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Potential false-positive rate among the 'asymptomatic infected individuals' in close contacts of COVID-19 patients

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Potential false-positive rate among the 'asymptomatic infected individuals' in close contacts of COVID-19 patients

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Abstract

Objective: As the prevention and control of COVID-19continues to advance, the active nucleic acid test screening in the close contacts of the patients has been carrying out in many parts of China. However, the false-positive rate of positive results in the screening has not been reported up to now. But to clearify the false-positive rate during screening is important in COVID-19 control and prevention. Methods: Point values and reasonable ranges of the indicators which impact the false-positive rate of positive results were estimated based on the information available to us at present. The false-positive rate of positive results in the active screening was deduced, and univariate and multivariate-probabilistic sensitivity analyses were performed to understand the robustness of the findings. Results: When the infection rate of the close contacts and the sensitivity and specificity of reported results were taken as the point estimates, the positive predictive value of the active screening was only 19.67%, in contrast, the false-positive rate of positive results was 80.33%. The multivariate-probabilistic sensitivity analysis results supported the base-case findings, with a 75% probability for the false-positive rate of positive results over 47%. Conclusions: In the close contacts of COVID-19 patients, nearly half or even more of the 'asymptomatic infected individuals' reported in the active nucleic acid test screening might be false positives.

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... In an initial application of this test protocol in Bavaria, Germany, 60.7% unspecific signals were detected, but could be reduced to 5% and lower using different RT-PCR systems (Konrad et al. 2020). A Chinese validation study of the SARS-CoV-2 tests used in China revealed a false-positive rate of almost 50% or higher (Zhuang et al. 2020) -however, the study was retracted for unknown reasons soon after ahead-of-print publication. In clinical practice, false negative signals can be introduced by sample contamination and cross-reactions with other nucleic acids if the primer pairs selected are not highly specific for the target nucleic acid sequence. ...
... We found that for plausible assumptions about v and test sensitivities, positive tests would only provide weak to moderate evidence for the hypothesis that the symptoms in a given patient are caused solely be SARS-CoV-2 unless the tests have a high specificity. Unfortunately, the latter are currently unknown and may be insufficient (Zhuang et al. 2020). ...
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We investigate the epistemological consequences of a positive SARS-CoV-2 test for two relevant hypotheses: (i) V is the hypothesis that an individual has been infected with SARS-CoV-2; (ii) C is the hypothesis that SARS-CoV-2 is the sole cause of flu-like symptoms in a given patient. We ask two fundamental epistemological questions regarding each hypothesis: First, given a positive SARS-CoV-2 test, what should we believe about the hypothesis and to what degree? Second, how much evidence does a positive test provide for a hypothesis against its negation? We respond to each question within a formal Bayesian framework. We construe degree of confirmation as the difference between the posterior probability of the hypothesis and its prior, and the strength of evidence for a hypothesis against its alternative in terms of their likelihood ratio. We find that for realistic assumptions about the base rate of infected individuals, P(V)≲20%, positive tests having low specificity (75%) would not raise the posterior probability for V to more than 50%. Furthermore, if the test specificity is less than 88.1%, even a positive test having 95% sensitivity would only yield weak to moderate evidence for V against ¬V. We also find that in plausible scenarios, positive tests would only provide weak to moderate evidence for C unless the tests have a high specificity. One has thus to be careful in ascribing the symptoms or death of a positively tested patient to SARS-CoV-2, if the possibility exists that the disease has been caused by another pathogen.
... The sensitivity rate is not clear, but is estimated to be around 66-80% [59]. Test validity in asymptomatic individuals who have been in close contact with symptomatic persons is even less clear; the rate of positivity could reach 50% without any evidence of symptoms or proven infection [60]. ...
... In one study, the time period from symptom onset to initial CT scan was evaluated and the authors found that 56% of patients who presented symptoms within 2 days had normal CT images [64]. CT sensitivity seems to be high in patients with positive RT-PCR (86-97% in different case studies) [60] and lower in patients with only constitutional and nonrespiratory symptoms (about 50%) [63]. ...
Article
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... COVID-19 is an RNA virus and can be amplified and detected by Reverse Transcription PCR (RT-PCR) where the RNA is converted to a complementary DNA and the patterns of sequence of the DNA is then identified. Despite its global acceptance and usability, NAAT demonstrates limitations in form of high cases of false negatives during tests of COVID-19 [27]. In addition to the study made by [27], other reports from China on COVID-19 showed that 41% of tested cases showed false negatives. ...
... Despite its global acceptance and usability, NAAT demonstrates limitations in form of high cases of false negatives during tests of COVID-19 [27]. In addition to the study made by [27], other reports from China on COVID-19 showed that 41% of tested cases showed false negatives. In spite of the alarming false negatives rate showed by NAAT, it remains the standard technique for diagnosing COVID-19 to date. ...
Article
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... In addition, strategies to test for anosmia were clinically tested according to prior work by Russell (7) and Lechien (8). 9. Establishment of isolation facilities and a "traffic light zone concept": According to rising infection rates, one (formerly open) ward was transferred to an "isolation unit" with 12 rooms for the treatment of COVID-19positive patients with psychiatric diseases. ...
... The "green zone" was labeled as "sensitive" due to the "patients at risk" treated there (e.g., elderly patients in geriatrics), the "yellow zone" consisted of the "regular patients" and the "red zone" was formed by the isolation units described already above. tests are available as established lab-tests to confirm the infection in an individual, but also these tests have a considerably high false-positive and false-negative risk (9). Moreover, the availability of these tests was limited at the start of the pandemic, resulting in long delays between testing and information about results. ...
Article
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The pandemic spread of the corona virus SARS-CoV-2 has even-handedly shattered national and international health systems and economies almost in an instant. As numbers of infections and COVID-19–related deaths rise from day to day, fears and uncertainties on how to deal with this unknown threat are extremely present both for individuals and societies as a whole. In this manuscript, we aim to exemplarily describe the bullet points concerning (a) the internal risk management, (b) the organizational and structural changes, and (c) the communicational strategies applied in a Psychiatric University Hospital in the Southern part of Germany. The authors are well aware about the fact that almost none of these considerations may be considered as evidence-based at the moment. However, the authors trust that these reflections and experiences may be useful as an orientation for similar risk constellations in other afflicted countries due to the temporal delay of the pandemic course.
... Furthermore, researchers working on other important diseases might feel that their work also deserves OA status, similar to COVID-19-related research, as well as fair peer review and editorial handling. 7 Separately, and unrelated to the retracted Mehra et al. (2020a, b) papers, Zhuang et al. (2020) was withdrawn (i.e., retracted) due to public criticism, and the public file was deleted. Despite this, the paper and its abstract are still listed at ResearchGate, 8 but the paper is not indicated as retracted, thus inviting academics to cite this paper, which has already accrued 28 citations according to GS. ...
Article
Full-text available
Retractions of COVID-19 literature in both preprints and the peer-reviewed literature serve as a reminder that there are still challenging issues underlying the integrity of the biomedical literature. The risks to academia become larger when such retractions take place in high-ranking biomedical journals. In some cases, retractions result from unreliable or nonexistent data, an issue that could easily be avoided by having open data policies, but there have also been retractions due to oversight in peer review and editorial verification. As COVID-19 continues to affect academics and societies around the world, failures in peer review might also constitute a public health risk. The effectiveness by which COVID-19 literature is corrected, including through retractions, depends on the stringency of measures in place to detect errors and to correct erroneous literature. It also relies on the stringent implementation of open data policies.
... The positive rate in swabs samples varies by sample site [35][36][37][38][39][40] but since data are today controversial it is not possible to accurately assess sensitivity and the diagnostic impact of combining oropharyngeal and nasopharyngeal tests. However, one of the largest studies [37] reported that oropharyngeal swabs detected the SARS-CoV-2 less frequently than nasopharyngeal swabs and should not be used in place of nasopharyngeal swabs, particularly from day 8 of symptom onset. ...
... Further, the number of individuals that tested positive for COVID-19 may be dissuasive in understanding the disease, owing to compromised positive and negative predictive values 32,33 . Falsepositivity in COVID-19 testing 32 may be proving costly, but it can be tolerated for effective epidemic control 19 . ...
Article
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This study analyzed the determinants of morbidity, mortality, and case fatality rate (CFR) of the ongoing pandemic of severe acute respiratory syndrome coronavirus-2 disease 2019 (COVID-19). Data for 210 countries and territories available in public domains were analyzed in relation to mandatory vaccination with Bacille-Calmette-Guerin (BCG), population density, median age of the country population, health care expenditure per capita, life expectancy at birth, healthy life expectancy, literacy rate, per capita gross domestic production adjusted to purchasing power (PPP), burden of tuberculosis (TB), acquired immunodeficiency disease caused by human immunodeficiency virus (HIV-AIDS), malaria, cardiovascular disease (CVD), neoplasm, diabetes, deaths due to energy-protein (food) deficiency (EPD), and per capita government spending on safe water and sanitation. Mandatory BCG vaccination showed a highly significant (p
... It is well established that there are no perfect test kits. [11][12][13][14] There is always a possibility that the test result might be false negative (failing to detect infection among infected) or false positive (showing infection among non-infected). [15][16][17] There is no threat if some false positive cases are referred for confirmation test and kept under isolation but if we fail to cover falsenegative cases then the outcomes can be catastrophic. ...
Article
Full-text available
The COVID-19 pandemic has become a global challenge that has driven nations to take some extreme measures in an attempt to prevent outbreaks and save lives. The scientific communities are trying their best to understand the activities of SARS CoV-2 virus to target effective strategies against it. The whole world is trying its best to contain the infection, Nepal is no exception. Nepal underestimated the likelihood of the COVID 19 outbreak during early January however with the increasing case strong measures have been initiated. Nepal reported 2,099 confirmed cases with 266 recoveries and 8 deaths by June 2, 2020. The focus on social distancing and since the middle of March countrywide lockdown has been taken as a strategy to control the rate of infection but the challenge lies in its continuation. There is also a challenge in extension of testing and other public health intervention. Timely action, testing, tracing, tracking, treating, and togetherness have been seen as the most effective strategies to date. Due to the increasing cases of infection and death, it has triggered disruption to social and mental wellbeing of the global citizens. The confusion and uncertainty rise fueling misinformation, stigma and discrimination which are negatively impacting the prevention strategies adopted by different nations. There is a need for proper communication strategies and community engagement alongside the togetherness of all concerned entities fighting against this wicked virus globally. In light of this global need, this paper aims to provide some insights into the strategies and challenges revolving around COVID-19 prevention and control
... This result gave a possibility of false positive rate of rapid rate. A study showed that the positive predictive value of the active screening was only 19.67%, and the false-positive rate was 80.33%, with a 75% probability for the false-positive rate [4]. ...
Article
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Abstract Introduction: COVID19 pandemic forced ministries of health across the world to invent additional measures for control. Active screening is one of these tools. It includes asking questions, taking temperatures and doing rapid test for COVID19 in persons with risk factors. A team of a family medicine physician, lab worker, and administrative is formed. They visit homes with positive cases, making physical exam and COVID19 rapid test to contacts of the cases. Subject and Method: An electronic questionnaire is introduced to family physicians specialists in family medical centers in Baghdad. 99 physicians respond to questionnaire for one week. The questionnaire involved two sections; the 1st one asked if the screening surveillance is necessary for COVID19 control from physician s’ point of view. The 2nd section states the reasons of their opinions. Results: The study included 99 family medical physicians, 56 said yes; screening is necessary to control viral spread while, 43 said no. Discussion and Conclusions: Active screening required intense efforts by medical team with limited resources and hot weather. Rapid test of COVID19 is screening test so it is not detecting all infected people, including some with clinical disease compatible with COVID-19. The study gives a conclusion that there is a controversy about active screening.
... Finally, one preprint shown in the retraction watch search was resubmitted without explanation (Daneshkhah et al. 2020). The characteristics of the remaining seventeen articles are discussed below (Pradhan et al. 2020;Yang et al. 2020;Wang et al. 2020a, b;Bae et al. 2020;Parves 2020;Chu et al. 2020;Mehra et al. 2020a, b;Karami et al. 2020;Davido et al. 2020;Nouvier et al. 2020;Gormley and Ngan 2020;Zhuang et al. 2020;Siyu et al. 2020;Zeng and Zhen 2020;Luo et al. 2020;Tofade and Daftary 2020). ...
Preprint
This letter highlights the characteristics of retracted or withdrawn COVID-19 articles
... Finally, one preprint shown in the retraction watch search was resubmitted without explanation (Daneshkhah et al. 2020). The characteristics of the remaining seventeen articles are discussed below (Pradhan et al. 2020;Yang et al. 2020;Wang et al. 2020a, b;Bae et al. 2020;Parves 2020;Chu et al. 2020;Mehra et al. 2020a, b;Karami et al. 2020;Davido et al. 2020;Nouvier et al. 2020;Gormley and Ngan 2020;Zhuang et al. 2020;Siyu et al. 2020;Zeng and Zhen 2020;Luo et al. 2020;Tofade and Daftary 2020). ...
Article
Full-text available
This letter highlights the characteristics of retracted or withdrawn COVID-19 articles.
... While some of these tests have shown 100% specificity in independent validation studies (Nalla et al. 2020), others have been found to yield a significant percentage of false-negative results. For example, an early validation study of Chinese SARS-CoV-2 RT-qPCR tests revealed a false positive rate of almost 50% or higher (Zhuang et al. 2020) -however, the study was retracted for unknown reasons soon after ahead-ofprint publication. In a German inter-laboratory validation study ("Ringversuch") of many commercially available and in-house RT-qPCR tests, a total of 67 out of 983 SARS-CoV-2-negative samples containing the human coronavirus HCoV 229E were classified as "positive", yielding an average false-positive rate of 6.8% (Zeichhardt and Kammel 2020). ...
Article
Full-text available
We investigate the epistemological consequences of a positive polymerase chain reaction SARS-CoV test for two relevant hypotheses: (i) V is the hypothesis that an individual has been infected with SARS-CoV-2; (ii) C is the hypothesis that SARS-CoV-2 is the cause of flu-like symptoms in a given patient. We ask two fundamental epistemological questions regarding each hypothesis: First, how much confirmation does a positive test lend to each hypothesis? Second, how much evidence does a positive test provide for each hypothesis against its negation? We respond to each question within a formal Bayesian framework. We construe degree of confirmation as the difference between the posterior probability of the hypothesis and its prior, and the strength of evidence for a hypothesis against its alternative in terms of their likelihood ratio. We find that test specificity-and coinfection probabilities when making inferences about C-were key determinants of confirmation and evidence. Tests with < 87% specificity could not provide strong evidence (likelihood ratio > 8) for V against ¬V regardless of sensitivity. Accordingly, low specificity tests could not provide strong evidence in favor of C in all plausible scenarios modeled. We also show how a positive influenza A test disconfirms C and provides weak evidence against C in dependence on the probability that the patient is influenza A infected given that his/her symptoms are not caused by SARS-CoV-2. Our analysis points out some caveats that should be considered when attributing symptoms or death of a positively tested patient to SARS-CoV-2.
... The denominator is the total number of people diagnosed with the disease and it depends on the effort deployed to test the population (that varies among countries and it is the result of different prevention strategies), and on the accuracy of the test, which has been shown to be inaccurate (from the results of a recent study [11], false positives could be at least 50%). With these premises, fatality rate cannot be reliably computed at the moment. ...
Article
This paper shows some views on the mathematical structure of the diffusion of the Coronavirus (COVID-19), often claimed to have a positive exponential structure. However, we find that the exponential growth rate is past the inflection point and that growth is much slower than this implication. It presents conclusions on the future expected outcome of the current situation, not only in terms of diffusion of the disease but also for the hysteria that has been created around it.
... Li et al. (2020a) reported a potentially high false negative rate of RT-PCR testing for SARS-CoV-2 in the 610 hospitalized patients they studied, from whom 241 (39.5%) patients were finally confirmed with COVID-19 with at least one positive RT-PCR test result. In asymptomatic individuals who have been in close contact with symptomatic persons, the rate of positivity could reach 50% without any evidence of symptoms or proven infection (Zhuang et al., 2020). Studies that give the amount of SARS-CoV-2 RNA in clinical specimens by reporting cycle threshold (Ct) values for RT-PCR are limited. ...
Article
Full-text available
Aim There are limited number of studies analyzing viral load in COVID19 patients and any data that compare viral load to chest computerized tomography (CT) severity. This study aims to evaluate the severity of chest CT in reverse transcriptase polymerase chain reaction (RT-PCR) positive patients and factors associated with it. Methodology SARS-CoV-2 RNA was extracted from nasopharyngeal swab samples by using Bio-speedy viral nucleic acid buffer. RT-PCR test was performed with primers and probes targeting the RdRp gene (Bioexen LTD, Turkey) and results were quantified as Cycle threshold (Ct) values. Chest CT of SARS-CoV-2 RNA positive patients (n: 730) in a period between March 22 and May 20, 2020 were evaluated. Total severity score (TSS) of chest CT ranged 0-20 was calculated by summing up degree of acute lung inflammation lesions involvement of each of the five lung lobes. Results Out of the 284 patients that were hospitalized, 27 (9.5%) of them died. In a total of 236 (32.3%) patients, there were no findings in CT and 216 (91.5%) of them were outpatients (median age 35). TSS was significantly higher in hospitalized patients although only 5.3% had severe changes. Ct values were lower among outpatients indicating higher viral load. An inverse relation between viral load and TSS was detected in both groups. CT severity was related with age and older patients had higher TSS (p < 0.01). Conclusion Viral load is not a critical factor for hospitalisation and mortality whereas outpatients have considerable amount of virus in their nasopharynx that makes them contagious to their contacts. Viral load is important to detect early stages of COVID-19 to minimize potential spread, whereas chest CT can help identify cases requiring extensive medical care.
... Li et al. (2020a) reported a potentially high false negative rate of RT-PCR testing for SARS-CoV-2 in the 610 hospitalized patients they studied, from whom 241 (39.5%) patients were finally confirmed with COVID-19 with at least one positive RT-PCR test result. In asymptomatic individuals who have been in close contact with symptomatic persons, the rate of positivity could reach 50% without any evidence of symptoms or proven infection (Zhuang et al., 2020). Studies that give the amount of SARS-CoV-2 RNA in clinical specimens by reporting cycle threshold (Ct) values for RT-PCR are limited. ...
Article
Aim: Studies analyzing viral load in COVID-19 patients and any data that compare viral load with chest computerized tomography (CT) severity are limited. This study aimed to evaluate the severity of chest CT in reverse transcriptase polymerase chain reaction (RT-PCR)-positive patients and factors associated with it. Methodology: SARS-CoV-2 RNA was extracted from nasopharyngeal swab samples by using Bio-speedy viral nucleic acid buffer. The RT-PCR tests were performed with primers and probes targeting the RdRp gene (Bioexen LTD, Turkey) and results were quantified as cycle threshold (Ct) values. Chest CT of SARS-CoV-2 RNA-positive patients (n = 730) in a period from 22 March to 20 May 2020 were evaluated. The total severity score (TSS) of chest CT ranged 0–20 and was calculated by summing up the degree of acute lung inflammation lesion involvement of each of the five lung lobes. Results: Of the 284 patients who were hospitalized, 27 (9.5%) of them died. Of 236 (32.3%) patients, there were no findings on CT and 216 (91.5%) of them were outpatients (median age 35 years). TSS was significantly higher in hospitalized patients; 5.3% had severe changes. Ct values were lower among outpatients, indicating higher viral load. An inverse relation between viral load and TSS was detected in both groups. CT severity was related to age, and older patients had higher TSS (p < 0.01). Conclusion: Viral load was not a critical factor for hospitalization and mortality. Outpatients had considerable amounts of virus in their nasopharynx, which made them contagious to their contacts. Viral load is important in detecting early stages of COVID-19, to minimize potential spread, whereas chest CT can help identify cases requiring extensive medical care.
... So, the rate of sensitivity is predicted to be around 66-80% [37]. One negative result doesn't omit the chances of SARS-CoV-2 infection, mostly in the cases of highly exposed persons just by taking a swab from the nasopharynx, in those cases it is recommended to take the test again or collect the specimen from the deeper region of respiratory tract by bronchoscopy [1,38]. ...
Article
Full-text available
Since 2019, the SARS-CoV-2 pandemic has caused a huge chaos throughout the world and the major threat has been possessed by the immune-compromised individuals involving the cancer patients; their weakened immune response makes them vulnerable and susceptible to the virus. The oncologists as well as their patients are facing many problems for their treatment sessions as they need to postpone their surgery, chemotherapy, or radiotherapy. The approach that could be adopted especially for the cancer patients is the amalgamation of immunotherapy and nanotherapy which can reduce the burden on the healthcare at this peak time of the infection. There is also a need to predict or analyze the data of cancer patients who are at a severe risk of being exposed to an infection in order to reduce the mortality rate. The use of artificial intelligence (AI) could be incorporated where the real time data will be available to the physicians according to the different patient’s clinical characteristics and their past treatments. With this data, it will become easier for them to modify or replace the treatment to increase the efficacy against the infection. The combination of an immunotherapy and nanotherapy will be targeted to treat the cancer patients diagnosed with SARS-CoV-2 and the AI will act as icing on the cake to monitor, predict and analyze the data of the patients to improve the treatment regime for the most vulnerable patients.
... Furthermore, the sensitivity and specificity of GGO for COVID-19 diagnoses were high (85% and 45%, respectively). Similar results were found in other studies, with a high sensitivity of CT in SARS-CoV-2-positive patients (86-97%) [22,32]. ...
Article
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Background and Objectives: During the coronavirus disease 2019 (COVID-19) pandemic, patients with chronic diseases suffering exacerbations have required acute medical care. The purpose of our study was to determine useful criteria for the differentiation of patients with acute clinical syndromes and suspicion of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Materials and Methods: This was an observational retrospective study, conducted in an internal medicine clinic from April to May 2020. We collected clinical, biological, and computed tomography (CT) data on patients with exacerbations of chronic diseases and clinical suspicion of SARS-CoV-2 infection. Patients with an already-positive real-time reverse-transcription polymerase chain reaction (RT-PCR) test for SARS-CoV-2 on presentation at the emergency department were excluded from our study. Results: Of 253 suspected cases, 20 were laboratory-confirmed as having SARS-CoV-2 infection by RT-PCR, whereas COVID-19 diagnosis was ruled out in the remaining 233. Venous thromboembolism (VTE) correlated significantly with COVID-19 diagnosis in suspected patients, while laboratory markers were not significantly different between the two groups. Of the suspected patients, significantly higher percentages of dry cough, fever, myalgias, sore throat, loss of smell and appetite, and ground-glass opacities (GGOs) on CT were found in SARS-CoV-2-positive individuals. Conclusions: The study demonstrated that, until receiving the result of an RT-PCR test for SARS-CoV-2 (usually 12–24 h), association with VTE as a comorbidity, fever, dry cough, and myalgia as clinical features, and GGO on CT are the main markers for the identification of COVID-19 patients among those suspected with acute clinical syndromes. Our results also provide evidence for doctors not to rely solely on biological markers in the case of suspected SARS-CoV-2 infection in patients with exacerbations of chronic diseases. These data are useful for faster decision-making with regard to suspected COVID-19 patients before receiving RT-PCR test results, thus avoiding keeping patients in crowded emergency departments.
... Finally, all the included studies relied on RT-PCR testing; no further investigation using chest computed tomography imaging was performed. The effect of this could be bi-directional and result in either overestimation or underestimation because some cases might have been missed due to false-negative results or some cases might have been included due to false-positive COVID-19 results [38,39]. ...
Article
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The coronavirus disease 2019 (COVID-19) cases could be symptomatic or asymptomatic. We (1) characterized and analyzed data collected from the first cohort of reverse transcriptase polymerase chain reaction (RT-PCR)-confirmed COVID-19 cases reported in the Emirate of Abu Dhabi, United Arab Emirates, according to the symptomatic state, and (2) identified factors associated with the symptomatic state. The association between the symptomatic state and testing positive in three subsequent RT-PCR testing rounds was also quantified. Between February 28 and April 8, 2020, 1,249 cases were reported. Sociodemographic characteristics, working status, travel history, and chronic comorbidities of 791 cases were analyzed according to the symptomatic state (symptomatic or asymptomatic). After the first confirmatory test, the results of three subsequent tests were analyzed. The mean age of the 791 cases was 35.6 ± 12.7 years (range: 1–81). Nearly 57.0% of cases were symptomatic. The two most frequent symptoms were fever (58.0%) and cough (41.0%). Symptomatic cases (mean age 36.3 ± 12.6 years) were significantly older than asymptomatic cases (mean age 34.5 ± 12.7 years). Compared with nonworking populations, working in public places (adjusted odds ratio (aOR), 1.76, 95% confidence interval (95% CI): 1.11–2.80), healthcare settings (aOR, 2.09, 95% CI: 1.01–4.31), or in the aviation and tourism sectors (aOR, 2.24, 95% CI: 1.14–4.40) was independently associated with the symptomatic state. Reporting at least one chronic comorbidity was also associated with symptomatic cases (aOR, 1.76, 95% CI: 1.03–3.01). Compared with asymptomatic cases, symptomatic cases had a prolonged duration of viral shedding and consistent odds of ≥2 positive COVID-19 tests result out of the three subsequent testing rounds. A substantial proportion of the diagnosed COVID-19 cases in the Emirate of Abu Dhabi were asymptomatic. Quarantining asymptomatic cases, implementing prevention measures, and raising awareness among populations working in high-risk settings are warranted.
... The sensitivity levels are not explicit, but are estimated at around 66-80%.The validity of tests in asymptomatic persons in close contact with symptomatic persons is much less clear; the rate of positivity could exceed 50% without symptoms or confirmed infection (Ai et al. 2020). A single negative test does not preclude SARS-CoV-2 infection, especially in highly exposed individuals where the test is performed using a nasopharyngeal swab specimen and at the onset of the infection (Zhuang et al. 2020). Infection severity can be estimated through a standard real-time RT-PCR set-up that usually runs through 35 cycles, meaning that around 35 billion new copies of the viral DNA sections are created from each virus strand present in the sample by the end of the process. ...
Chapter
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Coronavirus disease 2019 (COVID-19) is a highly contagious pathogenic viral infection caused by SARS-Cov-2. Coronavirus seems to have taken a popular role in the twenty-first century. The first instance of COVID-19 which was reported in Hubei province, Wuhan, China, has now spread to the entire world by human-to-human transmission. The World Health Organization (WHO) declared this infectious disease as a pandemic. Currently this pandemic has created a global health crisis. In this chapter, we analysed the epidemiological characteristics, i.e. occurrence, distribution and transmission of disease in different countries, laboratory diagnosis, prevention, control and treatment of COVID-19. The main objective of this chapter is to provide the latest insights over nanotechnology and its implications in the diagnosis, treatment, prevention and control of COVID-19. In this direction, several emerging issues such as optical biosensor nanotechnology, respiratory masks, Nanofibers Membrane Technology, etc. We are in opinion that this chapter will provide useful insights towards understanding the role of nanotechniques to combat COVID-19.
... The rate of sensitivity is reported around 66-80% [53]. The chances of getting positive of an asymptomatic case by close contact of a positive patient are not yet clearly mentioned [54]. ...
Article
Corona virus first reported in the early December, 2019 from Wuhan, a city in Hubei Province in the Republic of China. A novel corona virus is belongs to the Severe acute respiratory syndrome corona virus-2 the same family as SARS-CoV and MERS corona virus. The SARS-Corona virus-2 had similarity with acute respiratory distress syndrome (ARDS), which had also the high mortality during 2002-2003. The corona virus has rapidly spread all over the world and emerged as a deadly disease. The World Health Organization declared this as a public health emergency and a pandemic disease named as corona virus disease-19 (COVID-19). The transmission of virus from human to human causes high rise in death rates around the globe. Acute lungs injury at all stages of life or in some individuals with high-risk was reported earlier shows that, such as old age people or those persons affected with multi-morbidities, this novel virus can cause serious pneumonia like condition, ARDS, followed by multi-organ failure, these factors are the main cause of acute respiratory failure with higher death rates. Affected persons typically show different types of dyspnoea as well as radiological signs. The personal protective equipment (PPE) is highly recommended for wearing at some specific areas. The sign and symptoms of this novel COVID-19 are mainly high fever, mild dry cough, sore throat, headache, fatigue, mild dyspnoea and gastrointestinal issues. To test the presence of novel corona virus, swabs are collected from the nasal, tracheal aspirate and Broncho-alveolar lavage and for the samples testing, Real-time PCR is being used. Computed tomography (CT) results are crucial for the diagnosis and follow-up process. According to Epidemiological studies the people with old age and patients having diseases like hypertension, high blood sugar previously were more susceptible this disease, while children tends to have mild symptoms. In this review, we highlighted the Structural, epidemiological, statistical data, signs and symptoms as well as the treatments and vaccine available for the treatment of this novel corona virus.
... Duplicate publication ---5 [ retraction requested by a scientific journal was retracted due to concerns that the conclusions were based on theory not field epidemiology data and thus further research was needed [68]. ...
Article
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Background Retraction of published research can reduce the dissemination of incorrect or misleading information, but concerns have been raised about the clarity and rigor of the retraction process. Failure to clearly and consistently retract research has several risks, for example discredited or erroneous research may inform health research studies (e.g. clinical trials), policies and practices, potentially rendering these unreliable. Objective To investigate consistency and clarity of research retraction, based on a case study of retracted Covid-19 research. Study design A cross-sectional study of retracted Covid-19 articles reporting empirical research findings, based on searches of Medline, Embase and Scopus on 10 th July and 19 th December 2020. Key results We included 46 retracted Covid-19 articles. The number eligible for inclusion nearly doubled, from 26 to 46, in five months. Most articles (67%) were retracted from scientific journals and the remainder from preprint servers. Key findings: (1) reasons for retraction were not reported in 33% (15/46) of cases; (2) time from publication to retraction could not be determined in 43% (20/46) of cases; (3) More than half (59%) of retracted Covid-19 articles (27/46) remained available as original unmarked electronic documents after retraction (33% as full text and 26% as an abstract only). Sources of articles post-retraction were preprint servers, ResearchGate and, less commonly, websites including PubMed Central and the World Health Organization. A retracted journal article which controversially claimed a link between 5G technology and Covid-19 remains available in its original full text from at least 60 different websites. Conclusions The retraction process is inconsistent and often ambiguous, with more than half of retracted Covid-19 research articles remaining available, unmarked, from a wide range of online sources. There is an urgent need to improve guidance on the retraction process and to extend this to cover preprint servers. We provide structured recommendations to address these concerns and to reduce the risks that arise when retracted research is inappropriately cited.
... Such patients get positive result of SNAT, but have no pneumonia-related features, which leads to negligence in epidemic prevention. They are also infectious with potential to develop positive and typical clinical symptoms [15]. However, how occur the development of asymptomatic patients with positive SNAT remains unclear [16]. ...
Article
Objective: This study was designed to explore the clinical characteristics, outcomes, and related influencing factors for asymptomatic patients with positive Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-Cov-2) nucleic acid test. Methods: Clinical data of 1568 patients with positive SARS-Cov-2 nucleic acid test (SNAT) were collected retrospectively. The patients were assigned to an asymptomatic group and a symptomatic group according to the existence of clinical symptoms when they got positive result in nucleic acid test, and the clinical data of the two groups were analyzed and compared. In addition, the data of asymptomatic patients who showed clinical symptoms later and the results of two-week follow-up after cure were analyzed. Results: Among all enrolled patients, there were 1489 patients with positive symptoms and 79 asymptomatic patients, including 34 patients who developed symptoms during treatment. Logistic analysis revealed that age ≤45 years (OR=2.722, P<0.001), history of diabetes mellitus (OR=0.446, P=0.007), and history of cancer (OR=0.259, P=0.008) were independent factors for asymptomatic presentation in patients with positive SNAT, and age ≥46 years (OR=1.562, P=0.012) and history of hypertension (OR=2.077, P<0.001) were risk factors for the occurrence of clinical symptoms in asymptomatic patients with positive SNAT during hospitalization. During the follow-up after cure, 8 patients got reoccurring positive SNAT result. Conclusion: Asymptomatic patients with positive SNAT are mostly young and middle-aged people, and old age and hypertension are risk factors for the occurrence of positive clinical characteristics in asymptomatic patients.
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Lots of works aim to reveal the driving factors of COVID-19 pandemic trajectory yet ignore the confidence of utilized trajectory data, making consequent results suspicious. Hereby, we proposed a pandemic metric with confidence (PMC) model in the hypothesis of Bernoulli Distribution of nine trajectories reported from 113 countries. Results exhibit the average confidence of trajectories across the global not in excess of 12.1% with the error threshold configuration of 1E-5. In contrast, the 95% high confidence setting also failed to predict the trajectory containing the acceptable error not beyond 1E-3. Thus, a proposed trade-off strategy between two contradictory expections (>50% confidence, <1E-3 error) supports 61% of investigated countries to predict the varying trajectory with confidence beyond 50%. Moreover, PMC model recommend the remanent 39% countries to extend the proportion of populaces in COVID-19 detecting-pool to a suggested-value (>1% of populations), ensuing the average confidence up to 70%.
Article
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rative review, diagnostic tools for COVID-19 diagnosis and their main critical issues were reviewed. The COVID-19 real-timereverse transcriptase-polymerase chain reaction (RT-PCR) test is considered the gold standard test for the qualitative and quan-titative detection of viral nucleic acid. In contrast, tests can be used for epidemiological surveys on specific communities, in-cluding occupational cohorts, but not for clinical diagnosis as a substitute for swab tests. Computed tomography (CT) scanscan be useful for the clinical diagnosis of COVID-19, especially in symptomatic cases. The imaging features of COVID-19 arediverse and depend on the stage of infection after the onset of symptoms. CT sensitivity seems to be higher in patients withpositive RT-PCR. Conventional chest sensitivity shows a lower sensitivity. An important diagnostic screening tool is ultrasounds,whose specificity and sensitivity depend on disease severity, patient weight, and operator skills. Nevertheless, ultrasounds couldbe useful as a screening tool in combination with clinical features and molecular testing to monitor disease progression. Clinical symptoms and non-specific laboratory findings may be useful if used in combination with RT-PCR test and CT-scanning.
Article
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Background: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus and resulting COVID-19 pandemic present important diagnostic challenges. Several diagnostic strategies are available to identify current infection, rule out infection, identify people in need of care escalation, or to test for past infection and immune response. Serology tests to detect the presence of antibodies to SARS-CoV-2 aim to identify previous SARS-CoV-2 infection, and may help to confirm the presence of current infection. Objectives: To assess the diagnostic accuracy of antibody tests to determine if a person presenting in the community or in primary or secondary care has SARS-CoV-2 infection, or has previously had SARS-CoV-2 infection, and the accuracy of antibody tests for use in seroprevalence surveys. Search methods: We undertook electronic searches in the Cochrane COVID-19 Study Register and the COVID-19 Living Evidence Database from the University of Bern, which is updated daily with published articles from PubMed and Embase and with preprints from medRxiv and bioRxiv. In addition, we checked repositories of COVID-19 publications. We did not apply any language restrictions. We conducted searches for this review iteration up to 27 April 2020. Selection criteria: We included test accuracy studies of any design that evaluated antibody tests (including enzyme-linked immunosorbent assays, chemiluminescence immunoassays, and lateral flow assays) in people suspected of current or previous SARS-CoV-2 infection, or where tests were used to screen for infection. We also included studies of people either known to have, or not to have SARS-CoV-2 infection. We included all reference standards to define the presence or absence of SARS-CoV-2 (including reverse transcription polymerase chain reaction tests (RT-PCR) and clinical diagnostic criteria). Data collection and analysis: We assessed possible bias and applicability of the studies using the QUADAS-2 tool. We extracted 2x2 contingency table data and present sensitivity and specificity for each antibody (or combination of antibodies) using paired forest plots. We pooled data using random-effects logistic regression where appropriate, stratifying by time since post-symptom onset. We tabulated available data by test manufacturer. We have presented uncertainty in estimates of sensitivity and specificity using 95% confidence intervals (CIs). Main results: We included 57 publications reporting on a total of 54 study cohorts with 15,976 samples, of which 8526 were from cases of SARS-CoV-2 infection. Studies were conducted in Asia (n = 38), Europe (n = 15), and the USA and China (n = 1). We identified data from 25 commercial tests and numerous in-house assays, a small fraction of the 279 antibody assays listed by the Foundation for Innovative Diagnostics. More than half (n = 28) of the studies included were only available as preprints. We had concerns about risk of bias and applicability. Common issues were use of multi-group designs (n = 29), inclusion of only COVID-19 cases (n = 19), lack of blinding of the index test (n = 49) and reference standard (n = 29), differential verification (n = 22), and the lack of clarity about participant numbers, characteristics and study exclusions (n = 47). Most studies (n = 44) only included people hospitalised due to suspected or confirmed COVID-19 infection. There were no studies exclusively in asymptomatic participants. Two-thirds of the studies (n = 33) defined COVID-19 cases based on RT-PCR results alone, ignoring the potential for false-negative RT-PCR results. We observed evidence of selective publication of study findings through omission of the identity of tests (n = 5). We observed substantial heterogeneity in sensitivities of IgA, IgM and IgG antibodies, or combinations thereof, for results aggregated across different time periods post-symptom onset (range 0% to 100% for all target antibodies). We thus based the main results of the review on the 38 studies that stratified results by time since symptom onset. The numbers of individuals contributing data within each study each week are small and are usually not based on tracking the same groups of patients over time. Pooled results for IgG, IgM, IgA, total antibodies and IgG/IgM all showed low sensitivity during the first week since onset of symptoms (all less than 30.1%), rising in the second week and reaching their highest values in the third week. The combination of IgG/IgM had a sensitivity of 30.1% (95% CI 21.4 to 40.7) for 1 to 7 days, 72.2% (95% CI 63.5 to 79.5) for 8 to 14 days, 91.4% (95% CI 87.0 to 94.4) for 15 to 21 days. Estimates of accuracy beyond three weeks are based on smaller sample sizes and fewer studies. For 21 to 35 days, pooled sensitivities for IgG/IgM were 96.0% (95% CI 90.6 to 98.3). There are insufficient studies to estimate sensitivity of tests beyond 35 days post-symptom onset. Summary specificities (provided in 35 studies) exceeded 98% for all target antibodies with confidence intervals no more than 2 percentage points wide. False-positive results were more common where COVID-19 had been suspected and ruled out, but numbers were small and the difference was within the range expected by chance. Assuming a prevalence of 50%, a value considered possible in healthcare workers who have suffered respiratory symptoms, we would anticipate that 43 (28 to 65) would be missed and 7 (3 to 14) would be falsely positive in 1000 people undergoing IgG/IgM testing at days 15 to 21 post-symptom onset. At a prevalence of 20%, a likely value in surveys in high-risk settings, 17 (11 to 26) would be missed per 1000 people tested and 10 (5 to 22) would be falsely positive. At a lower prevalence of 5%, a likely value in national surveys, 4 (3 to 7) would be missed per 1000 tested, and 12 (6 to 27) would be falsely positive. Analyses showed small differences in sensitivity between assay type, but methodological concerns and sparse data prevent comparisons between test brands. Authors' conclusions: The sensitivity of antibody tests is too low in the first week since symptom onset to have a primary role for the diagnosis of COVID-19, but they may still have a role complementing other testing in individuals presenting later, when RT-PCR tests are negative, or are not done. Antibody tests are likely to have a useful role for detecting previous SARS-CoV-2 infection if used 15 or more days after the onset of symptoms. However, the duration of antibody rises is currently unknown, and we found very little data beyond 35 days post-symptom onset. We are therefore uncertain about the utility of these tests for seroprevalence surveys for public health management purposes. Concerns about high risk of bias and applicability make it likely that the accuracy of tests when used in clinical care will be lower than reported in the included studies. Sensitivity has mainly been evaluated in hospitalised patients, so it is unclear whether the tests are able to detect lower antibody levels likely seen with milder and asymptomatic COVID-19 disease. The design, execution and reporting of studies of the accuracy of COVID-19 tests requires considerable improvement. Studies must report data on sensitivity disaggregated by time since onset of symptoms. COVID-19-positive cases who are RT-PCR-negative should be included as well as those confirmed RT-PCR, in accordance with the World Health Organization (WHO) and China National Health Commission of the People's Republic of China (CDC) case definitions. We were only able to obtain data from a small proportion of available tests, and action is needed to ensure that all results of test evaluations are available in the public domain to prevent selective reporting. This is a fast-moving field and we plan ongoing updates of this living systematic review.
Preprint
Full-text available
Lots of works aim to reveal the driving factors of COVID-19 pandemic trajectory yet ignore the confidence of utilized trajectory data, making consequent results suspicious. Hereby, we proposed a pandemic metric with confidence (PMC) model in the hypothesis of Bernoulli Distribution of nine trajectories reported from 113 countries. Results exhibit the average confidence of trajectories across the global not in excess of 12.1% with the error threshold configuration of 1E-5. In contrast, the 95% high confidence setting also failed to predict the trajectory containing the acceptable error not beyond 1E-3. Thus, a proposed trade-off strategy between two contradictory expections (>50% confidence, <1E-3 error) supports 61% of investigated countries to predict the varying trajectory with confidence beyond 50%. Moreover, PMC model recommend the remanent 39% countries to extend the proportion of populaces in COVID-19 detecting-pool to a suggested-value (>1% of populations), ensuing the average confidence up to 70%.
Preprint
Full-text available
During the COVID-19 pandemic international health organizations and most national health ministries have treated a single positive result from a PCR-based test as confirmation of SARS-CoV-2 infection, even in asymptomatic persons without any history of exposure. This is based on a widespread belief that positive results in these tests are always reliable. However, data from external quality assessments of PCR-based tests for similar viruses show that PCR-based testing produces enough false positive results to make positive results highly unreliable over a broad range of real-world scenarios. This has clinical and case management implications, and affects several epidemiological statistics, including the asymptomatic ratio, prevalence, and hospitalization and death rates. Measures to raise awareness of false positives, reduce their frequency, and mitigate their effects should be considered. In the interim, positive results in asymptomatic individuals that haven't been confirmed by a second test should be considered suspect.
Article
Worldwide there are currently over 1200 research studies being performed on the topic of COVID-19. Many of these involve children and adults over age 65 years. There are also numerous studies testing investigational vaccines on healthy volunteers. No research team is exempt from the pressures and speed at which COVID-19 research is occurring. And this can increase the risk of honest error as well as misconduct. To date, 33 papers have been identified as unsuitable for public use and either retracted, withdrawn, or noted with concern. Asia is the source of most of these manuscripts (n=19; 57.6%) with China the largest Asian subgroup (n=11; 57.9%). This paper explores these findings and offers guidance for responsible research practice during pandemics.
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RESUMEN El tratamiento de SARS-Cov-2 con criterio naturista nos recuerda la gran capacidad curativa de nuestro propio cuerpo y el uso de los remedios más sencillos siguen siendo lo más eficaz para restablecer la salud y controlar la epidemia. ABSTRACT The treatment of SARS-Cov-2 with naturopathic criteria reminds us of the great healing capacity of our own body and the use of the simplest remedies that are still the most effective to restore health. and control the epidemic.
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The COVID-19 pandemic started in 2019, and multiple public health preventive measures have been taken, such as PCR tests preoperatively and for pre-and post-travel requirements. However, preventive health services have faced different dilemmas, particularly the issue of false-positive PCR test results, which were confirmed as the repeated tests were negative. People face different consequences after a positive PCR test result, such as postponing surgery, absence from work, and financial problems, all of which negatively impact people’s lives. Health care practitioners working in preventive medicine and public health departments bear the brunt of the anger from patients when they encounter such cases. Therefore, there is a need for a fixed guideline regarding the false positive swabs and how to clear the person from isolation when all criteria suggest the person is no longer contagious.
Article
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Retraction Watch maintains a "running list" of retracted papers on Covid-19 related research. By the end of September 2020, thirty-three retracted Covid-19 papers were listed. We analysed these retracted papers, focusing specifically on how they have been cited by review papers, and subsequently how they have penetrated and potentially distorted public discourse and legitimate research on Covid-19. The study demonstrates the need for more in-depth studies that focus on the phenomenon of citation pollution. We show that the "Covid-19 publication race", amplified by a pressure-to-publish research culture, distorted published science on Covid-19. We highlight the urgency to engage popular media and critical decision-makers on how to distinguish between questionable and legitimate science. We also emphasise the importance of dealing with illegitimate research timely, both from scholarly communications and research quality perspectives.
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