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1.
BMJ Open ; 12(1): e053327, 2022 01 17.
Article in English | MEDLINE | ID: covidwho-1627515

ABSTRACT

OBJECTIVE: To identify the key individual-level (demographics, attitudes, mobility) and contextual (COVID-19 case numbers, tiers of mobility restrictions, urban districts) determinants of adopting the NHS COVID-19 contact tracing app and continued use overtime. DESIGN AND SETTING: A three-wave panel survey conducted in England in July 2020 (background survey), November 2020 (first measure of app adoption) and March 2021 (continued use of app and new adopters) linked with official data. PARTICIPANTS: N=2500 adults living in England, representative of England's population in terms of regional distribution, age and gender (2011 census). PRIMARY OUTCOME: Repeated measures of self-reported app usage. ANALYTICAL APPROACH: Multilevel logistic regression linking a range of individual level (from survey) and contextual (from linked data) determinants to app usage. RESULTS: We observe initial app uptake at 41%, 95% CI (0.39% to 0.43%), and a 12% drop-out rate by March 2021, 95% CI (0.10% to 0.14%). We also found that 7% of nonusers as of wave 2 became new adopters by wave 3, 95% CI (0.05% to 0.08%). Initial uptake (or failure to use) of the app associated with social norms, privacy concerns and misinformation about third-party data access, with those living in postal districts with restrictions on mobility less likely to use the app. Perceived lack of transparent evidence of effectiveness was associated with drop-out of use. In addition, those who trusted the government were more likely to adopt in wave 3 as new adopters. CONCLUSIONS: Successful uptake of the contact tracing app should be evaluated within the wider context of the UK Government's response to the crisis. Trust in government is key to adoption of the app in wave 3 while continued use is linked to perceptions of transparent evidence. Providing clear information to address privacy concerns could increase uptake, however, the disparities in continued use among ethnic minority participants needs further investigation.


Subject(s)
COVID-19 , Mobile Applications , Adult , Contact Tracing , Humans , Minority Groups , SARS-CoV-2 , Semantic Web
3.
Front Public Health ; 9: 645798, 2021.
Article in English | MEDLINE | ID: covidwho-1608747

ABSTRACT

Introduction: Close contacts have become a potential threat to the spread of coronavirus disease 2019 (COVID-19). The purpose of this study was to understand the epidemiological characteristics of close contacts of confirmed or suspected cases of COVID-19 in the surrounding cities of Chengdu, China, so as to provide a basis for the management strategy of close contacts. Methods: Close contacts were determined through epidemiological investigation of indicated cases, and relevant information was entered in the "Close Contact Information Management System." Retrospective data of close contacts from January 22 to May 1, 2020 were collected and organized. Meanwhile, the contact mode, isolation mode, and medical outcome of close contacts were descriptively analyzed. Results: A total of 986 close contacts were effectively traced, with an average age of (36.69 ± 16.86) years old, who were mainly distributed in cities of eastern Chengdu. The frequency of contact was mainly occasional contact, 80.42% of them were relatives and public transportation personnel. Besides, the time of tracking close contacts and feedback was (10.64 ± 5.52) and (7.19 ± 6.11) days, respectively. A total of seven close contacts were converted to confirmed cases. Conclusions: Close contacts of COVID-19 have a risk of invisible infection. Early control of close contacts may be helpful to control the epidemic of COVID-19.


Subject(s)
COVID-19 , Adult , China/epidemiology , Cities , Contact Tracing , Humans , Middle Aged , Retrospective Studies , SARS-CoV-2 , Young Adult
4.
BMC Public Health ; 22(1): 13, 2022 01 05.
Article in English | MEDLINE | ID: covidwho-1607916

ABSTRACT

BACKGROUND: Individual behavioural decisions are responses to a person's perceived social norms that could be shaped by both their physical and social environment. In the context of the COVID-19 pandemic, these environments correspond to epidemiological risk from contacts and the social construction of risk by communication within networks of friends. Understanding the circumstances under which the influence of these different social networks can promote the acceptance of non-pharmaceutical interventions and consequently the adoption of protective behaviours is critical for guiding useful, practical public health messaging. METHODS: We explore how information from both physical contact and social communication layers of a multiplex network can contribute to flattening the epidemic curve in a community. Connections in the physical contact layer represent opportunities for transmission, while connections in the communication layer represent social interactions through which individuals may gain information, e.g. messaging friends. RESULTS: We show that maintaining focus on awareness of risk among each individual's physical contacts promotes the greatest reduction in disease spread, but only when an individual is aware of the symptoms of a non-trivial proportion of their physical contacts (~ ≥ 20%). Information from the social communication layer without was less useful when these connections matched less well with physical contacts and contributed little in combination with accurate information from physical contacts. CONCLUSIONS: We conclude that maintaining social focus on local outbreak status will allow individuals to structure their perceived social norms appropriately and respond more rapidly when risk increases. Finding ways to relay accurate local information from trusted community leaders could improve mitigation even where more intrusive/costly strategies, such as contact-tracing, are not possible.


Subject(s)
COVID-19 , Epidemics , Communication , Contact Tracing , Humans , Pandemics , SARS-CoV-2
6.
Med Lav ; 112(6): 429-435, 2021 Dec 23.
Article in English | MEDLINE | ID: covidwho-1596134

ABSTRACT

BACKGROUND: This study aimed to investigate SARS-CoV-2 transmission among co-workers at the University of Genoa, Italy, during the second COVID-19 pandemic wave. METHODS: A cross-sectional study was carried out in October 2020 - March 2021: RT-PCR confirmed cases of COVID-19 notified to the Occupational Health Service were included in the analysis. RESULTS: Among the n = 201 notified cases, contact tracing of n = 53 individuals identified n = 346 close contacts. The household setting (IRR = 36.8; 95% CI: 4.9-276.8; p < 0.001) and sharing eating areas (IRR = 19.5; 95% CI: 2.5-153.9; p = 0.005) showed the highest Secondary Attack Rates (SARs) compared to the office setting. Fatigue (IRR= 17.1; 95% CI: 5.2-55.8; p < 0.001), gastrointestinal symptoms (IRR= 6.6; 95% CI: 2.9-15.2; p< 0.001) and cough (IRR= 8.2; 95% CI: 3.7-18.2; p= p< 0.001) were associated with transmission of infection. Polysymptomatic cases (IRR= 23.1; 95% CI: 3.1-169.2; p = 0.02) were more likely to transmit the infection. Among COVID-19 index cases aged >60 years (OR = 7.7; 95% CI: 1.9-31.9; p = 0.0046) SARs were higher than in other age groups. Wearing respiratory protections by both the case and the close contact resulted an effective measure compared with no use (IRR = 0.08; 95% CI: 0.03-0.2; p = < 0.0001). CONCLUSIONS: Accurate infection monitoring and contact tracing was useful to identify the main situations Conclusions: Accurate infection monitoring and contact tracing was useful to identify the main situations of SARS-CoV-2 transmission in the workplace, and hence for risk assessment and prevention programs.


Subject(s)
COVID-19 , Contact Tracing , Cross-Sectional Studies , Humans , Pandemics , SARS-CoV-2
7.
Am J Public Health ; 112(1): 43-47, 2022 01.
Article in English | MEDLINE | ID: covidwho-1594512

ABSTRACT

When COVID-19 cases surge, identifying ways to improve the efficiency of contact tracing and prioritize vulnerable communities for isolation and quarantine support services is critical. During a fall 2020 COVID-19 resurgence in San Francisco, California, prioritization of telephone-based case investigation by zip code and using a chatbot to screen for case participants who needed isolation support reduced the number of case participants who would have been assigned for a telephone interview by 31.5% and likely contributed to 87.5% of Latinx case participants being successfully interviewed. (Am J Public Health. 2022;112(1):43-47. https://doi.org/10.2105/AJPH.2021.306563).


Subject(s)
COVID-19/epidemiology , COVID-19/prevention & control , Contact Tracing/methods , Humans , SARS-CoV-2 , San Francisco/epidemiology , Technology , Telephone
8.
PLoS One ; 16(12): e0261330, 2021.
Article in English | MEDLINE | ID: covidwho-1581751

ABSTRACT

Coronavirus disease 2019 (COVID-19) is an infectious disease of humans caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Since the first case was identified in China in December 2019 the disease has spread worldwide, leading to an ongoing pandemic. In this article, we present an agent-based model of COVID-19 in Luxembourg, and use it to estimate the impact, on cases and deaths, of interventions including testing, contact tracing, lockdown, curfew and vaccination. Our model is based on collation, with agents performing activities and moving between locations accordingly. The model is highly heterogeneous, featuring spatial clustering, over 2000 behavioural types and a 10 minute time resolution. The model is validated against COVID-19 clinical monitoring data collected in Luxembourg in 2020. Our model predicts far fewer cases and deaths than the equivalent equation-based SEIR model. In particular, with R0 = 2.45, the SEIR model infects 87% of the resident population while our agent-based model infects only around 23% of the resident population. Our simulations suggest that testing and contract tracing reduce cases substantially, but are less effective at reducing deaths. Lockdowns are very effective although costly, while the impact of an 11pm-6am curfew is relatively small. When vaccinating against a future outbreak, our results suggest that herd immunity can be achieved at relatively low coverage, with substantial levels of protection achieved with only 30% of the population fully immune. When vaccinating in the midst of an outbreak, the challenge is more difficult. In this context, we investigate the impact of vaccine efficacy, capacity, hesitancy and strategy. We conclude that, short of a permanent lockdown, vaccination is by far the most effective way to suppress and ultimately control the spread of COVID-19.


Subject(s)
COVID-19/epidemiology , Pandemics/prevention & control , Quarantine/statistics & numerical data , Vaccination/statistics & numerical data , Adolescent , Adult , Aged , Child , Child, Preschool , Contact Tracing/statistics & numerical data , Humans , Immunity, Herd , Infant , Infant, Newborn , Luxembourg/epidemiology , Masks/statistics & numerical data , Middle Aged , Young Adult
9.
Sensors (Basel) ; 22(1)2021 Dec 30.
Article in English | MEDLINE | ID: covidwho-1580503

ABSTRACT

The COVID-19 Pandemic has punched a devastating blow on the majority of the world's population. Millions of people have been infected while hundreds of thousands have died of the disease throwing many families into mourning and other psychological torments. It has also crippled the economy of many countries of the world leading to job losses, high inflation, and dwindling Gross Domestic Product (GDP). The duo of social distancing and contact tracing are the major technological-based non-pharmaceutical public health intervention strategies adopted for combating the dreaded disease. These technologies have been deployed by different countries around the world to achieve effective and efficient means of maintaining appropriate distance and tracking the transmission pattern of the diseases or identifying those at high risk of infecting others. This paper aims to synthesize the research efforts on contact tracing and social distancing to minimize the spread of COVID-19. The paper critically and comprehensively reviews contact tracing technologies, protocols, and mobile applications (apps) that were recently developed and deployed against the coronavirus disease. Furthermore, the paper discusses social distancing technologies, appropriate methods to maintain distances, regulations, isolation/quarantine, and interaction strategies. In addition, the paper highlights different security/privacy vulnerabilities identified in contact tracing and social distancing technologies and solutions against these vulnerabilities. We also x-rayed the strengths and weaknesses of the various technologies concerning their application in contact tracing and social distancing. Finally, the paper proposed insightful recommendations and open research directions in contact tracing and social distancing that could assist researchers, developers, and governments in implementing new technological methods to combat the menace of COVID-19.


Subject(s)
COVID-19 , Contact Tracing , Humans , Pandemics , Physical Distancing , SARS-CoV-2
10.
Sci Rep ; 11(1): 24443, 2021 12 27.
Article in English | MEDLINE | ID: covidwho-1585775

ABSTRACT

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, [Formula: see text], and in the city, [Formula: see text], 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, [Formula: see text], during the same period, was systematically higher than [Formula: see text]. This result reinforces the need for special public transportation policies for highly exposed groups of people.


Subject(s)
COVID-19/transmission , Contact Tracing/methods , Brazil/epidemiology , COVID-19/epidemiology , COVID-19/virology , Disease Outbreaks , Health Personnel/statistics & numerical data , Humans , Models, Theoretical , SARS-CoV-2/isolation & purification , Transportation
11.
J Med Internet Res ; 23(2): e25525, 2021 02 08.
Article in English | MEDLINE | ID: covidwho-1576031

ABSTRACT

BACKGROUND: The main German-speaking countries (Germany, Austria, and Switzerland) have implemented digital contact tracing apps to assist the authorities with COVID-19 containment strategies. Low user rates for these apps can affect contact tracing and, thus, its usefulness in controlling the spread of the novel coronavirus. OBJECTIVE: This study aimed to assess the early perceptions of people living in the German-speaking countries and compare them with the frames portrayed in the newspapers during the first wave of the COVID-19 pandemic. METHODS: We conducted qualitative interviews with 159 participants of the SolPan project. Of those, 110 participants discussed contact tracing apps and were included in this study. We analyzed articles regarding contact tracing apps from 12 newspapers in the German-speaking countries. RESULTS: Study participants perceived and newspaper coverage in all German-speaking countries framed contact tracing apps as governmental surveillance tools and embedded them in a broader context of technological surveillance. Participants identified trust in authorities, respect of individual privacy, voluntariness, and temporary use of contact tracing apps as prerequisites for democratic compatibility. Newspapers commonly referenced the use of such apps in Asian countries, emphasizing the differences in privacy regulation among these countries. CONCLUSIONS: The uptake of digital contact tracing apps in German-speaking countries may be undermined due to privacy risks that are not compensated by potential benefits and are rooted in a deeper skepticism towards digital tools. When authorities plan to implement new digital tools and practices in the future, they should be very transparent and proactive in communicating their objectives and the role of the technology-and how it differs from other, possibly similar, tools. It is also important to publicly address ethical, legal, and social issues related to such technologies prior to their launch.


Subject(s)
COVID-19/epidemiology , Contact Tracing/methods , Mobile Applications , Adolescent , Adult , Aged , Germany/epidemiology , Humans , Middle Aged , Perception , SARS-CoV-2/isolation & purification , Young Adult
12.
Asia Pac J Public Health ; 33(8): 945-948, 2021 11.
Article in English | MEDLINE | ID: covidwho-1575963

ABSTRACT

The current COVID-19 (coronavirus disease 2019) pandemic has perpetuated a worldwide tussle to control this infection and minimizing death toll and economic damages. The year 2020 would always be remembered as a year of war against a virus, but it would also be marked as a year showing upsurge of technology evolution to deal with infections. Contact tracing has emerged as a new buzzword. Contact tracing digital tools have been introduced worldwide to prevent transmission. In this article, we have outlined various contact tracing apps being used globally, which are rated according to their safety, privacy, and efficacy.


Subject(s)
COVID-19 , Mobile Applications , Contact Tracing , Humans , Pandemics , SARS-CoV-2
13.
J Med Internet Res ; 23(2): e25893, 2021 02 08.
Article in English | MEDLINE | ID: covidwho-1575197

ABSTRACT

BACKGROUND: Contact tracing apps are an essential component of an effective COVID-19 testing strategy to counteract the spread of the pandemic and thereby avoid overburdening the health care system. As the adoption rates in several regions are undesirable, governments must increase the acceptance of COVID-19 tracing apps in these times of uncertainty. OBJECTIVE: Building on the Uncertainty Reduction Theory (URT), this study aims to investigate how uncertainty reduction measures foster the adoption of COVID-19 tracing apps and how their use affects the perception of different risks. METHODS: Representative survey data were gathered at two measurement points (before and after the app's release) and analyzed by performing covariance-based structural equation modeling (n=1003). RESULTS: We found that uncertainty reduction measures in the form of the transparency dimensions disclosure and accuracy, as well as social influence and trust in government, foster the adoption process. The use of the COVID-19 tracing app in turn reduced the perceived privacy and performance risks but did not reduce social risks and health-related COVID-19 concerns. CONCLUSIONS: This study contributes to the mass adoption of health care technology and URT research by integrating interactive communication measures and transparency as a multidimensional concept to reduce different types of uncertainty over time. Furthermore, our results help to derive communication strategies to promote the mass adoption of COVID-19 tracing apps, thus detecting infection chains and allowing intelligent COVID-19 testing.


Subject(s)
COVID-19/epidemiology , COVID-19/psychology , Contact Tracing/methods , Mobile Applications , Empirical Research , Humans , SARS-CoV-2/isolation & purification , Uncertainty
14.
J Med Internet Res ; 23(2): e23467, 2021 02 09.
Article in English | MEDLINE | ID: covidwho-1574242

ABSTRACT

BACKGROUND: Many countries across the globe have released their own COVID-19 contact tracing apps. This has resulted in the proliferation of several apps that used a variety of technologies. With the absence of a standardized approach used by the authorities, policy makers, and developers, many of these apps were unique. Therefore, they varied by function and the underlying technology used for contact tracing and infection reporting. OBJECTIVE: The goal of this study was to analyze most of the COVID-19 contact tracing apps in use today. Beyond investigating the privacy features, design, and implications of these apps, this research examined the underlying technologies used in contact tracing apps. It also attempted to provide some insights into their level of penetration and to gauge their public reception. This research also investigated the data collection, reporting, retention, and destruction procedures used by each of the apps under review. METHODS: This research study evaluated 13 apps corresponding to 10 countries based on the underlying technology used. The inclusion criteria ensured that most COVID-19-declared epicenters (ie, countries) were included in the sample, such as Italy. The evaluated apps also included countries that did relatively well in controlling the outbreak of COVID-19, such as Singapore. Informational and unofficial contact tracing apps were excluded from this study. A total of 30,000 reviews corresponding to the 13 apps were scraped from app store webpages and analyzed. RESULTS: This study identified seven distinct technologies used by COVID-19 tracing apps and 13 distinct apps. The United States was reported to have released the most contact tracing apps, followed by Italy. Bluetooth was the most frequently used underlying technology, employed by seven apps, whereas three apps used GPS. The Norwegian, Singaporean, Georgian, and New Zealand apps were among those that collected the most personal information from users, whereas some apps, such as the Swiss app and the Italian (Immuni) app, did not collect any user information. The observed minimum amount of time implemented for most of the apps with regard to data destruction was 14 days, while the Georgian app retained records for 3 years. No significant battery drainage issue was reported for most of the apps. Interestingly, only about 2% of the reviewers expressed concerns about their privacy across all apps. The number and frequency of technical issues reported on the Apple App Store were significantly more than those reported on Google Play; the highest was with the New Zealand app, with 27% of the reviewers reporting technical difficulties (ie, 10% out of 27% scraped reviews reported that the app did not work). The Norwegian, Swiss, and US (PathCheck) apps had the least reported technical issues, sitting at just below 10%. In terms of usability, many apps, such as those from Singapore, Australia, and Switzerland, did not provide the users with an option to sign out from their apps. CONCLUSIONS: This article highlighted the fact that COVID-19 contact tracing apps are still facing many obstacles toward their widespread and public acceptance. The main challenges are related to the technical, usability, and privacy issues or to the requirements reported by some users.


Subject(s)
Attitude , COVID-19/prevention & control , Contact Tracing/methods , Mobile Applications , Privacy , Australia , Data Collection , Disease Outbreaks , Geographic Information Systems , Georgia (Republic) , Humans , Italy , New Zealand , Norway , SARS-CoV-2 , Singapore , Switzerland , Technology , United States , Wireless Technology
15.
J Prev Med Hyg ; 62(3): E592-E597, 2021 Sep.
Article in English | MEDLINE | ID: covidwho-1574106

ABSTRACT

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is the causative agent of pandemic coronavirus disease 2019 (COVID 19) Protection from virus exposure in children's hospital is a pivotal aspect of SARS-COV-2 pandemic control. Healthcare workers (HCW) could play an important role in viral infection in-hospital spread. Infection control measures were thus implemented to protect fragile patients and healthcare workers.We retrospectively described a HCW infectionscase-series due to SARS-CoV-2 from February 24th to July 31stat the IRCCS Istituto Giannina Gaslini. Seven separate cases of SARS-CoV-2 infection were observed among healthcare workers, with a total of 395 contacts, and 23 (6%) secondary case. A program of contact tracing and quarantine of SARS-CoV-2 positive HCW, screening of asymptomatic HCW, use of surgical masks, hand hygiene, social distancing and use of PPE in COVID-19 cases assistance prevented the spread of the virus to patients and blocked the diffusion within the hospital.


Subject(s)
COVID-19 , Hand Hygiene , Child , Contact Tracing , Health Personnel , Hospitals, Pediatric , Humans , Masks , Physical Distancing , Retrospective Studies , SARS-CoV-2
16.
Front Public Health ; 9: 782296, 2021.
Article in English | MEDLINE | ID: covidwho-1572344

ABSTRACT

Introduction: Case investigation and contact tracing are important tools to limit the spread of SARS-CoV-2, particularly when implemented efficiently. Our objective was to evaluate participation in and timeliness of COVID-19 contact tracing and whether these measures changed over time. Methods: We retrospectively assessed COVID-19 case investigation and contact tracing surveillance data from the Washington State centralized program for August 1-31, 2020 and October 1-31, 2020. We combined SARS-CoV-2 testing reports with contact tracing data to compare completeness, reporting of contacts, and program timeliness. Results: For August and October respectively, 4,600 (of 12,521) and 2,166 (of 16,269) individuals with COVID-19 were referred to the state program for case investigation. Investigators called 100% of referred individuals; 65% (August) and 76% (October) were interviewed. Of individuals interviewed, 33% reported contacts in August and 45% in October, with only mild variation by age, sex, race/ethnicity, and urbanicity. In August, 992 individuals with COVID-19 reported a total of 2,584 contacts (mean, 2.6), and in October, 739 individuals reported 2,218 contacts (mean, 3.0). Among contacts, 86% and 78% participated in interviews for August and October. The median time elapsed from specimen collection to contact interview was 4 days in August and 3 days in October, and from symptom onset to contact interview was 7 days in August and 6 days in October. Conclusions: While contact tracing improved with time, the proportion of individuals disclosing contacts remained below 50% and differed minimally by demographic characteristics. The longest time interval occurred between symptom onset and test result notification. Improving elicitation of contacts and timeliness of contact tracing may further decrease SARS-CoV-2 transmission.


Subject(s)
COVID-19 , COVID-19 Testing , Contact Tracing , Humans , Retrospective Studies , SARS-CoV-2 , Washington/epidemiology
17.
PLoS One ; 16(12): e0261335, 2021.
Article in English | MEDLINE | ID: covidwho-1571992

ABSTRACT

The spread of infectious diseases is highly related to the structure of human networks. Analyzing the contact network of patients can help clarify the path of virus transmission. Based on confirmed cases of COVID-19 in two major tourist provinces in southern China (Hainan and Yunnan), this study analyzed the epidemiological characteristics and dynamic contact network structure of patients in these two places. Results show that: (1) There are more female patients than males in these two districts and most are imported cases, with an average age of 45 years. Medical measures were given in less than 3 days after symptoms appeared. (2) The whole contact network of the two areas is disconnected. There are a small number of transmission chains in the network. The average values of degree centrality, betweenness centrality, and PageRank index are small. Few patients have a relatively high contact number. There is no superspreader in the network.


Subject(s)
COVID-19/transmission , Contact Tracing/methods , Adolescent , Adult , Aged , Algorithms , Child , Child, Preschool , China/epidemiology , Female , Humans , Infant , Male , Middle Aged , Social Network Analysis , Tourism , Young Adult
18.
Int J Environ Res Public Health ; 18(18)2021 09 08.
Article in English | MEDLINE | ID: covidwho-1547312

ABSTRACT

The aim of this study is to assess the effect of contact time, contact distance and the use of personal protective equipment on the determination of SARS-CoV-2 infection in healthcare workers (HCWs). This study consists of an analysis of data gathered for safety reasons at the Sapienza Teaching Hospital Policlinico Umberto I in Rome through the surveillance system that was put into place after the worsening of the COVID-19 pandemic. The studied subjects consist of HCWs who were put under health surveillance, i.e., all employees who were in contact with subjects who were confirmed to have tested positive for SARS-CoV-2. The HCWs under surveillance were monitored for a period encompassing ten days after the date of contact, during which they undertook nasopharyngeal swab tests analysed through RT-PCR (RealStar® SARS-CoV-2 Altona Diagnostic-Germany). Descriptive and univariate analyses have been undertaken, considering the following as risk factors: (a) no personal protective equipment use (PPE); (b) Distance < 1 m between the positive and contact persons; (c) contact time > 15'. Finally, a Cox regression and an analysis of the level of synergism between factors, as specified by Rothman, were carried out. We analysed data from 1273 HCWs. Of these HCWs, 799 (62.8%) were females, with a sample average age of 47.8 years. Thirty-nine (3.1%) tested positive during surveillance. The overall incidence rate was 0.4 per 100 person-days. Time elapsed from the last exposure and a positive RT-PCR result ranged from 2 to 17 days (mean = 7, median = 6 days). In the univariate analysis, a distance <1 m and a contact time > 15' proved to be risk factors for the SARS-CoV-2 infection, with a hazard ratio (HR) of 2.62 (95% CI: 1.11-6.19) and 3.59 (95% IC: 1.57-8.21), respectively. The synergism analysis found the highest synergism between the "no PPE use" x "Contact time". The synergy index S remains strongly positive also in the analysis of the factors "no PPE use" x "Distance" and "Time of contact" x "Distance". This study confirms the absolute need to implement safety protocols during the pandemic and to use the correct PPE within health facilities in order to prevent SARS-CoV-2 infection. The analysis shows that among the factors considered (contact time and distance, no use of PPE), there is a strong synergistic effect.


Subject(s)
COVID-19 , Personal Protective Equipment , Contact Tracing , Female , Follow-Up Studies , Health Personnel , Humans , Infectious Disease Transmission, Patient-to-Professional/prevention & control , Middle Aged , Pandemics , SARS-CoV-2
19.
Zhonghua Liu Xing Bing Xue Za Zhi ; 42(10): 1757-1762, 2021 Oct 10.
Article in Chinese | MEDLINE | ID: covidwho-1534275

ABSTRACT

Objective: To analyze the epidemiological characteristics of close contacts of COVID-19 cases and infection-related risk factors in Beijing and provide evidences for COVID-19 prevention and control. Methods: A total of 20 681 close contacts of COVID-19 cases, who had exposures during January 6, 2020 to February 15, 2021, were traced in Beijing. The information about their demographic characteristics, exposure history, and quarantine outcomes were collected and analyzed with descriptive statistics. The logistic regression analysis was used to identify the risk factors for COVID-19. Results: The infection rate SARS-CoV-2 in close contacts was 2.16% (447/20 681). The age M(P25, P75) was 35 (27, 49) years. The majority of the close contacts were aged 20-59 years, accounting for 81.77% (16 912/20 681). Centralized isolation was the major type of medical observation, accounting for 82.15% (16 989/20 681). Among the exposure types, working and studying in the same room (16.06%, 3 322/20 681), sharing same transport vehicle (12.88%, 2 664/20 681), performing diagnosis and treatment nursing (7.80%,1 612/20 681), and living together (7.23%,1 495/20 681), accounting for 43.96% (9 093/20 681). The index cases included staff (19.34%, 3 999/20 681), the unemployed (17.34%, 3 586/20 681), people engaged in business service (13.85%, 2 864/20 681), people engaged in food service (10.77%, 2 228/20 681), their close contacts accounted for 61.30% (12 677/20 681). Multivariate logistic regression analysis showed that compared with other types of exposure, the risk factors for infection were having meal together (OR=3.96, 95%CI: 2.30-6.83) and living together (OR=6.41, 95%CI:4.48-9.17); Compared with the other occupations, the index case being engaged in food service (OR=3.06, 95%CI:1.29-7.25) and teacher (OR=4.94, 95%CI:1.43-17.08) were risk factors for the infection. Conclusions: The main environmental exposure types of SARS-CoV-2 infection in close contacts were having meal together and living together. Contact with the index case being engaged in food service and teacher increased the risk for COVID-19. Comprehensive prevention and control measures such as centralized isolation and vaccination should be continued.


Subject(s)
COVID-19 , Beijing , Contact Tracing , Humans , Risk Factors , SARS-CoV-2
20.
Int J Public Health ; 66: 1603992, 2021.
Article in English | MEDLINE | ID: covidwho-1533731

ABSTRACT

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.


Subject(s)
COVID-19 , Contact Tracing , Mobile Applications , Quarantine , Adult , COVID-19/epidemiology , COVID-19/prevention & control , Cohort Studies , Contact Tracing/methods , Female , Humans , Male , Middle Aged , Mobile Applications/statistics & numerical data , Quarantine/statistics & numerical data , Switzerland/epidemiology , Time Factors
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