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1.
BMJ ; 372: n608, 2021 03 31.
Artigo em Inglês | MEDLINE | ID: mdl-33789843

RESUMO

OBJECTIVE: To investigate rates of adherence to the UK's test, trace, and isolate system over the initial 11 months of the covid-19 pandemic. DESIGN: Series of cross sectional online surveys. SETTING: 37 nationally representative surveys in the UK, 2 March 2020 to 27 January 2021. PARTICIPANTS: 74 697 responses from 53 880 people living in the UK, aged 16 years or older (37 survey waves, about 2000 participants in each wave). MAIN OUTCOME MEASURES: Identification of the main symptoms of covid-19 (cough, high temperature or fever, and loss of sense of smell or taste), self-reported adherence to self-isolation if symptoms were present and intention to self-isolate if symptoms were to develop, requesting a test for covid-19 if symptoms were present and intention to request a test if symptoms were to develop, and intention to share details of close contacts. RESULTS: Only 51.5% of participants (95% confidence interval 51.0% to 51.9%, n=26 030/50 570) identified the main symptoms of covid-19; the corresponding values in the most recent wave of data collection (25-27 January 2021) were 50.8% (48.6% to 53.0%, n=1019/2007). Across all waves, duration adjusted adherence to full self-isolation was 42.5% (95% confidence interval 39.7% to 45.2%, n=515/1213); in the most recent wave of data collection (25-27 January 2021), it was 51.8% (40.8% to 62.8%, n=43/83). Across all waves, requesting a test for covid-19 was 18.0% (95% confidence interval 16.6% to 19.3%, n=552/3068), increasing to 22.2% (14.6% to 29.9%, n=26/117) from 25 to 27 January. Across all waves, intention to share details of close contacts was 79.1% (95% confidence interval 78.8% to 79.5%, n=36 145/45 680), increasing to 81.9% (80.1% to 83.6%, n=1547/1890) from 25 to 27 January. Non-adherence was associated with being male, younger age, having a dependent child in the household, lower socioeconomic grade, greater financial hardship during the pandemic, and working in a key sector. CONCLUSIONS: Levels of adherence to test, trace, and isolate are low, although some improvement has occurred over time. Practical support and financial reimbursement are likely to improve adherence. Targeting messaging and policies to men, younger age groups, and key workers might also be necessary.


Assuntos
/estatística & dados numéricos , Busca de Comunicante/estatística & dados numéricos , Isolamento Social , Adulto , Idoso , Estudos Transversais , Feminino , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Masculino , Pessoa de Meia-Idade , Pandemias , Inquéritos e Questionários , Reino Unido/epidemiologia
2.
Proc Natl Acad Sci U S A ; 118(14)2021 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-33741734

RESUMO

Increasing evidence indicates that superspreading plays a dominant role in COVID-19 transmission. Recent estimates suggest that the dispersion parameter k for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is on the order of 0.1, which corresponds to about 10% of cases being the source of 80% of infections. To investigate how overdispersion might affect the outcome of various mitigation strategies, we developed an agent-based model with a social network that allows transmission through contact in three sectors: "close" (a small, unchanging group of mutual contacts as might be found in a household), "regular" (a larger, unchanging group as might be found in a workplace or school), and "random" (drawn from the entire model population and not repeated regularly). We assigned individual infectivity from a gamma distribution with dispersion parameter k We found that when k was low (i.e., greater heterogeneity, more superspreading events), reducing random sector contacts had a far greater impact on the epidemic trajectory than did reducing regular contacts; when k was high (i.e., less heterogeneity, no superspreading events), that difference disappeared. These results suggest that overdispersion of COVID-19 transmission gives the virus an Achilles' heel: Reducing contacts between people who do not regularly meet would substantially reduce the pandemic, while reducing repeated contacts in defined social groups would be less effective.


Assuntos
/epidemiologia , Busca de Comunicante/estatística & dados numéricos , Modelos Estatísticos , Pandemias , Fatores Etários , /virologia , Simulação por Computador , Humanos , Quarentena/estatística & dados numéricos , /fisiologia , Rede Social
4.
Nat Commun ; 12(1): 1655, 2021 03 12.
Artigo em Inglês | MEDLINE | ID: mdl-33712583

RESUMO

Digital contact tracing is a relevant tool to control infectious disease outbreaks, including the COVID-19 epidemic. Early work evaluating digital contact tracing omitted important features and heterogeneities of real-world contact patterns influencing contagion dynamics. We fill this gap with a modeling framework informed by empirical high-resolution contact data to analyze the impact of digital contact tracing in the COVID-19 pandemic. We investigate how well contact tracing apps, coupled with the quarantine of identified contacts, can mitigate the spread in real environments. We find that restrictive policies are more effective in containing the epidemic but come at the cost of unnecessary large-scale quarantines. Policy evaluation through their efficiency and cost results in optimized solutions which only consider contacts longer than 15-20 minutes and closer than 2-3 meters to be at risk. Our results show that isolation and tracing can help control re-emerging outbreaks when some conditions are met: (i) a reduction of the reproductive number through masks and physical distance; (ii) a low-delay isolation of infected individuals; (iii) a high compliance. Finally, we observe the inefficacy of a less privacy-preserving tracing involving second order contacts. Our results may inform digital contact tracing efforts currently being implemented across several countries worldwide.


Assuntos
/prevenção & controle , Busca de Comunicante/métodos , Pandemias , Número Básico de Reprodução/prevenção & controle , Número Básico de Reprodução/estatística & dados numéricos , /transmissão , Simulação por Computador , Busca de Comunicante/estatística & dados numéricos , Humanos , Modelos Estatísticos , Pandemias/prevenção & controle , Pandemias/estatística & dados numéricos , Privacidade , Quarentena/métodos , Quarentena/estatística & dados numéricos , Fatores de Risco
5.
N Z Med J ; 134(1531): 67-76, 2021 03 26.
Artigo em Inglês | MEDLINE | ID: mdl-33767478

RESUMO

AIMS: To assess how well the NZ COVID Tracer QR (Quick Response) code poster is displayed by Dunedin businesses and other venues in which groups of people gather indoors, and to calculate the proportions of visitors to those venues who scan the QR code poster. METHODS: We randomly selected 10 cafes, 10 restaurants, 10 bars, five churches, and five supermarkets and visited them at their busiest times. We evaluated the display of QR code posters using a six-item assessment tool that was based on guidance provided to businesses and services by the Ministry of Health, and we counted the number of people who entered each venue during a one-hour period and the number who scanned the QR code poster. RESULTS: All six criteria for displaying QR code posters were met at half of the hospitality venues, four of five churches, and all supermarkets. Scanning proportions were low at all venues (median 10.2%), and at 12 (30%) no visitors scanned; eight of these venues were bars. CONCLUSION: This audit provides a snapshot of the display and scanning of QR code posters in a city with no managed isolation and quarantine facilities and where no COVID-19 cases have been detected for 10 months.


Assuntos
Busca de Comunicante , Apresentação de Dados , Instalações não Médicas Públicas e Privadas , Pôsteres como Assunto , Adulto , /prevenção & controle , Busca de Comunicante/métodos , Busca de Comunicante/estatística & dados numéricos , Apresentação de Dados/normas , Apresentação de Dados/estatística & dados numéricos , Feminino , Humanos , Masculino , Auditoria Administrativa , Marketing/normas , Nova Zelândia/epidemiologia , Instalações não Médicas Públicas e Privadas/organização & administração , Instalações não Médicas Públicas e Privadas/normas , Instalações não Médicas Públicas e Privadas/estatística & dados numéricos , Avaliação de Resultados em Cuidados de Saúde , Saúde Pública/métodos
6.
PLoS One ; 16(3): e0247614, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33788852

RESUMO

Efficient contact tracing and testing are fundamental tools to contain the transmission of SARS-CoV-2. We used multi-agent simulations to estimate the daily testing capacity required to find and isolate a number of infected agents sufficient to break the chain of transmission of SARS-CoV-2, so decreasing the risk of new waves of infections. Depending on the non-pharmaceutical mitigation policies in place, the size of secondary infection clusters allowed or the percentage of asymptomatic and paucisymptomatic (i.e., subclinical) infections, we estimated that the daily testing capacity required to contain the disease varies between 0.7 and 9.1 tests per thousand agents in the population. However, we also found that if contact tracing and testing efficacy dropped below 60% (e.g. due to false negatives or reduced tracing capability), the number of new daily infections did not always decrease and could even increase exponentially, irrespective of the testing capacity. Under these conditions, we show that population-level information about geographical distribution and travel behaviour could inform sampling policies to aid a successful containment, while avoiding concerns about government-controlled mass surveillance.


Assuntos
/estatística & dados numéricos , /epidemiologia , Busca de Comunicante/estatística & dados numéricos , Modelos Estatísticos , Políticas , Quarentena/estatística & dados numéricos , /prevenção & controle , Humanos
7.
PLoS Comput Biol ; 17(3): e1008776, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33661890

RESUMO

In an epidemic, individuals can widely differ in the way they spread the infection depending on their age or on the number of days they have been infected for. In the absence of pharmaceutical interventions such as a vaccine or treatment, non-pharmaceutical interventions (e.g. physical or social distancing) are essential to mitigate the pandemic. We develop an original approach to identify the optimal age-stratified control strategy to implement as a function of the time since the onset of the epidemic. This is based on a model with a double continuous structure in terms of host age and time since infection. By applying optimal control theory to this model, we identify a solution that minimizes deaths and costs associated with the implementation of the control strategy itself. We also implement this strategy for three countries with contrasted age distributions (Burkina-Faso, France, and Vietnam). Overall, the optimal strategy varies throughout the epidemic, with a more intense control early on, and depending on host age, with a stronger control for the older population, except in the scenario where the cost associated with the control is low. In the latter scenario, we find strong differences across countries because the control extends to the younger population for France and Vietnam 2 to 3 months after the onset of the epidemic, but not for Burkina Faso. Finally, we show that the optimal control strategy strongly outperforms a constant uniform control exerted over the whole population or over its younger fraction. This improved understanding of the effect of age-based control interventions opens new perspectives for the field, especially for age-based contact tracing.


Assuntos
/epidemiologia , Modelos Biológicos , Pandemias/prevenção & controle , Adolescente , Adulto , Distribuição por Idade , Idoso , Idoso de 80 Anos ou mais , Número Básico de Reprodução/estatística & dados numéricos , Burkina Faso/epidemiologia , Criança , Pré-Escolar , Controle de Doenças Transmissíveis/métodos , Controle de Doenças Transmissíveis/estatística & dados numéricos , Biologia Computacional , Busca de Comunicante/métodos , Busca de Comunicante/estatística & dados numéricos , Feminino , França/epidemiologia , Humanos , Lactente , Recém-Nascido , Masculino , Conceitos Matemáticos , Pessoa de Meia-Idade , Modelos Estatísticos , Pandemias/estatística & dados numéricos , Vietnã/epidemiologia , Adulto Jovem
8.
PLoS Comput Biol ; 17(3): e1008633, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33661888

RESUMO

Existing compartmental mathematical modelling methods for epidemics, such as SEIR models, cannot accurately represent effects of contact tracing. This makes them inappropriate for evaluating testing and contact tracing strategies to contain an outbreak. An alternative used in practice is the application of agent- or individual-based models (ABM). However ABMs are complex, less well-understood and much more computationally expensive. This paper presents a new method for accurately including the effects of Testing, contact-Tracing and Isolation (TTI) strategies in standard compartmental models. We derive our method using a careful probabilistic argument to show how contact tracing at the individual level is reflected in aggregate on the population level. We show that the resultant SEIR-TTI model accurately approximates the behaviour of a mechanistic agent-based model at far less computational cost. The computational efficiency is such that it can be easily and cheaply used for exploratory modelling to quantify the required levels of testing and tracing, alone and with other interventions, to assist adaptive planning for managing disease outbreaks.


Assuntos
/métodos , /epidemiologia , Busca de Comunicante/métodos , Epidemias , Modelos Biológicos , Quarentena/métodos , Número Básico de Reprodução/estatística & dados numéricos , /estatística & dados numéricos , Biologia Computacional , Simulação por Computador , Busca de Comunicante/estatística & dados numéricos , Epidemias/estatística & dados numéricos , Humanos , Conceitos Matemáticos , Modelos Estatísticos , Quarentena/estatística & dados numéricos , Análise de Sistemas
9.
PLoS Comput Biol ; 17(3): e1008688, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33690626

RESUMO

Outbreaks of SARS-CoV-2 are threatening the health care systems of several countries around the world. The initial control of SARS-CoV-2 epidemics relied on non-pharmaceutical interventions, such as social distancing, teleworking, mouth masks and contact tracing. However, as pre-symptomatic transmission remains an important driver of the epidemic, contact tracing efforts struggle to fully control SARS-CoV-2 epidemics. Therefore, in this work, we investigate to what extent the use of universal testing, i.e., an approach in which we screen the entire population, can be utilized to mitigate this epidemic. To this end, we rely on PCR test pooling of individuals that belong to the same households, to allow for a universal testing procedure that is feasible with the limited testing capacity. We evaluate two isolation strategies: on the one hand pool isolation, where we isolate all individuals that belong to a positive PCR test pool, and on the other hand individual isolation, where we determine which of the individuals that belong to the positive PCR pool are positive, through an additional testing step. We evaluate this universal testing approach in the STRIDE individual-based epidemiological model in the context of the Belgian COVID-19 epidemic. As the organisation of universal testing will be challenging, we discuss the different aspects related to sample extraction and PCR testing, to demonstrate the feasibility of universal testing when a decentralized testing approach is used. We show through simulation, that weekly universal testing is able to control the epidemic, even when many of the contact reductions are relieved. Finally, our model shows that the use of universal testing in combination with stringent contact reductions could be considered as a strategy to eradicate the virus.


Assuntos
/métodos , /prevenção & controle , Epidemias/prevenção & controle , Bélgica/epidemiologia , /estatística & dados numéricos , Biologia Computacional , Simulação por Computador , Busca de Comunicante/métodos , Busca de Comunicante/estatística & dados numéricos , Busca de Comunicante/tendências , Reações Falso-Negativas , Características da Família , Estudos de Viabilidade , Humanos , Programas de Rastreamento/métodos , Programas de Rastreamento/estatística & dados numéricos , Programas de Rastreamento/tendências , Modelos Estatísticos , Quarentena/métodos , Quarentena/estatística & dados numéricos , Quarentena/tendências , Viagem
10.
Emerg Infect Dis ; 27(4)2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33600301

RESUMO

We determined secondary attack rates (SAR) among close contacts of 59 asymptomatic and symptomatic coronavirus disease case-patients by presymptomatic and symptomatic exposure. We observed no transmission from asymptomatic case-patients and highest SAR through presymptomatic exposure. Rapid quarantine of close contacts with or without symptoms is needed to prevent presymptomatic transmission.


Assuntos
Busca de Comunicante , Transmissão de Doença Infecciosa , Quarentena , /isolamento & purificação , Adulto , Doenças Assintomáticas/epidemiologia , /epidemiologia , /transmissão , Busca de Comunicante/métodos , Busca de Comunicante/estatística & dados numéricos , Transmissão de Doença Infecciosa/prevenção & controle , Transmissão de Doença Infecciosa/estatística & dados numéricos , Feminino , Alemanha/epidemiologia , Humanos , Incidência , Masculino , Quarentena/métodos , Quarentena/organização & administração , Risco Ajustado , Avaliação de Sintomas/métodos , Avaliação de Sintomas/estatística & dados numéricos
11.
Public Health ; 192: 30-32, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33611168

RESUMO

OBJECTIVES: SARS-CoV-2 is a highly contagious virus that causes coronavirus disease 2019 (COVID-19) and can affect people of any age with potential for serious symptoms. Since the start of the COVID-19 pandemic, global infection rates have been on the rise with world leaders looking to slow and stop viral transmission. This study is looking at suburban cohabitation/familial infection to compare to similar studies from other countries. STUDY DESIGN: A retrospective review of medical records was collected using the Connecticut Electronic Disease Surveillance System. METHODS: A total of 406 cases who tested positive for SARS-COV-2 from February to June 2020 were reviewed from three towns located in Connecticut, USA. Cohabitation infection rates were identified using the home addresses of those with confirmed SARS-CoV-2 test results, with the first documented case being the index case, and additional home members being the secondary cases. RESULTS: Secondary transmission of SARS-CoV-2 developed in 126 of 406 household contacts (31%). Linear regression indicated positive relationship between cohabitation and age. CONCLUSIONS: The cohabitation infection attack rate of SARS-CoV-2 is significantly higher than previously reported. Age of household contacts and spousal relationship to the index case are risk factors for transmission of SARS-CoV-2 within a household.


Assuntos
/transmissão , Características da Família , Vigilância em Saúde Pública/métodos , /isolamento & purificação , Adulto , Infecções Comunitárias Adquiridas/transmissão , Busca de Comunicante/estatística & dados numéricos , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Pandemias , Estudos Retrospectivos , Fatores de Risco , Estados Unidos/epidemiologia
12.
Medicine (Baltimore) ; 100(5): e23925, 2021 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-33592845

RESUMO

ABSTRACT: The World Health Organization (WHO) classified the spread of COVID-19 (Coronavirus Disease 2019) as a global pandemic in March. Scholars predict that the pandemic will continue into the coming winter and will become a seasonal epidemic in the following year. Therefore, the identification of effective control measures becomes extremely important. Although many reports have been published since the COVID-19 outbreak, no studies have identified the relative effectiveness of a combination of control measures implemented in Wuhan and other areas in China. To this end, a retrospective analysis by the collection and modeling of an unprecedented number of epidemiology records in China of the early stage of the outbreaks can be valuable.In this study, we developed a new dynamic model to describe the spread of COVID-19 and to quantify the effectiveness of control measures. The transmission rate, daily close contacts, and the average time from onset to isolation were identified as crucial factors in viral spreading. Moreover, the capacity of a local health-care system is identified as a threshold to control an outbreak in its early stage. We took these factors as controlling parameters in our model. The parameters are estimated based on epidemiological reports from national and local Center for Disease Control (CDCs).A retrospective simulation showed the effectiveness of combinations of 4 major control measures implemented in Wuhan: hospital isolation, social distancing, self-protection by wearing masks, and extensive medical testing. Further analysis indicated critical intervention conditions and times required to control an outbreak in the early stage. Our simulations showed that South Korea has kept the spread of COVID-19 at a low level through extensive medical testing. Furthermore, a predictive simulation for Italy indicated that Italy would contain the outbreak in late May under strict social distancing.In our general analysis, no single measure could contain a COVID-19 outbreak once a health-care system is overloaded. Extensive medical testing could keep viral spreading at a low level. Wearing masks functions as favorably as social distancing but with much lower socioeconomic costs.


Assuntos
Controle de Doenças Transmissíveis , Hospitalização/estatística & dados numéricos , Avaliação de Resultados em Cuidados de Saúde/métodos , /isolamento & purificação , /economia , /prevenção & controle , China/epidemiologia , Controle de Doenças Transmissíveis/métodos , Controle de Doenças Transmissíveis/organização & administração , Controle de Doenças Transmissíveis/normas , Busca de Comunicante/estatística & dados numéricos , Transmissão de Doença Infecciosa/prevenção & controle , Transmissão de Doença Infecciosa/estatística & dados numéricos , Humanos , Modelos Teóricos , Mortalidade , Análise de Sistemas , Tempo para o Tratamento/estatística & dados numéricos
13.
Sci Rep ; 11(1): 4243, 2021 02 19.
Artigo em Inglês | MEDLINE | ID: mdl-33608566

RESUMO

SARS-CoV-2 infection ranges from asymptomatic to severe with lingering symptomatology in some. This prompted investigation of whether or not asymptomatic disease results in measurable immune activation post-infection. Immune activation following asymptomatic SARS-CoV-2 infection was characterized through a comparative investigation of the immune cell transcriptomes from 43 asymptomatic seropositive and 52 highly exposed seronegative individuals from the same community 4-6 weeks following a superspreading event. Few of the 95 individuals had underlying health issues. One seropositive individual reported Cystic Fibrosis and one individual reported Incontinentia pigmenti. No evidence of immune activation was found in asymptomatic seropositive individuals with the exception of the Cystic Fibrosis patient. There were no statistically significant differences in immune transcriptomes between asymptomatic seropositive and highly exposed seronegative individuals. Four positive controls, mildly symptomatic seropositive individuals whose blood was examined 3 weeks following infection, showed immune activation. Negative controls were four seronegative individuals from neighboring communities without COVID-19. All individuals remained in their usual state of health through a five-month follow-up after sample collection. In summary, whole blood transcriptomes identified individual immune profiles within a community population and showed that asymptomatic infection within a super-spreading event was not associated with enduring immunological activation.


Assuntos
/imunologia , Transcriptoma/imunologia , Imunidade Adaptativa/genética , Adolescente , Adulto , Idoso , Anticorpos Antivirais/sangue , Anticorpos Antivirais/isolamento & purificação , Infecções Assintomáticas , Áustria , /diagnóstico , /estatística & dados numéricos , Criança , Pré-Escolar , Busca de Comunicante/estatística & dados numéricos , Características da Família , Feminino , Seguimentos , Interações entre Hospedeiro e Microrganismos/genética , Interações entre Hospedeiro e Microrganismos/imunologia , Humanos , Imunidade Inata/genética , Lactente , Masculino , Pessoa de Meia-Idade , RNA-Seq/estatística & dados numéricos , Adulto Jovem
14.
Mo Med ; 118(1): 81-84, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33551491

RESUMO

The public health community has used contact tracing to address pandemics since the eighteenth century. With the emergence of COVID-19, these classical skills are the primary defense for communities to limit morbidity and mortality during the pandemic. Here we describe the methods, strengths, and challenges of contact tracing.


Assuntos
/prevenção & controle , Busca de Comunicante/métodos , Pandemias/prevenção & controle , Conscientização , /epidemiologia , Busca de Comunicante/estatística & dados numéricos , Surtos de Doenças/prevenção & controle , Desinfecção das Mãos/métodos , Humanos , Missouri/epidemiologia , Isolamento de Pacientes/métodos , Saúde Pública/métodos , Saúde Pública/normas , Quarentena/métodos , /isolamento & purificação
15.
Emerg Infect Dis ; 27(3): 915-918, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33622475

RESUMO

The overall coronavirus disease secondary attack rate (SAR) in family members was 19.0% in 10 prefectures of Japan during February 22-May 31, 2020. The SAR was lower for primary cases diagnosed early, within 2 days after symptom onset. The SAR of asymptomatic primary cases was 11.8%.


Assuntos
/epidemiologia , Família , Infecções Assintomáticas/epidemiologia , /transmissão , Busca de Comunicante/estatística & dados numéricos , Feminino , Humanos , Incidência , Japão/epidemiologia , Masculino , Fatores de Tempo
16.
J Med Internet Res ; 23(2): e24730, 2021 02 03.
Artigo em Inglês | MEDLINE | ID: mdl-33465034

RESUMO

BACKGROUND: During the COVID-19 pandemic, new digital solutions have been developed for infection control. In particular, contact tracing mobile apps provide a means for governments to manage both health and economic concerns. However, public reception of these apps is paramount to their success, and global uptake rates have been low. OBJECTIVE: In this study, we sought to identify the characteristics of individuals or factors potentially associated with voluntary downloads of a contact tracing mobile app in Singapore. METHODS: A cohort of 505 adults from the general community completed an online survey. As the primary outcome measure, participants were asked to indicate whether they had downloaded the contact tracing app TraceTogether introduced at the national level. The following were assessed as predictor variables: (1) participant demographics, (2) behavioral modifications on account of the pandemic, and (3) pandemic severity (the number of cases and lockdown status). RESULTS: Within our data set, the strongest predictor of the uptake of TraceTogether was the extent to which individuals had already adjusted their lifestyles because of the pandemic (z=13.56; P<.001). Network analyses revealed that uptake was most related to the following: using hand sanitizers, avoiding public transport, and preferring outdoor over indoor venues during the pandemic. However, demographic and situational characteristics were not significantly associated with app downloads. CONCLUSIONS: Efforts to introduce contact tracing apps could capitalize on pandemic-related behavioral adjustments among individuals. Given that a large number of individuals is required to download contact tracing apps for contact tracing to be effective, further studies are required to understand how citizens respond to contact tracing apps. TRIAL REGISTRATION: ClinicalTrials.gov NCT04468581, https://clinicaltrials.gov/ct2/show/NCT04468581.


Assuntos
/prevenção & controle , Busca de Comunicante/estatística & dados numéricos , Comportamentos Relacionados com a Saúde , Aplicativos Móveis/estatística & dados numéricos , Adulto , Estudos de Coortes , Controle de Doenças Transmissíveis/estatística & dados numéricos , Busca de Comunicante/métodos , Feminino , Desinfecção das Mãos , Higienizadores de Mão/uso terapêutico , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Pandemias , Singapura , Inquéritos e Questionários , Transportes/estatística & dados numéricos
17.
Sci Rep ; 11(1): 2145, 2021 01 25.
Artigo em Inglês | MEDLINE | ID: mdl-33495491

RESUMO

The coronavirus disease (COVID-19) outbreak has killed over a million people since its emergence in late 2019. However, there has been substantial variability in the policies and intensity of diagnostic efforts between countries. In this paper, we quantitatively evaluate the association between national contact tracing policies and case fatality rates of COVID-19 in 138 countries. Our regression analyses indicate that countries that implement comprehensive contact tracing have significantly lower case fatality rates. This association of contact tracing policy and case fatality rates is robust in our longitudinal regression models, even after controlling for the number of tests conducted and non-pharmaceutical control measures adopted by governments. Our results suggest that comprehensive contact tracing is instrumental not only to curtailing transmission but also to reducing case fatality rates. Contact tracing achieves the early detection and isolation of secondary cases which are particularly important given that the peak in infectiousness occurs during the presymptomatic phase. The early detection achieved by contact tracing accelerates the rate at which infected individuals receive medical care they need to maximize their chance of recovery. In addition, the combination of reduced transmission and more rapid recovery diminishes the burden on the healthcare system which in turn ensures that the resources remain available for individuals who do become infected.


Assuntos
/mortalidade , Busca de Comunicante/estatística & dados numéricos , Saúde Global/estatística & dados numéricos , Pandemias/prevenção & controle , Política Pública , /diagnóstico , /virologia , Humanos , Pandemias/estatística & dados numéricos , /patogenicidade
18.
Nat Commun ; 12(1): 587, 2021 01 26.
Artigo em Inglês | MEDLINE | ID: mdl-33500407

RESUMO

While Digital contact tracing (DCT) has been argued to be a valuable complement to manual tracing in the containment of COVID-19, no empirical evidence of its effectiveness is available to date. Here, we report the results of a 4-week population-based controlled experiment that took place in La Gomera (Canary Islands, Spain) between June and July 2020, where we assessed the epidemiological impact of the Spanish DCT app Radar Covid. After a substantial communication campaign, we estimate that at least 33% of the population adopted the technology and further showed relatively high adherence and compliance as well as a quick turnaround time. The app detects about 6.3 close-contacts per primary simulated infection, a significant percentage being contacts with strangers, although the spontaneous follow-up rate of these notified cases is low. Overall, these results provide experimental evidence of the potential usefulness of DCT during an epidemic outbreak in a real population.


Assuntos
/epidemiologia , Busca de Comunicante/métodos , Aplicativos Móveis/estatística & dados numéricos , Pandemias/prevenção & controle , Cooperação do Paciente/estatística & dados numéricos , Adolescente , Adulto , Distribuição por Idade , /transmissão , Busca de Comunicante/estatística & dados numéricos , Feminino , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Privacidade , Smartphone , Espanha/epidemiologia , Inquéritos e Questionários/estatística & dados numéricos , Adulto Jovem
19.
Public Health ; 190: 147-151, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33386140

RESUMO

OBJECTIVES: The objective of this study was to inform public health practitioners who are designing, adapting and implementing testing and tracing strategies for Coronavirus disease (COVID-19) control. STUDY DESIGN: The study design is monitoring and evaluation of a national public health protection programme. METHODS: All close contacts of laboratory-confirmed cases of COVID-19 identified between the 19th May and 2nd August were included; secondary attack rates and numbers needed to test were estimated. RESULTS: Four thousand five hundred eighty six of 7272 (63%) close contacts of cases were tested with at least one test. The secondary attack rate in close contacts who were tested was 7% (95% Confidence Interval [CI]: 6.3 - 7.8%). At the 'day 0' test, 14.6% (95% CI: 11.6-17.6%) of symptomatic close contacts tested positive compared with 5.2% (95% CI: 4.4-5.9%) of asymptomatic close contacts. CONCLUSIONS: The application of additional symptom-based criteria for testing in this high-incidence population (close contacts) is of limited utility because of the low negative predictive value of absence of symptoms.


Assuntos
/estatística & dados numéricos , Busca de Comunicante/estatística & dados numéricos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Infecções Assintomáticas , Portador Sadio , Criança , Pré-Escolar , Busca de Comunicante/métodos , Feminino , Humanos , Incidência , Lactente , Recém-Nascido , Irlanda/epidemiologia , Masculino , Pessoa de Meia-Idade
20.
Public Health Rep ; 136(1): 88-96, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33108976

RESUMO

OBJECTIVES: Widespread global transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus causing coronavirus disease 2019 (COVID-19), continues. Many questions remain about asymptomatic or atypical infections and transmission dynamics. We used comprehensive contact tracing of the first 2 confirmed patients in Illinois with COVID-19 and serologic SARS-CoV-2 antibody testing to determine whether contacts had evidence of undetected COVID-19. METHODS: Contacts were eligible for serologic follow-up if previously tested for COVID-19 during an initial investigation or had greater-risk exposures. Contacts completed a standardized questionnaire during the initial investigation. We classified exposure risk as high, medium, or low based on interactions with 2 index patients and use of personal protective equipment (PPE). Serologic testing used a SARS-CoV-2 spike enzyme-linked immunosorbent assay on serum specimens collected from participants approximately 6 weeks after initial exposure to either index patient. The 2 index patients provided serum specimens throughout their illness. We collected data on demographic, exposure, and epidemiologic characteristics. RESULTS: Of 347 contacts, 110 were eligible for serologic follow-up; 59 (17% of all contacts) enrolled. Of these, 53 (90%) were health care personnel and 6 (10%) were community contacts. Seventeen (29%) reported high-risk exposures, 15 (25%) medium-risk, and 27 (46%) low-risk. No participant had evidence of SARS-CoV-2 antibodies. The 2 index patients had antibodies detected at dilutions >1:6400 within 4 weeks after symptom onset. CONCLUSIONS: In serologic follow-up of the first 2 known patients in Illinois with COVID-19, we found no secondary transmission among tested contacts. Lack of seroconversion among these contacts adds to our understanding of conditions (ie, use of PPE) under which SARS-CoV-2 infections might not result in transmission and demonstrates that SARS-CoV-2 antibody testing is a useful tool to verify epidemiologic findings.


Assuntos
/epidemiologia , Busca de Comunicante/estatística & dados numéricos , Pessoal de Saúde/estatística & dados numéricos , Exposição Ocupacional/estatística & dados numéricos , /imunologia , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Illinois/epidemiologia , Masculino , Pandemias , Equipamento de Proteção Individual , Medição de Risco
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