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1.
Am J Public Health ; 112(7): 1025-1033, 2022 Jul.
Article in English | MEDLINE | ID: mdl-35653650

ABSTRACT

Contact tracing-the process of identifying, isolating, and managing infected persons and their contacts-is a recognized public health measure for controlling the transmission of infectious diseases. In the context of the COVID-19 pandemic, contact tracing has received intense attention. We provide a brief overview of the history of contact tracing during several major disease outbreaks in the past century: syphilis and other sexually transmitted infections, HIV infection, tuberculosis, Ebola virus disease, and COVID-19. Our discussion on the barriers to and facilitators of contact tracing offers a perspective on societal and institutional roles and dynamics, stigma as a major barrier to effective tracing efforts, and how the nature and epidemiology of the infection itself can affect its success. We explore the evolution and adaptation of contact tracing and provide insights for future programming and research. (Am J Public Health. 2022;112(7):1025-1033. https://doi.org/10.2105/AJPH.2022.306842).


Subject(s)
COVID-19 , HIV Infections , Hemorrhagic Fever, Ebola , COVID-19/epidemiology , Contact Tracing , HIV Infections/epidemiology , Hemorrhagic Fever, Ebola/epidemiology , Humans , Pandemics/prevention & control
2.
Sensors (Basel) ; 22(11)2022 Jun 02.
Article in English | MEDLINE | ID: mdl-35684876

ABSTRACT

Due to its significant global impact, both domestic and international efforts are underway to cure the infection and stop the COVID-19 virus from spreading further. In resource-limited environments, overwhelmed healthcare institutions and surveillance systems are struggling to cope with this epidemic, necessitating a specific strategic response. In this study, we looked into the COVID-19 situation and to establish trust, accountability, and transparency, we employed blockchain's immutable and tamper-proof properties. We offered a smart contract (SC)-based solution (Block-HPCT) that has been successfully tested to preserve a digital health passport (DHP) for vaccine recipients; also, for contact tracing (CT) we employed proof of location concept, which aids in a swift and credible response directly from the appropriate healthcare authorities. To connect on-chain and off-chain data, trusted and registered oracles were integrated and to provide a double layer of security along with symmetric key encryption; both Interplanetary File System (IPFS) and Hyperledger Fabric were merged as storage center. We also provided a full description of the suggested solution's system design, implementation, experiment results, and evaluation (privacy and cost analysis). As per the findings, the suggested approach performed satisfactorily across all significant assessment criteria, implying that it can lead the way for practical implementations and also can be used for similar types of situations where contact tracing of infectious can be crucial.


Subject(s)
Blockchain , COVID-19 , Communicable Diseases , COVID-19/prevention & control , Contact Tracing/methods , Humans , Privacy
3.
Front Public Health ; 10: 847184, 2022.
Article in English | MEDLINE | ID: mdl-35685757

ABSTRACT

COVID-19 contact-tracing applications (CTAs) offer enormous potential to mitigate the surge of positive coronavirus cases, thus helping stakeholders to monitor high-risk areas. The Kingdom of Saudi Arabia (KSA) is among the countries that have developed a CTA known as the Tawakkalna application, to manage the spread of COVID-19. Thus, this study aimed to examine and predict the factors affecting the adoption of Tawakkalna CTA. An integrated model which comprises the technology acceptance model (TAM), privacy calculus theory (PCT), and task-technology fit (TTF) model was hypothesized. The model is used to understand better behavioral intention toward using the Tawakkalna mobile CTA. This study performed structural equation modeling (SEM) analysis as well as artificial neural network (ANN) analysis to validate the model, using survey data from 309 users of CTAs in the Kingdom of Saudi Arabia. The findings revealed that perceived ease of use and usefulness has positively and significantly impacted the behavioral intention of Tawakkalna mobile CTA. Similarly, task features and mobility positively and significantly influence task-technology fit, and significantly affect the behavioral intention of the CTA. However, the privacy risk, social concerns, and perceived benefits of social interaction are not significant factors. The findings provide adequate knowledge of the relative impact of key predictors of the behavioral intention of the Tawakkalna contact-tracing app.


Subject(s)
COVID-19 , Mobile Applications , Contact Tracing , Humans , Privacy , Surveys and Questionnaires
4.
Can Fam Physician ; 68(6): e182-e189, 2022 Jun.
Article in English | MEDLINE | ID: mdl-35701191

ABSTRACT

OBJECTIVE: To explore Canadian FPs' experiences with, perceived barriers to, and perceived facilitators of FP-initiated partner notification (PN) for HIV and other sexually transmitted infections (STIs), as well as to inform the development of tools that might enhance this work. DESIGN: Online survey. SETTING: British Columbia. PARTICIPANTS: A total of 146 FPs recruited through the Divisions of Family Practice community-based networks of FPs throughout the province. MAIN OUTCOME MEASURES: Family physicians' current STI and PN practices, opinions regarding FP-initiated PN, perceived barriers to and facilitators of FP-initiated PN, and preferred PN resources. RESULTS: More than 90% of FPs had diagnosed an STI within the past year, and most (60.3% to 96.6%, depending on the STI) told patients to inform their partners. Two-thirds (66.4%) felt that PN should not be done by FPs, and fewer than 10% reported contacting partners. Reported barriers included inaccurate or incomplete lists of partners (67.1%), poor compensation (54.1%), and insufficient time (54.1%). Facilitators chosen by respondents included another health professional assigned to follow up with PN (77.4%) and improved remuneration (74.7%). Electronic PN tools directed at patients (eg, PN slips) were favoured over resources directed at providers. CONCLUSION: Family physicians regularly manage STIs and currently take part in PN primarily through educating index cases. However, most do not feel that PN should be conducted by FPs, and most believe that FP-initiated PN would require additional personnel, remuneration, and legal guidance.


Subject(s)
Contact Tracing , Sexually Transmitted Diseases , British Columbia , Humans , Physicians, Family , Sexual Partners , Sexually Transmitted Diseases/diagnosis , Sexually Transmitted Diseases/epidemiology , Sexually Transmitted Diseases/prevention & control
5.
J R Soc Interface ; 19(191): 20220128, 2022 Jun.
Article in English | MEDLINE | ID: mdl-35702865

ABSTRACT

We present a stochastic epidemic model to study the effect of various preventive measures, such as uniform reduction of contacts and transmission, vaccination, isolation, screening and contact tracing, on a disease outbreak in a homogeneously mixing community. The model is based on an infectivity process, which we define through stochastic contact and infectiousness processes, so that each individual has an independent infectivity profile. In particular, we monitor variations of the reproduction number and of the distribution of generation times. We show that some interventions, i.e. uniform reduction and vaccination, affect the former while leaving the latter unchanged, whereas other interventions, i.e. isolation, screening and contact tracing, affect both quantities. We provide a theoretical analysis of the variation of these quantities, and we show that, in practice, the variation of the generation time distribution can be significant and that it can cause biases in the estimation of reproduction numbers. The framework, because of its general nature, captures the properties of many infectious diseases, but particular emphasis is on COVID-19, for which numerical results are provided.


Subject(s)
COVID-19 , Epidemics , COVID-19/epidemiology , COVID-19/prevention & control , Contact Tracing/methods , Disease Outbreaks/prevention & control , Epidemics/prevention & control , Humans
6.
J R Soc Interface ; 19(191): 20220173, 2022 Jun.
Article in English | MEDLINE | ID: mdl-35702867

ABSTRACT

Inferring the relative strength (i.e. the ratio of reproduction numbers) and relative speed (i.e. the difference between growth rates) of new SARS-CoV-2 variants is critical to predicting and controlling the course of the current pandemic. Analyses of new variants have primarily focused on characterizing changes in the proportion of new variants, implicitly or explicitly assuming that the relative speed remains fixed over the course of an invasion. We use a generation-interval-based framework to challenge this assumption and illustrate how relative strength and speed change over time under two idealized interventions: a constant-strength intervention like idealized vaccination or social distancing, which reduces transmission rates by a constant proportion, and a constant-speed intervention like idealized contact tracing, which isolates infected individuals at a constant rate. In general, constant-strength interventions change the relative speed of a new variant, while constant-speed interventions change its relative strength. Differences in the generation-interval distributions between variants can exaggerate these changes and modify the effectiveness of interventions. Finally, neglecting differences in generation-interval distributions can bias estimates of relative strength.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/epidemiology , COVID-19/prevention & control , Contact Tracing , Humans , Pandemics/prevention & control , SARS-CoV-2/genetics
7.
PLoS One ; 17(6): e0268586, 2022.
Article in English | MEDLINE | ID: mdl-35687566

ABSTRACT

Contact tracing is a key component of successful management of COVID-19. Contacts of infected individuals are asked to quarantine, which can significantly slow down (or prevent) community spread. Contact tracing is particularly effective when infections are detected quickly, when contacts are traced with high probability, when the initial number of cases is low, and when social distancing and border restrictions are in place. However, the magnitude of the individual contribution of these factors in reducing epidemic spread and the impact of population immunity (due to either previous infection or vaccination), in determining contact tracing outputs is not fully understood. We present a delayed differential equation model to investigate how the immunity status and the relaxation of social distancing requirements affect contact tracing practices. We investigate how the minimal contact tracing efficiency required to keep an outbreak under control depends on the contact rate and on the proportion of immune individuals. Additionally, we consider how delays in outbreak detection and increased case importation rates affect the number of contacts to be traced daily. We show that in communities that have reached a certain immunity status, a lower contact tracing efficiency is required to avoid a major outbreak, and delayed outbreak detection and relaxation of border restrictions do not lead to a significantly higher risk of overwhelming contact tracing. We find that investing in testing programs, rather than increasing the contact tracing capacity, has a larger impact in determining whether an outbreak will be controllable. This is because early detection activates contact tracing, which will slow, and eventually reverse exponential growth, while the contact tracing capacity is a threshold that will easily become overwhelmed if exponential growth is not curbed. Finally, we evaluate quarantine effectiveness in relation to the immunity status of the population and for different viral variants. We show that quarantine effectiveness decreases with increasing proportion of immune individuals, and increases in the presence of more transmissible variants. These results suggest that a cost-effective approach is to establish different quarantine rules for immune and nonimmune individuals, where rules should depend on viral transmissibility after vaccination or infection. Altogether, our study provides quantitative information for contact tracing downsizing in vaccinated populations or in populations that have already experienced large community outbreaks, to guide COVID-19 exit strategies.


Subject(s)
COVID-19 , Contact Tracing , COVID-19/epidemiology , COVID-19/prevention & control , Contact Tracing/methods , Disease Outbreaks/prevention & control , Humans , Quarantine , SARS-CoV-2
8.
Stud Health Technol Inform ; 290: 1078-1079, 2022 Jun 06.
Article in English | MEDLINE | ID: mdl-35673214

ABSTRACT

Partner Notification (PN) processes are typically part of wider combination prevention efforts and focus on the notification of sexual partners to prevent Sexually Transmitted Infections (STIs), including Human Immunodeficiency Viruses and viral hepatitis. We present a free, voluntary, anonymous and GDPR-compliant Partner Notification service that offers enhanced security and privacy through a web and mobile application via a unique random codes.


Subject(s)
HIV Infections , Sexually Transmitted Diseases , Contact Tracing , HIV Infections/prevention & control , Humans , Privacy , Sexual Partners , Sexually Transmitted Diseases/prevention & control
9.
PLoS One ; 17(6): e0269458, 2022.
Article in English | MEDLINE | ID: mdl-35679290

ABSTRACT

BACKGROUND: Ethiopia has been responding to the COVID-19 pandemic through a combination of interventions, including non-pharmaceutical interventions, quarantine, testing, isolation, contact tracing, and clinical management. Estimating the resources consumed for COVID-19 prevention and control could inform efficient decision-making for epidemic/pandemic-prone diseases in the future. This study aims to estimate the unit cost of COVID-19 sample collection, laboratory diagnosis, and contact tracing in Addis Ababa, Ethiopia. METHODS: Primary and secondary data were collected to estimate the costs of COVID-19 sample collection, diagnosis, and contact tracing. A healthcare system perspective was used. We used a combination of micro-costing (bottom-up) and top-down approaches to estimate resources consumed and the unit costs of the interventions. We used available cost and outcome data between May and December 2020. The costs were classified into capital and recurrent inputs to estimate unit and total costs. We identified the cost drivers of the interventions. We reported the cost for the following outcome measures: (1) cost per sample collected, (2) cost per laboratory diagnosis, (3) cost per sample collected and laboratory diagnosis, (4) cost per contact traced, and (5) cost per COVID-19 positive test identified. We conducted one-way sensitivity analysis by varying the input parameters. All costs were reported in US dollars (USD). RESULTS: The unit cost per sample collected was USD 1.33. The unit cost of tracing a contact of an index case was USD 0.66. The unit cost of COVID-19 diagnosis, excluding the cost for sample collection was USD 3.91. The unit cost of sample collection per COVID-19 positive individual was USD 11.63. The unit cost for COVID-19 positive test through contact tracing was USD 54.00. The unit cost COVID-19 DNA PCR diagnosis for identifying COVID-19 positive individuals, excluding the sample collection and transport cost, was USD 37.70. The cost per COVID-19 positive case identified was USD 49.33 including both sample collection and laboratory diagnosis costs. Among the cost drivers, personnel cost (salary and food cost) takes the highest share for all interventions, ranging from 51-76% of the total cost. CONCLUSION: The costs of sample collection, diagnosis, and contact tracing for COVID-19 were high given the low per capita health expenditure in Ethiopia and other low-income settings. Since the personnel cost accounts for the highest cost, decision-makers should focus on minimizing this cost when faced with pandemic-prone diseases by strengthening the health system and using digital platforms. The findings of this study can help decision-makers prioritize and allocate resources for effective public health emergency response.


Subject(s)
COVID-19 , COVID-19/diagnosis , COVID-19/epidemiology , COVID-19 Testing , Contact Tracing , Ethiopia/epidemiology , Humans , Pandemics/prevention & control
10.
Front Public Health ; 10: 879340, 2022.
Article in English | MEDLINE | ID: mdl-35712301

ABSTRACT

Background: Due to the continual recurrence of COVID-19 in urban areas, it is important to know more about the evolution of the epidemic within this setting to mitigate the risk of the situation getting worse. As the virus spreads through human society, the social networks of confirmed cases can provide us with crucial new insights on this question. Methods: Based on the epidemiological reports of 235 COVID-19 cases in Nanjing, we constructed a social contact network for the epidemic. By analyzing the structure of this network, we explored the transmission characteristics of the epidemic, to provide evidence-based explanations for its transmission. Results: In our constructed transmission network, more than half (95/165, 57.58%) of patients were found not to have transmitted the infection, with only 15 (9.10%) source patients accounting for more than a third of the contagion (60, 36.36%), suggesting that the transmission of COVID-19 varies per individuals. Patients in the 31 to 50 age group were the main source of infectious clusters, with females playing a more active role in passing on the infection. Network component analysis identified nine components with disproportionate concentrations of influential patients, accounting for 49.09% (81) of the patients and 59.09% (78) of epidemiological network contacts. Family aggregation may favor disease transmission, and parenthood is the relationship with the highest infection risk within the family cluster. In addition, some specific public places, such as chess and card parlors, were found to be notable hotspots for community infection. Conclusion: This study presents the evolution of the urban epidemic from the perspective of individual-level and socially interactive processes. This real-world evidence can help to increase public awareness of the epidemic, formulate countermeasures, and allocate limited public health resources for urban management.


Subject(s)
COVID-19 , Epidemics , COVID-19/epidemiology , Contact Tracing , Female , Humans , Public Health , Social Networking
11.
Proc Natl Acad Sci U S A ; 119(26): e2112182119, 2022 Jun 28.
Article in English | MEDLINE | ID: mdl-35696558

ABSTRACT

Detailed characterization of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission across different settings can help design less disruptive interventions. We used real-time, privacy-enhanced mobility data in the New York City, NY and Seattle, WA metropolitan areas to build a detailed agent-based model of SARS-CoV-2 infection to estimate the where, when, and magnitude of transmission events during the pandemic's first wave. We estimate that only 18% of individuals produce most infections (80%), with about 10% of events that can be considered superspreading events (SSEs). Although mass gatherings present an important risk for SSEs, we estimate that the bulk of transmission occurred in smaller events in settings like workplaces, grocery stores, or food venues. The places most important for transmission change during the pandemic and are different across cities, signaling the large underlying behavioral component underneath them. Our modeling complements case studies and epidemiological data and indicates that real-time tracking of transmission events could help evaluate and define targeted mitigation policies.


Subject(s)
COVID-19 , Contact Tracing , SARS-CoV-2 , COVID-19/transmission , Humans , New York City/epidemiology , Pandemics , Population Dynamics , Time Factors , Washington/epidemiology
12.
Rev Saude Publica ; 56: 53, 2022.
Article in English, Portuguese | MEDLINE | ID: mdl-35703607

ABSTRACT

OBJECTIVE: To evaluate the performance of tuberculosis control in Brazilian municipalities. METHODS: This is an ecological study on Brazilian municipalities that notified at least four new cases of tuberculosis, with a minimum of one new case of pulmonary tuberculosis between 2015 and 2018. The municipalities were stratified according to the population in < 50 thousand, 50-100 thousand, 100-300 thousand, and > 300 thousand inhabitants, and the k-means method was used to group them within each population range according to the performance of six indicators of the disease. RESULTS: A total of 2,845 Brazilian municipalities were included, comprising 98.5% (208,007/211,174) of new tuberculosis cases in the period. For each population range, three groups (A, B, and C) of municipalities were identified according to the performance of the indicators: A, the most satisfactory; B, the intermediates; and C, the least satisfactory. Municipalities in group A with < 100 thousand inhabitants presented results above the targets for laboratory confirmation (≥ 72%), abandonment (≤ 5%), and cure (≥ 90%), and comprised 2% of new cases of the disease. Conversely, municipalities of groups B and C presented at least five indicators with results below the targets - HIV testing (< 100%), contact investigation (< 90%), directly observed therapy (< 90%), abandonment (> 5%), and cure (< 90%) -, and corresponded to 66.7% of new cases of tuberculosis. In group C of municipalities with > 300 thousand inhabitants, which included 19 of the 27 capitals and 43.1% of new cases of tuberculosis, the lowest percentages of contact investigation (mean = 56.4%) and directly observed therapy (mean = 15.4%) were verified, in addition to high abandonment (mean = 13.9%) and low coverage of primary health care (mean = 66.0%). CONCLUSIONS: Most new cases of tuberculosis occurred in municipalities with unsatisfactory performance for disease control. Expanding the coverage of primary health care in these places can reduce abandonment and increase the contact investigation and directly observed therapy.


Subject(s)
Tuberculosis, Pulmonary , Tuberculosis , Brazil/epidemiology , Cities , Contact Tracing , Humans , Tuberculosis/diagnosis , Tuberculosis/epidemiology , Tuberculosis/prevention & control , Tuberculosis, Pulmonary/diagnosis , Tuberculosis, Pulmonary/epidemiology , Tuberculosis, Pulmonary/prevention & control
13.
Internet resource in Portuguese | LIS -Health Information Locator | ID: lis-48796

ABSTRACT

Diante da ocorrência de casos de varíola do macaco em alguns países dentro e fora da Região das Américas, a Organização Pan-Americana da Saúde/Organização Mundial da Saúde (OPAS/OMS) compartilha com seus Estados-Membros uma série de considerações em relação a identificação de casos, isolamento, identificação e acompanhamento de contatos, manejo clínico, e prevenção e controle de infecção relacionada à atenção a saúde. Também oferece orientações sobre tratamentos disponíveis e vacinas


Subject(s)
Monkeypox/epidemiology , Emergency Watch , Monkeypox/diagnosis , Contact Tracing
14.
Article in English | MEDLINE | ID: mdl-35565040

ABSTRACT

COVID-19 contact-tracing mobile applications have been some of the most important tools during the COVID-19 pandemic. One preventive measure that has been incorporated to help reduce the virus spread is the strict implementation of utilizing a COVID-19 tracing application, such as the MorChana mobile application of Thailand. This study aimed to evaluate the factors affecting the actual usage of the MorChana mobile application. Through the integration of Protection Motivation Theory (PMT) and Unified Theory of Acceptance and Use of Technology (UTAUT2), latent variables such as performance expectancy (PE), effort expectancy (EE), social influence (SI), facilitating conditions (FC), hedonic motivation (HM), habit (HB), perceived risk (PCR), self-efficacy (SEF), privacy (PR), trust (TR), and understanding COVID-19 (U) were considered to measure the intention to use MorChana (IU) and the actual usage (AU) of the mobile application. This study considered 907 anonymous participants who voluntarily answered an online self-administered survey collected via convenience sampling. The results show that IU presented the highest significant effect on AU, followed by HB, HM, PR, FC, U, SEF, PE, EE, TR, and SI. This is evident due to the strict implementation of using mobile applications upon entering any area of the vicinity. Moreover, PCR was not seen to be a significant latent factor affecting AU. This study is the first to have evaluated mobile contact tracing in Thailand. The integrated framework can be applied and extended to determine factors affecting COVID-19 tracing applications in other countries. Moreover, the findings of this study could be applied to other health-related mobile applications worldwide.


Subject(s)
COVID-19 , Mobile Applications , COVID-19/epidemiology , COVID-19/prevention & control , Contact Tracing/methods , Humans , Pandemics , Risk Assessment , Thailand/epidemiology
15.
J Pak Med Assoc ; 72(4): 707-713, 2022 Apr.
Article in English | MEDLINE | ID: mdl-35614606

ABSTRACT

OBJECTIVE: To determine risk-group-specific rate of becoming COVID-19-positive among healthcare workers having had contact with COVID-19 cases. METHODS: The retrospective cohort study was conducted at the Ege University Hospital, Bornova, Turkey, and comprised all healthcare workers who had come into contact with COVID-19 cases between March 11 and May 31, 2020. The contacts were classified as low-risk, medium-risk and high-risk using the guidelines of the Turkish Ministry of Health. The outcome measures were the incidence of infection among contacts and the incubation period and serial interval among the new cases. Data was analysed using SPSS 23. RESULTS: Of the 845 cases, 312(37%) had high risk, 263(31%) medium and 270(32%) low. Overall, there were 490(58%) females, 355(41%) males, 565(67%) aged <40 years, and 277(33%) aged >40 years. Of the total, 27(3.20%) healthcare workers tested COVID-19-positive and distribution among the risk-based groups was significant (p=0.037). There was a significantly increased risk of incidence among repeated contacts, no mask use, and the source being a colleague (p<0.05). CONCLUSIONS: The detection of high-risk contacts was found to be important for controlling COVID-19 infection in a hospital setting.


Subject(s)
COVID-19 , COVID-19/epidemiology , Contact Tracing , Female , Health Personnel , Hospitals, University , Humans , Male , Personnel, Hospital , Retrospective Studies , SARS-CoV-2
16.
Article in English | MEDLINE | ID: mdl-35627647

ABSTRACT

The continuous rise of the COVID-19 Omicron cases despite the vaccination program available has been progressing worldwide. To mitigate the COVID-19 contraction, different contact tracing applications have been utilized such as Thai Chana from Thailand. This study aimed to predict factors affecting the perceived usability of Thai Chana by integrating the Protection Motivation Theory and Technology Acceptance Theory considering the System Usability Scale, utilizing deep learning neural network and random forest classifier. A total of 800 respondents were collected through convenience sampling to measure different factors such as understanding COVID-19, perceived severity, perceived vulnerability, perceived ease of use, perceived usefulness, attitude towards using, intention to use, actual system use, and perceived usability. In total, 97.32% of the deep learning neural network showed that understanding COVID-19 presented the most significant factor affecting perceived usability. In addition, random forest classifier produced a 92% accuracy with a 0.00 standard deviation indicating that understanding COVID-19 and perceived vulnerability led to a very high perceived usability while perceived severity and perceived ease of use also led to a high perceived usability. The findings of this study could be considered by the government to promote the usage of contact tracing applications even in other countries. Finally, deep learning neural network and random forest classifier as machine learning algorithms may be utilized for predicting factors affecting human behavior in technology or system acceptance worldwide.


Subject(s)
COVID-19 , Deep Learning , Mobile Applications , COVID-19/epidemiology , COVID-19/prevention & control , Contact Tracing , Humans , Neural Networks, Computer , Thailand/epidemiology
17.
PLoS Comput Biol ; 18(5): e1008800, 2022 05.
Article in English | MEDLINE | ID: mdl-35604952

ABSTRACT

The fraction of cases reported, known as 'reporting', is a key performance indicator in an outbreak response, and an essential factor to consider when modelling epidemics and assessing their impact on populations. Unfortunately, its estimation is inherently difficult, as it relates to the part of an epidemic which is, by definition, not observed. We introduce a simple statistical method for estimating reporting, initially developed for the response to Ebola in Eastern Democratic Republic of the Congo (DRC), 2018-2020. This approach uses transmission chain data typically gathered through case investigation and contact tracing, and uses the proportion of investigated cases with a known, reported infector as a proxy for reporting. Using simulated epidemics, we study how this method performs for different outbreak sizes and reporting levels. Results suggest that our method has low bias, reasonable precision, and despite sub-optimal coverage, usually provides estimates within close range (5-10%) of the true value. Being fast and simple, this method could be useful for estimating reporting in real-time in settings where person-to-person transmission is the main driver of the epidemic, and where case investigation is routinely performed as part of surveillance and contact tracing activities.


Subject(s)
Epidemics , Hemorrhagic Fever, Ebola , Contact Tracing , Democratic Republic of the Congo/epidemiology , Disease Outbreaks , Hemorrhagic Fever, Ebola/epidemiology , Humans
18.
Article in English | MEDLINE | ID: mdl-35627870

ABSTRACT

We aimed to elucidate the range of the incubation period in patients infected with the SARS-CoV-2 Omicron variant in comparison with the Alpha variant. Contact tracing data from three Japanese public health centers (total residents, 1.06 million) collected following the guidelines of the Infectious Diseases Control Law were reviewed for 1589 PCR-confirmed COVID-19 cases diagnosed in January 2022. We identified 77 eligible symptomatic patients for whom the date and setting of transmission were known, in the absence of any other probable routes of transmission. The observed incubation period was 3.03 ± 1.35 days (mean ± SDM). In the log-normal distribution, 5th, 50th and 95th percentile values were 1.3 days (95% CI: 1.0-1.6), 2.8 days (2.5-3.1) and 5.8 days (4.8-7.5), significantly shorter than among the 51 patients with the Alpha variant diagnosed in April and May in 2021 (4.94 days ± 2.19, 2.1 days (1.5-2.7), 4.5 days (4.0-5.1) and 9.6 days (7.4-13.0), p < 0.001). As this incubation period, mainly of sublineage BA.1, is even shorter than that in the Delta variant, it is thought to partially explain the variant replacement occurring in late 2021 to early 2022 in many countries.


Subject(s)
COVID-19 , Infectious Disease Incubation Period , SARS-CoV-2 , COVID-19/epidemiology , Contact Tracing , Humans , Japan/epidemiology , SARS-CoV-2/genetics , SARS-CoV-2/physiology
19.
J Urban Health ; 99(3): 582-593, 2022 Jun.
Article in English | MEDLINE | ID: mdl-35641716

ABSTRACT

To examine how sociodemographic characteristics and non-pharmaceutical interventions affect the transmission of COVID-19, we analyze patient profiles and contact tracing data from almost all cases in an outbreak in Shijiazhuang, China, from January to February 2021. Because of universal testing and digital tracing, the data are of high quality. Results from negative binomial models indicate that the counts of close contacts and secondary infections vary with the cases' age and occupation. Notably, cases under age 18 are causing an increased infection rate among their close contacts and leading to more within-neighborhood secondary infections than adults aged 18-49. Also, county-wide interventions and lockdown are found to be effective at containing the spread of COVID-19. These measures can reduce the number of close contacts that each case has and largely restrict the remaining infections to the case's neighborhood. These results suggest that transmission risks of COVID-19 are associated with the case's sociodemographic characteristics and can be reduced with interventions at the county level. Implications on mitigation measures and reopening plans are discussed.


Subject(s)
COVID-19 , Coinfection , Adult , China/epidemiology , Coinfection/epidemiology , Communicable Disease Control/methods , Contact Tracing/methods , Humans , Policy , SARS-CoV-2
20.
Epidemics ; 39: 100569, 2022 Jun.
Article in English | MEDLINE | ID: mdl-35597098

ABSTRACT

The effort for combating the COVID-19 pandemic around the world has resulted in a huge amount of data, e.g., from testing, contact tracing, modelling, treatment, vaccine trials, and more. In addition to numerous challenges in epidemiology, healthcare, biosciences, and social sciences, there has been an urgent need to develop and provide visualisation and visual analytics (VIS) capacities to support emergency responses under difficult operational conditions. In this paper, we report the experience of a group of VIS volunteers who have been working in a large research and development consortium and providing VIS support to various observational, analytical, model-developmental, and disseminative tasks. In particular, we describe our approaches to the challenges that we have encountered in requirements analysis, data acquisition, visual design, software design, system development, team organisation, and resource planning. By reflecting on our experience, we propose a set of recommendations as the first step towards a methodology for developing and providing rapid VIS capacities to support emergency responses.


Subject(s)
COVID-19 , COVID-19/epidemiology , Contact Tracing , Humans , Pandemics
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