scholarly journals Empirical evidence on the efficiency of bidirectional contact tracing in COVID-19

2021 ◽  
Author(s):  
Joren Raymenants ◽  
Caspar Geenen ◽  
Nelissen ◽  
Sarah Gorissen ◽  
Emmanuel André
Keyword(s):  
Cohort Study ◽  
Symptom Onset ◽  
Contact Tracing ◽  
Control Group ◽  
Infected Person ◽  
Risk Of Infection ◽  
Modelling Studies ◽  
Large Cohort Study ◽  
Community Transmission ◽  
Standard Contact

Abstract Despite ubiquitous rollout of contact tracing to counteract the spread of COVID-19, few countries have been spared from widespread community transmission, highlighting the need for more effective tracing strategies1,2. Standard contact tracing practice identifies, quarantines and tests persons exposed to an infected person during the contagious period, assumed to start two days before symptom onset or diagnosis3,4. Backward contact tracing intends to identify the source of the infection and persons infected by the same source, either by extending the contact tracing window or investigating suspected source events. These approaches have shown promise in modelling studies, but lack empirical data supporting their efficiency5–7. In the first large cohort study on backward contact tracing for COVID-19, we found that extending the contact tracing window backward by 5 days increased the number of identified contacts by 49.2%. The risk of infection amongst these additional contacts was similar to contacts exposed during the standard tracing window and significantly higher than symptomatic individuals in a control group, leading to an increase of 42.0% in cases identified through contact tracing. The risk was not limited to attendees of suspected source events. Our results imply an urgent need to implement backward contact tracing globally.

scholarly journals Estimating the generation interval for COVID-19 based on symptom onset data

2020 ◽  
Author(s):  
Ganyani Tapiwa ◽  
Kremer Cécile ◽  
Chen Dongxuan ◽  
Torneri Andrea ◽  
Faes Christel ◽  
...  
Keyword(s):  
Incubation Period ◽  
Symptom Onset ◽  
Contact Tracing ◽  
Transmission Network ◽  
Generation Interval ◽  
Period Distribution ◽  
Reproduction Numbers ◽  
Serial Interval ◽  
Modelling Studies ◽  
Interval Distribution

AbstractBackgroundEstimating key infectious disease parameters from the COVID-19 outbreak is quintessential for modelling studies and guiding intervention strategies. Whereas different estimates for the incubation period distribution and the serial interval distribution have been reported, estimates of the generation interval for COVID-19 have not been provided.MethodsWe used outbreak data from clusters in Singapore and Tianjin, China to estimate the generation interval from symptom onset data while acknowledging uncertainty about the incubation period distribution and the underlying transmission network. From those estimates we obtained the proportions pre-symptomatic transmission and reproduction numbers.ResultsThe mean generation interval was 5.20 (95%CI 3.78-6.78) days for Singapore and 3.95 (95%CI 3.01-4.91) days for Tianjin, China when relying on a previously reported incubation period with mean 5.2 and SD 2.8 days. The proportion of pre-symptomatic transmission was 48% (95%CI 32-67%) for Singapore and 62% (95%CI 50-76%) for Tianjin, China. Estimates of the reproduction number based on the generation interval distribution were slightly higher than those based on the serial interval distribution.ConclusionsEstimating generation and serial interval distributions from outbreak data requires careful investigation of the underlying transmission network. Detailed contact tracing information is essential for correctly estimating these quantities.

scholarly journals Effectiveness of interventions targeting air travellers for delaying local outbreaks of SARS-CoV-2

2020 ◽  
Vol 27 (5) ◽  
Author(s):  
Samuel Clifford ◽  
Carl A B Pearson ◽  
Petra Klepac ◽  
Kevin Van Zandvoort ◽  
Billy J Quilty ◽  
...  
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Symptom Onset ◽  
Additional Benefit ◽  
Stochastic Simulations ◽  
Sensitivity Analyses ◽  
Contact Tracing ◽  
Secondary Infections ◽  
Community Transmission

Abstract Background We evaluated if interventions aimed at air travellers can delay local severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) community transmission in a previously unaffected country. Methods We simulated infected air travellers arriving into countries with no sustained SARS-CoV-2 transmission or other introduction routes from affected regions. We assessed the effectiveness of syndromic screening at departure and/or arrival and traveller sensitisation to the COVID-2019-like symptoms with the aim to trigger rapid self-isolation and reporting on symptom onset to enable contact tracing. We assumed that syndromic screening would reduce the number of infected arrivals and that traveller sensitisation reduces the average number of secondary cases. We use stochastic simulations to account for uncertainty in both arrival and secondary infections rates, and present sensitivity analyses on arrival rates of infected travellers and the effectiveness of traveller sensitisation. We report the median expected delay achievable in each scenario and an inner 50% interval. Results Under baseline assumptions, introducing exit and entry screening in combination with traveller sensitisation can delay a local SARS-CoV-2 outbreak by 8 days (50% interval: 3–14 days) when the rate of importation is 1 infected traveller per week at time of introduction. The additional benefit of entry screening is small if exit screening is effective: the combination of only exit screening and traveller sensitisation can delay an outbreak by 7 days (50% interval: 2–13 days). In the absence of screening, with less effective sensitisation, or a higher rate of importation, these delays shrink rapidly to <4 days. Conclusion Syndromic screening and traveller sensitisation in combination may have marginally delayed SARS-CoV-2 outbreaks in unaffected countries.

scholarly journals Effectiveness of interventions targeting air travellers for delaying local outbreaks of SARS-CoV-2

2020 ◽  
Author(s):  
Samuel Clifford ◽  
Carl A.B. Pearson ◽  
Petra Klepac ◽  
Kevin Van Zandvoort ◽  
Billy J. Quilty ◽  
...  
Keyword(s):  
Symptom Onset ◽  
Additional Benefit ◽  
Stochastic Simulations ◽  
Sensitivity Analyses ◽  
Contact Tracing ◽  
Secondary Infections ◽  
Community Transmission

AbstractBackgroundWe evaluated if interventions aimed at air travellers can delay local SARS-CoV-2 community transmission in a previously unaffected country.MethodsWe simulated infected air travellers arriving into countries with no sustained SARS-CoV-2 transmission or other introduction routes from affected regions. We assessed the effectiveness of syndromic screening at departure and/or arrival & traveller sensitisation to the COVID-2019-like symptoms with the aim to trigger rapid self-isolation and reporting on symptom onset to enable contact tracing. We assumed that syndromic screening would reduce the number of infected arrivals and that traveller sensitisation reduces the average number of secondary cases. We use stochastic simulations to account for uncertainty in both arrival and secondary infections rates, and present sensitivity analyses on arrival rates of infected travellers and the effectiveness of traveller sensitisation. We report the median expected delay achievable in each scenario and an inner 50% interval.ResultsUnder baseline assumptions, introducing exit and entry screening in combination with traveller sensitisation can delay a local SARS-CoV-2 outbreak by 8 days (50% interval: 3-14 days) when the rate of importation is 1 infected traveller per week at time of introduction. The additional benefit of entry screening is small if exit screening is effective: the combination of only exit screening and traveller sensitisation can delay an outbreak by 7 days (50% interval: 2-13 days). In the absence of screening, with less effective sensitisation, or a higher rate of importation, these delays shrink rapidly to less than 4 days.ConclusionSyndromic screening and traveller sensitisation in combination may have marginally delayed SARS-CoV-2 outbreaks in unaffected countries.

scholarly journals Designing Efficient Contact Tracing Through Risk-Based Quarantining

2020 ◽  
Author(s):  
Andrew Perrault ◽  
Marie Charpignon ◽  
Jonathan Gruber ◽  
Milind Tambe ◽  
Maimuna S. Majumder
Keyword(s):  
High Risk ◽  
Contact Tracing ◽  
Common Source ◽  
Risk Of Infection ◽  
Comparable Level ◽  
Small Risk ◽  
Transmission Reduction ◽  
Time Served ◽  
Cluster A ◽  
Standard Contact

AbstractContact tracing for COVID-19 is especially challenging because transmission often occurs in the absence of symptoms and because a purported 20% of cases cause 80% of infections, resulting in a small risk of infection for some contacts and a high risk for others. Here, we introduce risk-based quarantine, a system for contact tracing where each cluster (a group of individuals with a common source of exposure) is observed for symptoms when tracing begins, and clusters that do not display them are released from quarantine. We show that, under our assumptions, risk-based quarantine reduces the amount of quarantine time served by more than 30%, while achieving a reduction in transmission similar to standard contact tracing policies where all contacts are quarantined for two weeks. We compare our proposed risk-based quarantine approach against test-driven release policies, which fail to achieve a comparable level of transmission reduction due to the inability of tests to detect exposed people who are not yet infectious but will eventually become so. Additionally, test-based release policies are expensive, limiting their effectiveness in low-resource environments, whereas the costs imposed by risk-based quarantine are primarily in terms of labor and organization.

scholarly journals Psychological Traits and Behavioural Influences in Patients with Dystonia—An Observational Cohort Study in a Romanian Neurology Department

Life ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 612
Author(s):  
Eugenia Irene Davidescu ◽  
Irina Odajiu ◽  
Delia Tulbă ◽  
Iulia Mitrea ◽  
Camelia Cucu ◽  
...  
Keyword(s):  
Cohort Study ◽  
Informed Consent ◽  
Personality Traits ◽  
Patient Group ◽  
Observational Cohort Study ◽  
Control Group ◽  
Inclusion Criteria ◽  
Control Subjects ◽  
Observational Cohort ◽  
Idiopathic Dystonia

(1) Background: Emerging evidence indicates that non-motor symptoms significantly influence the quality of life in dystonic patients. Therefore, it is essential to evaluate their psychological characteristics and personality traits. (2) Methods: Subjects with idiopathic dystonia and a matched control group were enrolled in this prospective observational cohort study. Inclusion criteria for patient group included idiopathic dystonia diagnosis, evolution exceeding 1 year, and signed informed consent. Inclusion criteria for the control group included lack of neurological comorbidities and signed informed consent. All subjects completed the DECAS Personality Inventory along with an additional form of demographic factors. Data (including descriptive statistics and univariate and multivariate analysis) were analyzed with SPSS. (3) Results: In total, 95 participants were included, of which 57 were in the patient group. Females prevailed (80%), and the mean age was 54.64 ± 12.8 years. The most frequent clinical features of dystonia were focal distribution (71.9%) and progressive disease course (94.73%). The patients underwent regular treatment with botulinum toxin (85.95%). In addition, patients with dystonia obtained significantly higher openness scores than controls, even after adjusting for possible confounders (p = 0.006). Personality traits were also different between the two groups, with patients more often being fantasists (p = 0.007), experimenters (p = 0.022), sophists (p = 0.040), seldom acceptors (p = 0.022), and pragmatics (p = 0.022) than control subjects. (4) Conclusion: Dystonic patients tend to have different personality profiles compared to control subjects, which should be taken into consideration by the treating neurologist.

Midfoot Function Before and After Total Ankle Arthroplasty

2021 ◽  
pp. 107110072199578
Author(s):  
Frank E. DiLiberto ◽  
Steven L. Haddad ◽  
Steven A. Miller ◽  
Anand M. Vora
Keyword(s):  
Cohort Study ◽  
Prospective Cohort Study ◽  
Prospective Cohort ◽  
Peak Power ◽  
Nonparametric Tests ◽  
Total Ankle Arthroplasty ◽  
Control Group ◽  
Ankle Arthroplasty ◽  
First Metatarsal ◽  
Before And After

Background: Information regarding the effect of total ankle arthroplasty (TAA) on midfoot function is extremely limited. The purpose of this study was to characterize midfoot region motion and power during walking in people before and after TAA. Methods: This was a prospective cohort study of 19 patients with end-stage ankle arthritis who received a TAA and 19 healthy control group participants. A motion capture and force plate system was used to record sagittal and transverse plane first metatarsal and lateral forefoot with respect to hindfoot motion, as well as sagittal plane midfoot region positive and negative peak power during walking. Parametric or nonparametric tests to examine differences and equivalence across time were conducted. Comparisons to examine differences between postoperative TAA group and control group foot function were also performed. Results: Involved-limb midfoot function was not different between the preoperative and 6-month postoperative time point in the TAA group (all P ≥ .17). Equivalence testing revealed similarity in all midfoot function variables across time (all P < .05). Decreased first metatarsal and lateral forefoot motion, as well as positive peak power generation, were noted in the TAA group postoperative involved limb in comparison to the control group (all P ≤ .01). Conclusion: The similarity of midfoot function across time, along with differences in midfoot function in comparison to controls, suggests that TAA does not change midfoot deficits by 6 months postoperation. Level of Evidence: Level II, prospective cohort study.

scholarly journals Impact of The Daily Mile on children’s physical and mental health, and educational attainment in primary schools: iMprOVE cohort study protocol

BMJ Open ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. e045879
Author(s):  
Bina Ram ◽  
Anna Chalkley ◽  
Esther van Sluijs ◽  
Rachel Phillips ◽  
Tishya Venkatraman ◽  
...  
Keyword(s):  
Mental Health ◽  
Physical Activity ◽  
Cohort Study ◽  
Educational Attainment ◽  
Primary School ◽  
Primary Schools ◽  
Intervention Group ◽  
Control Group ◽  
Physical And Mental Health ◽  
School Year

IntroductionSchool-based active mile initiatives such as The Daily Mile (TDM) are widely promoted to address shortfalls in meeting physical activity recommendations. The iMprOVE Study aims to examine the impact of TDM on children’s physical and mental health and educational attainment throughout primary school.Methods and analysisiMprOVE is a longitudinal quasi-experimental cohort study. We will send a survey to all state-funded primary schools in Greater London to identify participation in TDM. The survey responses will be used for non-random allocation to either the intervention group (Daily Mile schools) or to the control group (non-Daily Mile schools). We aim to recruit 3533 year 1 children (aged 5–6 years) from 77 primary schools and follow them up annually until the end of their primary school years. Data collection taking place at baseline (children in school year 1) and each primary school year thereafter includes device-based measures of moderate-to-vigorous physical activity (MVPA) and questionnaires to measure mental health (Strengths and Difficulties Questionnaire) and educational attainment (ratings from ‘below expected’ to ‘above expected levels’). The primary outcome is the mean change in MVPA minutes from baseline to year 6 during the school day among the intervention group compared with controls. We will use multilevel linear regression models adjusting for sociodemographic data and participation in TDM. The study is powered to detect a 10% (5.5 min) difference between the intervention and control group which would be considered clinically significant.Ethics and disseminationEthics has been approved from Imperial College Research Ethics Committee, reference 20IC6127. Key findings will be disseminated to the public through research networks, social, print and media broadcasts, community engagement opportunities and schools. We will work with policy-makers for direct application and impact of our findings.

scholarly journals Detection of Salivary miRNAs That Predict Chronic Periodontitis Progression: A Cohort Study

2021 ◽  
Vol 18 (15) ◽  
pp. 8010
Author(s):  
Kohei Fujimori ◽  
Toshiki Yoneda ◽  
Takaaki Tomofuji ◽  
Daisuke Ekuni ◽  
Tetsuji Azuma ◽  
...  
Keyword(s):  
Cohort Study ◽  
Chronic Periodontitis ◽  
Characteristic Curve ◽  
Control Group ◽  
Discrimination Power ◽  
Whole Saliva ◽  
Supportive Periodontal Therapy ◽  
New Biomarkers ◽  
Unstimulated Whole Saliva ◽  
Attachment Level

The aim of this two-year cohort study was to investigate salivary microRNAs (miRNAs) that predict periodontitis progression. A total of 120 patients who underwent supportive periodontal therapy were recruited. Unstimulated whole saliva was collected at baseline. Two years later, 44 patients were followed up (median age, 67.1 years) and divided into two groups: progression group (n = 22), with one or more sites with clinical attachment level (CAL) progression (>3 mm compared with baseline) or tooth extraction due to periodontitis progression; and the control group (n = 22), which did not exhibit CAL progression. In the microarray analysis of salivary miRNAs, hsa-miR-5571-5p, hsa-miR-17-3p, hsa-let-7f-5p, hsa-miR-4724-3p, hsa-miR-99a-5p, hsa-miR-200a-3p, hsa-miR-28-5p, hsa-miR-320d, and hsa-miR-31-5p showed fold change values <0.5 or ≥2.0 in the progression group compared with the control group (p < 0.05). On receiver operating characteristic curve analysis, areas under the curves of hsa-miR-5571-5p, hsa-let-7f-5p, hsa-miR-99a-5p, hsa-miR-28-5p, and hsa-miR-320d were >0.7, indicating fair discrimination power. The expressions of salivary hsa-miR-5571-5p, hsa-let-7f-5p, hsa-miR-99a-5p, hsa-miR-28-5p, and hsa-miR-320d were associated with periodontitis progression in patients with chronic periodontitis. These salivary miRNAs may be new biomarkers for progression of periodontitis, and monitoring them may contribute to new diagnostics and precision medicine for periodontitis.

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