The first 2 months of COVID-19 contact tracing in the Northern Territory of Australia, March–April 2020

2020 ◽  
Vol 44 ◽  
Author(s):  
Anthony DK Draper ◽  
Karen E Dempsey ◽  
Rowena H Boyd ◽  
Emma M Childs ◽  
Hayley M Black ◽  
...  
Keyword(s):  
Disease Control ◽  
Healthcare Workers ◽  
Northern Territory ◽  
Contact Tracing ◽  
Cruise Ship ◽  
Disease Symptoms ◽  
Household Contacts ◽  
Close Contacts

The Northern Territory (NT) Centre for Disease Control (CDC) undertook contact tracing of all notified cases of coronavirus disease 2019 (COVID-19) within the Territory. There were 28 cases of COVID-19 notified in the NT between 1 March and 30 April 2020. In total 527 people were identified as close contacts over the same period; 493 were successfully contacted; 445 were located in the NT and were subsequently quarantined and monitored for disease symptoms daily for 14 days after contact with a confirmed COVID-19 case. Of these 445 close contacts, 4 tested positive for COVID-19 after developing symptoms; 2/46 contacts who were cruise ship passengers (4.3%, 95% CI 0.5–14.8%) and 2/51 household contacts (3.9%, 95% CI 0.5–13.5%). None of the 326 aircraft passengers or 4 healthcare workers who were being monitored in the NT as close contacts became cases.

scholarly journals Source and symptoms of COVID-19 among hospital workers in Milan

2020 ◽  
Vol 70 (9) ◽  
pp. 672-679 ◽  
Author(s):  
S Mandić-Rajčević ◽  
F Masci ◽  
E Crespi ◽  
S Franchetti ◽  
A Longo ◽  
...  
Keyword(s):  
Healthcare Workers ◽  
Case Series ◽  
Nursing Assistants ◽  
Vulnerable Groups ◽  
Contact Tracing ◽  
Public Healthcare ◽  
Nasopharyngeal Swab ◽  
Infection Rates ◽  
Sources Of Infection ◽  
Close Contacts

Abstract Background Healthcare workers (HCWs) are commonly infected by SARS-CoV-2 and represent one of the most vulnerable groups. Adequate prevention strategies are necessary to guarantee HCWs’ safety, as well as to prevent dissemination of the infection among patients. Aims To describe a case series of SARS-CoV-2-positive HCWs in a large public healthcare organization in Milan (Italy) during the most devastating weeks of the epidemic and analyse the sources, symptoms and duration of SARS-CoV-2 infection. Methods This study included 172 SARS-CoV-2-positive HCWs who were infected between the 25th of February and the 7th of April 2020. A nasopharyngeal swab (NPS) and RT-PCR were used to indicate. Results Initially, the most common sources of infection were other positive HCWs (49%). Medical doctors and nursing assistants were most frequently infected, with infection rates of 53/1000 and 50/1000, respectively. COVID-19 departments were less affected than internal medicine, surgery, intensive care, or emergency room. The most commonly reported symptom was mild cough, while loss of smell (anosmia) and loss of taste (ageusia) were reported as moderate and severe by 30–40% of HCWs. The time necessary for 50% of workers to recover from the infection was 23 days, while it took 41 days for 95% of HCWs to become virus-free. Conclusions HCWs are commonly infected due to close contacts with other positive HCWs, and non-COVID departments were most affected. Most HCWs were asymptomatic or subclinical but contact tracing and testing of asymptomatic HCWs help identify and isolate infected workers.

scholarly journals Tracing contacts to evaluate the transmission of COVID-19 from highly exposed individuals in public transportation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Caio Ponte ◽  
Humberto A. Carmona ◽  
Erneson A. Oliveira ◽  
Carlos Caminha ◽  
Antonio S. Lima ◽  
...  
Keyword(s):  
Public Transportation ◽  
Healthcare Workers ◽  
Time Windows ◽  
Mean Field ◽  
Contact Tracing ◽  
Reproduction Numbers ◽  
Consecutive Time ◽  
Longitudinal Comparison ◽  
The City ◽  
Close Contacts

AbstractWe investigate, through a data-driven contact tracing model, the transmission of COVID-19 inside buses during distinct phases of the pandemic in a large Brazilian city. From this microscopic approach, we recover the networks of close contacts within consecutive time windows. A longitudinal comparison is then performed by upscaling the traced contacts with the transmission computed from a mean-field compartmental model for the entire city. Our results show that the effective reproduction numbers inside the buses, $$Re^{bus}$$ R e bus , and in the city, $$Re^{city}$$ R e city , followed a compatible behavior during the first wave of the local outbreak. Moreover, by distinguishing the close contacts of healthcare workers in the buses, we discovered that their transmission, $$Re^{health}$$ R e health , during the same period, was systematically higher than $$Re^{bus}$$ R e bus . This result reinforces the need for special public transportation policies for highly exposed groups of people.

scholarly journals Epidemiological characteristics of COVID-19 cases among Indians residing in Kuwait

2021 ◽  
Author(s):  
Jagan K. Baskaradoss ◽  
Aishah Alsumait ◽  
Shaheer Malik ◽  
Jitendra Ariga ◽  
Amrita Geevarghese ◽  
...  
Keyword(s):  
Healthcare Workers ◽  
Contact Tracing ◽  
Indian Community ◽  
Asymptomatic Patients ◽  
Serial Interval ◽  
The World ◽  
Early Increase ◽  
The Mean ◽  
Epidemiological Characteristics ◽  
Close Contacts

Background: The coronavirus disease 2019 (COVID-19) pandemic has rapidly spread to most countries around the world. Disproportionate spread of COVID-19 among the Indian community in Kuwait prompted heightened surveillance in this community. Aims: To study the epidemiological characteristics of COVID-19 patients and their contacts among the Indian community in Kuwait. Methods: Data collection was done as a part of contact tracing efforts undertaken by the Kuwaiti Ministry of Health. Results: We analysed contact-tracing data for the initial 1348 laboratory-confirmed Indian patients and 6357 contacts (5681 close and 676 casual). The mean (standard deviation) age of the patients was 39.43 (10.5) years and 76.5% of the cases were asymptomatic or had only mild symptoms. Asymptomatic patients were significantly older [40.05 (10.42) years] than patients with severe symptoms [37.54 (10.54) years] (P = 0.024). About 70% of the patients were living in shared accommodation. Most of the close contacts were living in the same household, as compared with casual contacts, who were primarily workplace contacts (P < 0.001). Among the different occupations, healthcare workers had the highest proportion of cases (18.4%). Among the 216 pairs of cases with a clear relationship between the index and secondary cases, the mean serial interval was estimated to be 3.89 (3.69) days, with a median of 3 and interquartile range of 1–5 days. Conclusion: An early increase in the number of COVID-19 cases among the Indian community could be primarily attributed to crowded living conditions and the high proportion of healthcare workers in this community.

scholarly journals Sero-Prevalence of SARS-CoV-2 Antibodies in High-Risk Populations in Vietnam

2021 ◽  
Vol 18 (12) ◽  
pp. 6353
Author(s):  
Tasnim Hasan ◽  
Thach Ngoc Pham ◽  
Thu Anh Nguyen ◽  
Hien Thi Thu Le ◽  
Duyet Van Le ◽  
...  
Keyword(s):  
High Risk ◽  
Healthcare Workers ◽  
Close Contact ◽  
Contact Tracing ◽  
Community Members ◽  
Prevalence Survey ◽  
Household Contacts ◽  
Antibody Positivity ◽  
High Risk Populations ◽  
Low Prevalence

As a response to the coronavirus disease 2019 (COVID-19) pandemic, Vietnam enforced strict quarantine, contact tracing and physical distancing policies resulting in one of the lowest numbers of individuals infected with severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) globally. This study aimed to determine the prevalence of SARS-CoV-2 antibody positivity among high-risk populations in Vietnam. A prevalence survey was undertaken within four communities in Vietnam, where at least two COVID-19 cases had been confirmed. Participants were classified according to the location of exposure: household contacts, close contacts, community members, and healthcare workers (HCWs) responsible for treating COVID-19 cases. Participants completed a baseline questionnaire and SARS-CoV-2 IgG antibodies were quantified using a commercial assay. A total of 3049 community members and 149 health care workers consented to the study. Among 13 individuals who were seropositive (0.4%), five household contacts (5/27, 18.5%), one close contact (1/53, 1.9%), and seven community members (7/2954, 0.2%) had detectable SARS-CoV-2 antibodies. All HCWs were negative for SARS-CoV-2 antibodies. Participants were tested a median of 15.1 (interquartile range from 14.9 to 15.2) weeks after exposure. Our study found a low prevalence of SARS-CoV-2 antibodies in high-risk communities and healthcare workers in communities in Vietnam with known COVID-19 cases.

scholarly journals Adherence and Association of Digital Proximity Tracing App Notifications With Earlier Time to Quarantine: Results From the Zurich SARS-CoV-2 Cohort Study

2021 ◽  
Vol 66 ◽  
Author(s):  
Tala Ballouz ◽  
Dominik Menges ◽  
Hélène E. Aschmann ◽  
Anja Domenghino ◽  
Jan S. Fehr ◽  
...  
Keyword(s):  
Cohort Study ◽  
Population Based ◽  
Contact Tracing ◽  
Time To Event ◽  
Household Contacts ◽  
Close Contacts

Objectives: We aimed to evaluate the effectiveness of the SwissCovid digital proximity tracing (DPT) app in notifying exposed individuals and prompting them to quarantine earlier compared to individuals notified only by manual contact tracing (MCT).Methods: A population-based sample of cases and close contacts from the Zurich SARS-CoV-2 Cohort was surveyed regarding SwissCovid app use and SARS-CoV-2 exposure. We descriptively analyzed app adherence and effectiveness, and evaluated its effects on the time between exposure and quarantine among contacts using stratified multivariable time-to-event analyses.Results: We included 393 SARS-CoV-2 infected cases and 261 close contacts. 62% of cases reported using SwissCovid and among those, 88% received and uploaded a notification code. 71% of close contacts were app users, of which 38% received a warning. Non-household contacts notified by SwissCovid started quarantine 1 day earlier and were more likely to quarantine earlier than those not warned by the app (HR 1.53, 95% CI 1.15–2.03).Conclusion: These findings provide evidence that DPT may reach exposed contacts faster than MCT, with earlier quarantine and potential interruption of SARS-CoV-2 transmission chains.

scholarly journals Tracing contacts to evaluate the transmission of COVID-19 from highly exposed individuals in public transportation

2021 ◽  
Author(s):  
Caio Ponte ◽  
Humberto Carmona ◽  
Erneson Oliveira ◽  
Carlos Caminha ◽  
Antonio Lima Neto ◽  
...  
Keyword(s):  
Public Transportation ◽  
Healthcare Workers ◽  
Time Windows ◽  
Mean Field ◽  
Contact Tracing ◽  
Reproduction Numbers ◽  
Consecutive Time ◽  
Longitudinal Comparison ◽  
The City ◽  
Close Contacts

We investigate, through a data-driven contact tracing model, the transmission of COVID-19 inside buses during distinct phases of the pandemic in a large Brazilian city. From this microscopic approach, we recover the networks of close contacts within consecutive time windows. A longitudinal comparison is then performed by upscaling the traced contacts with the transmission computed from a mean-field compartmental model for the entire city. Our results show that the effective reproduction numbers inside the buses, Rebus, and in the city, Recity, followed a compatible behavior during the first wave of the local outbreak. Moreover, by distinguishing the close contacts of healthcare workers in the buses, we discovered that their transmission, Rehealth, during the same period, was systematically higher than Rebus. This result reinforces the need for special public transportation policies for highly exposed groups of people.

scholarly journals Digital proximity tracing app notifications lead to faster quarantine in non-household contacts: results from the Zurich SARS-CoV-2 Cohort Study

2020 ◽  
Author(s):  
Tala Ballouz ◽  
Dominik Menges ◽  
Helene E Aschmann ◽  
Anja Domenghino ◽  
Jan S Fehr ◽  
...  
Keyword(s):  
Cohort Study ◽  
Population Based ◽  
Contact Tracing ◽  
Household Contacts ◽  
Health Directorate ◽  
Multivariable Analyses ◽  
University Of Zurich ◽  
Exposure Setting ◽  
Index Cases ◽  
Close Contacts

AbstractBackgroundDigital proximity tracing (DPT) apps may warn exposed individuals faster than manual contact tracing (MCT), leading to earlier interruption of transmission chains through quarantine. However, it is yet unclear whether these apps lead to a reduction in transmissions under real-world conditions. This study aimed at evaluating whether the SwissCovid DPT app is effective in warning close contacts of SARS-CoV-2 infected cases and prompting them to quarantine earlier.MethodsA population-based sample of adult index cases and close contacts identified through MCT and enrolled in the Zurich SARS-CoV-2 Cohort study were surveyed regarding use of the SwissCovid app and SARS-CoV-2 exposure setting. We analyzed ooutcomes related to app effectiveness and adherence (i.e., receipt and uploading of notification codes by index cases; receipt of app warnings and steps taken by close contacts). Furthermore, we performed adjusted time-to-event analyses stratified by exposure setting to estimate the effect of the app on time between relevant exposure and entering quarantine among close contacts.FindingsWe included 393 index cases and 261 close contacts in the analysis. Among index cases using SwissCovid, 88% reported receiving and uploading a notification code in the app to trigger a warning among proximity contacts. Among close contacts using the app, 38% reported receiving an app warning due to the risk exposure. We found that non-household contacts who were notified by the app started quarantine at a median of 2 days after exposure, while those not notified started quarantine at a median of 3 days. In stratified multivariable analyses, app notified contacts had a greater probability of going into quarantine earlier than those without app notification (HR 1·53, 95% CI 1·15-2·03).InterpretationOur study showed that non-household contacts notified by the app started quarantine one day earlier than those not notified by the app. These findings constitute the first evidence that DPT may reach exposed contacts faster than MCT, leading to earlier quarantine and potential interruption of SARS-CoV-2 transmission chains.FundingCantonal Health Directorate Zurich, University of Zurich Foundation and the Swiss Federal Office of Public Health.

scholarly journals Household Secondary Attack Rate of COVID-19 and Associated Determinants

2020 ◽  
Author(s):  
Qin-Long Jing ◽  
Ming-Jin Liu ◽  
Jun Yuan ◽  
Zhou-Bin Zhang ◽  
An-Ran Zhang ◽  
...  
Keyword(s):  
Incubation Period ◽  
Attack Rate ◽  
Population Level ◽  
Human Movement ◽  
The Elderly ◽  
Contact Tracing ◽  
Infectious Period ◽  
Reproductive Number ◽  
Household Contacts ◽  
Close Contacts

AbstractBackgroundAs of April 2, 2020, the global reported number of COVID-19 cases has crossed over 1 million with more than 55,000 deaths. The household transmissibility of SARS-CoV-2, the causative pathogen, remains elusive.MethodsBased on a comprehensive contact-tracing dataset from Guangzhou, we estimated both the population-level effective reproductive number and individual-level secondary attack rate (SAR) in the household setting. We assessed age effects on transmissibility and the infectivity of COVID-19 cases during their incubation period.ResultsA total of 195 unrelated clusters with 212 primary cases, 137 nonprimary (secondary or tertiary) cases and 1938 uninfected close contacts were traced. We estimated the household SAR to be 13.8% (95% CI: 11.1-17.0%) if household contacts are defined as all close relatives and 19.3% (95% CI: 15.5-23.9%) if household contacts only include those at the same residential address as the cases, assuming a mean incubation period of 4 days and a maximum infectious period of 13 days. The odds of infection among children (<20 years old) was only 0.26 (95% CI: 0.13-0.54) times of that among the elderly (≥60 years old). There was no gender difference in the risk of infection. COVID-19 cases were at least as infectious during their incubation period as during their illness. On average, a COVID-19 case infected 0.48 (95% CI: 0.39-0.58) close contacts. Had isolation not been implemented, this number increases to 0.62 (95% CI: 0.51-0.75). The effective reproductive number in Guangzhou dropped from above 1 to below 0.5 in about 1 week.ConclusionSARS-CoV-2 is more transmissible in households than SARS-CoV and MERS-CoV, and the elderly ≥60 years old are the most vulnerable to household transmission. Case finding and isolation alone may be inadequate to contain the pandemic and need to be used in conjunction with heightened restriction of human movement as implemented in Guangzhou.

scholarly journals Tuberculosis contact investigation results among paediatric contacts in low-incidence settings in Finland

2021 ◽  
Author(s):  
Antti Kontturi ◽  
Satu Kekomäki ◽  
Eeva Ruotsalainen ◽  
Eeva Salo
Keyword(s):  
Early Diagnosis ◽  
Young Children ◽  
Large Scale ◽  
Index Case ◽  
Contact Tracing ◽  
Sputum Smear ◽  
Endemic Country ◽  
Household Contacts ◽  
Contact Investigation ◽  
Positive Index

AbstractTuberculosis (TB) risk is highest immediately after primary infection, and young children are vulnerable to rapid and severe TB disease. Contact tracing should identify infected children rapidly and simultaneously target resources effectively. We conducted a retrospective review of the paediatric TB contact tracing results in the Hospital District of Helsinki and Uusimaa from 2012 to 2016 and identified risk factors for TB disease or infection. Altogether, 121 index cases had 526 paediatric contacts of whom 34 were diagnosed with TB disease or infection. The maximum delay until first contact investigation visit among the household contacts under 5 years of age with either TB disease or infection was 7 days. The yield for TB disease or infection was 4.6% and 12.8% for household contacts, 0.5% and 0% for contacts exposed in a congregate setting and 1.4% and 5.0% for other contacts, respectively. Contacts born in a TB endemic country (aOR 3.07, 95% CI 1.10–8.57), with household exposure (aOR 2.96, 95% CI 1.33–6.58) or a sputum smear positive index case (aOR 3.96, 95% CI 1.20–13.03) were more likely to have TB disease or infection.Conclusions: Prompt TB investigations and early diagnosis can be achieved with a well-organised contact tracing structure. The risk for TB infection or disease was higher among contacts with household exposure, a sputum smear positive index case or born in a TB endemic country. Large-scale investigations among children exposed in congregate settings can result in a very low yield and should be cautiously targeted. What is Known:• Vulnerable young children are a high priority in contact tracing and should be evaluated as soon as possible after TB exposure What is New:• Prompt investigations for paediatric TB contacts and early diagnosis of infected children can be achieved with a well-organised contact tracing structure• Large-scale investigations among children exposed in congregate settings can result in a very low yield and should be cautiously targeted

scholarly journals Assessing testing strategies and duration of quarantine in contact tracing for SARS-CoV-2: a retrospective study of San Francisco’s COVID-19 contact tracing program, June- August, 2020

2021 ◽  
Author(s):  
M J A Reid ◽  
P Prado ◽  
H Brosnan ◽  
A Ernst ◽  
H Spindler ◽  
...  
Keyword(s):  
Retrospective Study ◽  
San Francisco ◽  
Contact Tracing ◽  
Testing Strategies ◽  
Close Contacts

Abstract We sought to assess the proportion of elicited close contacts diagnosed with COVID-19 at the start, and before exiting quarantine, in San Francisco, USA. From June 8th to August 31st, 6946 contacts were identified; 3008 (46.3%) tested, 940 (13.5%) tested positive; 90% tested positive in first 9 days of quarantine.

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