Designing Efficient Contact Tracing Through Risk-Based Quarantining

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.

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

10.21203/rs.3.rs-952839/v1 ◽

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.

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Ensuring safety and availability of healthcare workers in the era of COVID-19: An experience from the Eastern State of India

Indian Journal of Medical Sciences ◽

10.25259/ijms_128_2020 ◽

2020 ◽

Vol 72 ◽

pp. 58-64 ◽

Cited By ~ 1

Author(s):

Neeraj Agarwal ◽

Bijit Biswas ◽

Rathish Nair

Keyword(s):

High Risk ◽

Healthcare Workers ◽

Health Workers ◽

Low Risk ◽

Contact Tracing ◽

Risk Exposure ◽

Risk Of Infection ◽

Healthcare Settings ◽

Contact Investigation ◽

Tracing Algorithm

Objectives: The objective of this study was to design a contact tracing algorithm and contact investigation form for healthcare workers deployed in rendering essential health-care services in limitedly resourced healthcare settings during the COVID era. Material and Methods: It was an observational study, longitudinal in design. Based on the existing evidence as of April 15, 2020, we have designed a contact tracing algorithm and contact investigation form to determine the risk of infection among healthcare workers. Later, we have tested the developed contact tracing algorithm and contact investigation from among 28 suspected contacts of a confirmed COVID-19 case admitted in all India Institute of Medical Sciences Patna, Bihar, India. Results: Using the designed contact investigation form, all the 28 suspected contacts of the confirmed COVID-19 case were interviewed, among which only 7(25%) were found to be having high-risk exposure. All persons with high-risk exposure were home quarantined for 5 days, along with their direct contacts. Eventually, all high-risk contacts were tested negative on the 5th day after exposure and immediately joined their duties after that. Those who were at low risk of infection continued to work and self-monitor for COVID compatible symptoms for 14 days. Eventually, none of the low-risk exposure persons developed COVID compatible symptoms, therefore deferred testing. Conclusion: The contact tracing approach designed in the current study is a balanced one where we tried to balance health workers safety without compromising their availability for duty. This approach can also be implemented in other healthcare settings in the era of COVID-19.

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Investigation of Four Clusters of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in Rwanda, 2020

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18137018 ◽

2021 ◽

Vol 18 (13) ◽

pp. 7018

Author(s):

Olivier Nsekuye ◽

Edson Rwagasore ◽

Marie Aime Muhimpundu ◽

Ziad El-Khatib ◽

Daniel Ntabanganyimana ◽

...

Keyword(s):

High Risk ◽

Severe Acute Respiratory Syndrome ◽

Symptom Onset ◽

Attack Rate ◽

Positive Sample ◽

Contact Tracing ◽

Face To Face ◽

Laboratory Confirmation ◽

Closed Environment ◽

Index Cases

We reported the findings of the first Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) four clusters identified in Rwanda. Case-investigations included contact elicitation, testing, and isolation/quarantine of confirmed cases. Socio-demographic and clinical data on cases and contacts were collected. A confirmed case was a person with laboratory confirmation of SARS-CoV-2 infection (PCR) while a contact was any person who had contact with a SARS-CoV-2 confirmed case within 72 h prior, to 14 days after symptom onset; or 14 days before collection of the laboratory-positive sample for asymptomatic cases. High risk contacts were those who had come into unprotected face-to-face contact or had been in a closed environment with a SARS-CoV-2 case for >15 min. Forty cases were reported from four clusters by 22 April 2020, accounting for 61% of locally transmitted cases within six weeks. Clusters A, B, C and D were associated with two nightclubs, one house party, and different families or households living in the same compound (multi-family dwelling). Thirty-six of the 1035 contacts tested were positive (secondary attack rate: 3.5%). Positivity rates were highest among the high-risk contacts compared to low-risk contacts (10% vs. 2.2%). Index cases in three of the clusters were imported through international travelling. Fifteen of the 40 cases (38%) were asymptomatic while 13/25 (52%) and 8/25 (32%) of symptomatic cases had a cough and fever respectively. Gatherings in closed spaces were the main early drivers of transmission. Systematic case-investigations contact tracing and testing likely contributed to the early containment of SARS-CoV-2 in Rwanda.

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Will Gay and Bisexually Active Men at High Risk of Infection Use Over-the-Counter Rapid HIV Tests to Screen Sexual Partners?

The Journal of Sex Research ◽

10.1080/00224499.2011.647117 ◽

2012 ◽

Vol 49 (4) ◽

pp. 379-387 ◽

Cited By ~ 70

Author(s):

Alex Carballo-Diéguez ◽

Timothy Frasca ◽

Curtis Dolezal ◽

Ivan Balan

Keyword(s):

High Risk ◽

Sexual Partners ◽

Risk Of Infection ◽

Over The Counter

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EVO100 prevents chlamydia and gonorrhea in women at high risk of infection

American Journal of Obstetrics and Gynecology ◽

10.1016/j.ajog.2021.03.005 ◽

2021 ◽

Author(s):

B. Todd Chappell ◽

Leandro A. Mena ◽

Basem Maximos ◽

Scott Mollan ◽

Kelly Culwell ◽

...

Keyword(s):

High Risk ◽

Risk Of Infection

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Local Antibiotic Therapy to Reduce Infection After Operative Treatment of Fractures at High Risk of Infection

Journal of Orthopaedic Trauma ◽

10.1097/bot.0000000000001149 ◽

2018 ◽

Vol 32 (5) ◽

pp. e197

Keyword(s):

High Risk ◽

Antibiotic Therapy ◽

Operative Treatment ◽

Risk Of Infection ◽

Local Antibiotic ◽

Local Antibiotic Therapy

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Adult Javanese migrants to Indonesian Papua at high risk of severe disease caused by malaria

Epidemiology and Infection ◽

10.1017/s0950268803008422 ◽

2003 ◽

Vol 131 (1) ◽

pp. 791-797 ◽

Cited By ~ 16

Author(s):

J. K. BAIRD ◽

H. BASRI ◽

P. WEINA ◽

J. D. MAGUIRE ◽

M. J. BARCUS ◽

...

Keyword(s):

Relative Risk ◽

High Risk ◽

Severe Malaria ◽

Chronic Exposure ◽

Severe Disease ◽

Risk Of Infection ◽

Initial Exposure ◽

The Third ◽

Endemic Malaria

Migrants from Java arrive in hyperendemic Papua, Indonesia lacking exposure to endemic malaria. We evaluated records of evacuation to hospital with a diagnosis of severe malaria from a transmigration village in northeastern Papua. During the first 30 months, 198 residents with severe disease were evacuated (7·5 evacuations/100 person-years). During this period the risk of evacuation for adults (>15 years of age) was 2·8. (95% CI=2·1–3·8; P<0·0001) relative to children, despite apparently equal exposure to risk of infection. Relative risk (RR) for adults was greatest during the first 6 months (RR>16; 95% CI[ges ]2·0–129; P=0·0009), and diminished during the second 6 months (RR=9·4; 95% CI=2·7–32·8; P<0·0001) and the third 6 months (RR=3·7; 95% CI=1·7–7·9; P=0·0004). During the next two 6-month intervals, the RR for adults was 1·6 and 1·5 (95% CI range 0·8–2·6; P<0·18). Adults lacking chronic exposure were far more likely to progress to severe disease compared to children during initial exposure, but not after chronic exposure to infection.

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