admission for patients and having high-risk contacts in our hospital for HCWs. We performed descriptive analyses for this outbreak. Results Between March 24 and April 24, 2020, 27 of 562 tested patients were confirmed positive, of whom 5 (18.5%) were suspected as NIs. For HCWs, 52 of 697 tested positive, and 40 (76.9%) were considered NIs. Among transmissions, 95.5% were suspected of having occurred during the asymptomatic period. Large-scale isolation and testing at the first sign of outbreak terminated NIs. The number of secondary cases directly generated by a single primary case found before March 31 was 1.74, compared with 0 after April 1. Only 4 of 28 primary cases generated definite secondary infection; these were all asymptomatic. Conclusions Viral shedding from asymptomatic cases played a major role in NIs. PCR screening of asymptomatic individuals helped clarify the pattern of spread. Immediate large-scale isolation, contact tracing, and social distancing measures were essential to containing outbreaks.

scholarly journals Non-pharmaceutical interventions for containment, mitigation and suppression of COVID-19 infection

2020 ◽  
pp. 1-25
Author(s):  
Daniel F. Patiño-Lugo ◽  
Marcela Velez ◽  
Pamela Velásquez Salazar ◽  
Claudia Yaneth Vera-Giraldo ◽  
Viviana Vélez ◽  
...  
Keyword(s):  
Health Care Services ◽  
Social Impact ◽  
Scientific Evidence ◽  
Policy Decision ◽  
Substantial Effect ◽  
Contact Tracing ◽  
Social Distancing ◽  
First Case ◽  
Travel Restrictions ◽  
Pharmaceutical Interventions

The best available scientific evidence is required to design effective non-pharmaceutical interventions (NPIs) to help policymakers to contain COVID-19 outbreaks. The aim of this review is to describe which NPIs used different countries and a when they use them. It also explores how NPIs impact the number of cases, the mortality, and the capacity of health systems. We consulted eight web pages of transnational organizations, 17 of international media, 99 of government institutions in the 19 countries included, and besides, we included nine studies (out of 34 identified) that met inclusion criteria. We found that some countries are focused on establishing travel restrictions, isolation of identified cases, and high-risk people. Others have a more intense combination of mandatory quarantine and other drastic social distancing measures. Some countries have implemented interventions in the first fifteen days after detecting the first case, while others have taken more than 30 days. The effectiveness of isolated NPIs may be limited, but combined interventions have shown to be effective in reducing the transmissibility of the disease, the collapse of health care services, and mortality. When the number of new cases has been controlled, it is necessary to maintain social distancing measures, self-isolation, and contact tracing for several months. The policy decision-making in this time should be aimed to optimize the opportunities of saving lives, reducing the collapse of health services, and minimizing the economic and social impact over the general population, but principally over the most vulnerable. The timing of implementing and lifting interventions is likely to have a substantial effect on those objectives.

scholarly journals An overview of basics for developing a reopening roadmap amid COVID-19 pandemic, a suggestion for the world

2020 ◽  
Author(s):  
Mehrdad Askarian ◽  
Gary Groot ◽  
Ehsan Taherifard ◽  
Erfan Taherifard ◽  
Hossein Akbarialiabad ◽  
...  
Keyword(s):  
High Risk ◽  
Health System ◽  
Risk Groups ◽  
System Capacity ◽  
Contact Tracing ◽  
Social Distancing ◽  
Epidemiological Monitoring ◽  
Preventive Actions ◽  
The World ◽  
Previous Phase

Abstract The necessity of easing pandemic restrictions is apparent, and due to the harsh consequences of lockdowns, governments are willing to find a rational pathway to reopen their activities. To find out the basics of developing a reopening roadmap, we reviewed 16 roadmaps. The most notable findings are as following: Protecting the high-risk groups, increasing testing and contact tracing capacity, making decisions scientifically, and making the decisions to impose the lowest risks to the economy were the most principles mentioned in the roadmaps. Social distancing, using a face-covering mask, and washing hands were the necessary preventive actions that were recommended for individuals. Health key metrics pointed out in the roadmaps were categorized into four subsets; sufficient preventive capacities, appropriate diagnosis capacity, appropriate epidemiological monitoring capacity, and sufficient health system capacity to be resilient in facing the surges and next phases of the pandemic. All roadmaps describe their in-phases strategy in three major steps, with a minimum of two weeks considered for each phase. Based on the health key metrics, most of the roadmaps noted when progressing to the next phases, while some of them did not focus on the criteria of returning to the previous phase; which may alter the dynamicity of a roadmap.

scholarly journals Coronavirus Disease Pandemic: A Public Health Perspective

2020 ◽  
pp. 1-7
Author(s):  
Gundu H R Rao ◽  
Keyword(s):  
High Risk ◽  
Long Term Care ◽  
Phase 1 ◽  
Herd Immunity ◽  
Contact Tracing ◽  
Public Health Perspective ◽  
Term Care ◽  
Social Distancing ◽  
Care Facilities

The new novel coronavirus was discovered by a Scottish virologist in London in 1964. As is usual with new discoveries, it seems the article she wrote about this discovery, was rejected by a peer reviewed journal. Dr Almeida wrote to the prestigious journal Nature (Nature 220, 1968), outlining her findings and proposed the name “coronavirus” for the new family of viruses. The name referred to the “crown like” appearance, she first observed on these viruses by electron microscopy. While SARS CoV-2 infection seems to be in control in China (less than 100,000 for a population of over billion), where it originated, the epidemic has moved briskly to the rest of the world. What seemed to be impossible to achieve, - imposing and enforcing strict quarantine of people, -is now a reality in majority of the countries. Success of preventive efforts is related, to how best the key principles of prevention strategies are followed; testing for infection, contact tracing, social distancing, wearing masks, and containment of the infected individuals. In December of 2019, several people in Wuhan, China, developed pneumonia and respiratory failure, like what happened during SARS epidemic of 2003. This virus is easily transmissible by symptomatic as well as asymptomatic individuals. As early as January 2020, SARS CoV-2 virus was found to spread during workshops, company meetings. Hospitals seem to provide a favorable environment for the propagation of coronavirus disease(Covid-19). Long-term care facilities are high-risk settings for infections of respiratory diseases. In the long-term care facilities, majority of the senior citizens, seem to have pre-existing conditions, such as hypertension, obesity, type-2 diabetes or cardiovascular diseases, which puts them at high-risk associated with Covid-19 severity. Several mass gatherings have been associated with explosive outbreaks of Covid-19, including political rallies, protests, sports and entertainment events. The possible role of children in transmission of the coronavirus is still not clear. Several individuals who had recovered from the COVID-19 have tested positive again at a later date, suggesting that the infection has been reactivated. These observations raise question about immunity in covid-19 patients for future infections, as well as the ‘herd immunity’ that we all are hoping for. In the absence of an evidence-based cure, the only choice we have of preventing infection is social distancing, wearing masks where needed, hand washing, contact tracing, and containment. SARS CoV-2 virus spreads through a receptor called angiotensin(ACE 2), which is expressed on many cells including the nasopharyngeal epithelial cells, by attaching to these receptors via its spike like external projections.In view of this observation, there is considerable interest in interventions, that may prevent these interactions including vaccines. The mRNA-1273 Group members have published their preliminary report in NEJM (July 14, 2020) about the successful completion of a phase-1 study of 45 healthy adults, who received two vaccines containing stabilized perfusion of SARS CoV-2 spike protein. The vaccines seem to have induced the SARS CoV-2 immune response in all participants. These preliminary findings, support and encourage the development of such novel vaccines, as well as drugs that interfere with the host receptor and virus interaction

Are social networking platforms the key to effective social distancing for COVID-19? (Preprint)

2020 ◽  
Author(s):  
Viknesh Sounderajah ◽  
Hutan Ashrafian ◽  
Sheraz Markar ◽  
Ara Darzi
Keyword(s):  
Operating System ◽  
Social Networking ◽  
Contact Tracing ◽  
Text Data ◽  
Social Distancing ◽  
Web Mapping ◽  
Viral Spread ◽  
Behavioural Insights ◽  
Mapping Software ◽  
Incidence And Mortality

UNSTRUCTURED If health systems are to effectively employ social distancing measures to in response to further COVID-19 peaks, they must adopt new behavioural metrics that can supplement traditional downstream measures, such as incidence and mortality. Access to mobile digital innovations may dynamically quantify compliance to social distancing (e.g. web mapping software) as well as establish personalised real-time contact tracing of viral spread (e.g. mobile operating system infrastructure through Google-Apple partnership). In particular, text data from social networking platforms can be mined for unique behavioural insights, such as symptom tracking and perception monitoring. Platforms, such as Twitter, have shown significant promise in tracking communicable pandemics. As such, it is critical that social networking companies collaborate with each other in order to (1) enrich the data that is available for analysis, (2) promote the creation of open access datasets for researchers and (3) cultivate relationships with governments in order to affect positive change.

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