Testing Denmark: A Danish nationwide surveillance study of COVID-19

Background National data on the spread of SARS-CoV-2 infection and knowledge on associated risk factors are important for understanding the course of the pandemic. Testing Denmark is a national large-scale epidemiological surveillance study of SARS-CoV-2 in the Danish population. Methods Between September and October 2020, approximately 1.3 million of 5.8 million Danish citizens (age > 15 years) were randomly invited to fill in an electronic questionnaire covering COVID-19 exposures and symptoms. The prevalence of SARS-CoV-2 antibodies was determined by Point-of Care rapid Test (POCT) distributed to participants home addresses. Findings In total 318,552 participants (24.5% invitees) completed the questionnaire and provided the result of the POCT. Of these, 2,519 (0.79%) were seropositive (median age 55 years) and women were more often seropositive than men, interquartile range (IQR) 42-64, 40.2% males. Of participants with a prior positive Polymerase Chain Reaction (PCR) test (n=1,828), 29.1% were seropositive in the POCT. Seropositivity increased with age irrespective of sex. Elderly participants (>61 years) reported less symptoms and had less frequently been tested for SARS-CoV-2 compared to younger participants. Seropositivity was associated with physical contact with SARS-CoV-2 infected individuals (Risk ratio (RR) 7.43, 95% CI: 6.57-8.41) and in particular household members (RR 17.70, 95% CI: 15.60-20.10). Home care workers had a higher risk of seropositivity (RR 2.09 (95% CI: 1.58-2.78) as compared to office workers. Geographic population density was not associated to seropositivity. A high degree of compliance with national preventive recommendations was reported (e.g., > 80% use of face masks), but no difference was found between seropositive and seronegative participants. Interpretation This study provides insight into the immunity of the Danish population seven to eight months after the first COVID-19 case in Denmark. The seroprevalence was lower than expected probably due to a low sensitivity of the POCT used or due to challenges relating to the reading of test results. Occupation or exposure in local communities were major routes of infection. As elderly participants were more often seropositive despite fewer symptoms and less PCR tests performed, more emphasis should be placed on testing this age group.

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CRISPR-Cas Systems for Diagnosing Infectious Diseases

10.20944/preprints202002.0007.v1 ◽

2020 ◽

Cited By ~ 1

Author(s):

Anastasiya Kostyusheva ◽

Sergey Brezgin ◽

Yurii Babin ◽

Irina Vasil'eva ◽

Dmitry Kostyushev ◽

...

Keyword(s):

Infectious Diseases ◽

Molecular Diagnostics ◽

Large Scale ◽

Point Of Care ◽

Disease Spread ◽

Detection Methods ◽

Epidemiological Surveillance ◽

Molecular Diagnostic ◽

Diagnostic Tools ◽

Wide Range

Infectious diseases are a global health problem affecting billions of people. Developing rapid and sensitive diagnostic tools is key for successful patient management and curbing disease spread. Currently available diagnostics are very specific and sensitive but time-consuming and require expensive laboratory settings and well-trained personnel; thus, they are not available in resource-limited areas, for the purposes of large-scale screenings and in case of outbreaks and epidemics. Developing new, rapid, and affordable point-of-care diagnostic assays is urgently needed. This review focuses on CRISPR-based technologies and their perspectives to become platforms for point-of-care nucleic acid detection methods and as deployable diagnostic platforms that could help to identify and curb outbreaks and emerging epidemics. We describe the mechanisms and function of different classes and types of CRISPR-Cas systems, including pros and cons for developing molecular diagnostic tests and applications of each type to detect a wide range of infectious agents. Many Cas proteins (Cas9, Cas12, Cas13, Cas14) have been leveraged to create highly accurate and sensitive diagnostic tools combined with technologies of signal amplification and fluorescent, potentiometric, colorimetric, or lateral flow assay detection. In particular, the most advanced platforms -- SHERLOCK/v2, DETECTR, or CRISPR-Chip -- enable detection of attomolar amounts of pathogenic nucleic acids with specificity comparable to that of PCR but with minimal technical settings. Further developing CRISPR-based diagnostic tools promises to dramatically transform molecular diagnostics, making them easily affordable and accessible virtually anywhere in the world. The burden of socially significant diseases, frequent outbreaks, recent epidemics (MERS, SARS and the ongoing coronoviral nCov-2019 infection) urgently need the developing of express-diagnostic tools. Recently devised CRISPR-technologies represent the unprecedented opportunity to reshape epidemiological surveillance and molecular diagnostics.

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Accessible LAMP-Enabled Rapid Test (ALERT) for Detecting SARS-CoV-2

Viruses ◽

10.3390/v13050742 ◽

2021 ◽

Vol 13 (5) ◽

pp. 742

Author(s):

Ali Bektaş ◽

Michael F. Covington ◽

Guy Aidelberg ◽

Anibal Arce ◽

Tamara Matute ◽

...

Keyword(s):

Large Scale ◽

Point Of Care ◽

False Negative ◽

Rapid Test ◽

High Sensitivity ◽

Surface Proteins ◽

Influenza B ◽

True Negative ◽

Free Concentration ◽

Primer Sets

The coronavirus disease 2019 (COVID-19) pandemic has highlighted bottlenecks in large-scale, frequent testing of populations for infections. Polymerase chain reaction (PCR)-based diagnostic tests are expensive, reliant on centralized labs, can take days to deliver results, and are prone to backlogs and supply shortages. Antigen tests that bind and detect the surface proteins of a virus are rapid and scalable but suffer from high false negative rates. To address this problem, an inexpensive, simple, and robust 60-minute do-it-yourself (DIY) workflow to detect viral RNA from nasal swabs or saliva with high sensitivity (0.1 to 2 viral particles/μL) and specificity (>97% true negative rate) utilizing reverse transcription loop-mediated isothermal amplification (RT-LAMP) was developed. ALERT (Accessible LAMP-Enabled Rapid Test) incorporates the following features: (1) increased shelf-life and ambient temperature storage, compared to liquid reaction mixes, by using wax layers to isolate enzymes from other reagents; (2) improved specificity compared to other LAMP end-point reporting methods, by using sequence-specific QUASR (quenching of unincorporated amplification signal reporters); (3) increased sensitivity, compared to methods without purification through use of a magnetic wand to enable pipette-free concentration of sample RNA and cell debris removal; (4) quality control with a nasopharyngeal-specific mRNA target; and (5) co-detection of other respiratory viruses, such as influenza B, by multiplexing QUASR-modified RT-LAMP primer sets. The flexible nature of the ALERT workflow allows easy, at-home and point-of-care testing for individuals and higher-throughput processing for labs and hospitals. With minimal effort, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific primer sets can be swapped out for other targets to repurpose ALERT to detect other viruses, microorganisms, or nucleic acid-based markers.

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The sensitivity of SARS-CoV-2 antigen tests in the view of large-scale testing

10.1101/2020.11.23.20237198 ◽

2020 ◽

Cited By ~ 1

Author(s):

Pavel Drevinek ◽

Jakub Hurych ◽

Zdenek Kepka ◽

Ales Briksi ◽

Michal Kulich ◽

...

Keyword(s):

Large Scale ◽

Point Of Care ◽

Rapid Test ◽

Antigen Test ◽

Repeated Testing ◽

Diagnostic Pcr ◽

Large Scale Testing ◽

Oropharyngeal Swab ◽

Antigen Tests ◽

Low Sensitivity

AbstractObjectivesAntigen tests have recently emerged as an interesting alternative to SARS-CoV-2 diagnostic PCR, thought to be valuable especially for the screening of bigger communities. To check appropriateness of the antigen based testing, we determined sensitivity of two point-of-care antigen tests when applied to a cohort of COVID-19 symptomatic, COVID-19 asymptomatic and healthy persons.MethodsWe examined nasopharyngeal swabs with antigen test 1 (Panbio Covid-19 Ag Rapid Test, Abbott) and antigen test 2 (Standard F Covid-19 Ag FIA, SD Biosensor). An additional nasopharyngeal and oropharyngeal swab of the same individual was checked with PCR (Allplex SARS-nCoV-2, Seegene). Within a 4-day period in October 2020, we collected specimens from 591 subjects. Of them, 290 had COVID-19 associated symptoms.ResultsWhile PCR positivity was detected in 223 cases, antigen test 1 and antigen test 2 were found positive in 148 (sensitivity 0.664, 95% CI 0.599 - 0.722) and 141 (sensitivity 0.623, 95% CI 0.558 - 0.684) patients, respectively. When only symptomatic patients were analysed, sensitivity increased to 0.738 (95% CI 0.667 - 0.799) for the antigen test 1 and to 0.685 (95% CI 0.611 - 0.750) for the antigen test 2. The substantial drop in sensitivity to 12.9% (95% CI 0.067 - 0.234) was observed for samples with the PCR threshold cycle above > 30.ConclusionsLow sensitivity of antigen tests leads to the considerable risk of false negativity. It is advisable to implement repeated testing with high enough frequency if the antigen test is used as a frontline screening tool.

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Accessible LAMP-Enabled Rapid Test (ALERT) for detecting SARS-CoV-2

10.1101/2021.02.18.21251793 ◽

2021 ◽

Author(s):

Ali Bektaş ◽

Michael F. Covington ◽

Guy Aidelberg ◽

Anibal Arce ◽

Tamara Matute ◽

...

Keyword(s):

Large Scale ◽

Point Of Care ◽

False Negative ◽

Rapid Test ◽

High Sensitivity ◽

Surface Proteins ◽

Influenza B ◽

True Negative ◽

Free Concentration ◽

Primer Sets

AbstractThe COVID-19 pandemic has highlighted bottlenecks in large-scale, frequent testing of populations for infections. PCR-based diagnostic tests are expensive, reliant on expensive centralized labs, can take days to deliver results, and are prone to backlogs and supply shortages. Antigen tests, that bind and detect the surface proteins of a virus, are rapid and inexpensive but suffer from high false negative rates. To address this problem, we have created an inexpensive, simple, and robust 60-minute Do-It-Yourself (DIY) workflow to detect viral RNA from nasal swabs or saliva with high sensitivity (0.1 to 2 viral particles/µl) and specificity (>97% True Negative Rate) utilizing reverse transcription loop-mediated isothermal amplification (RT-LAMP).Our workflow, ALERT (Accessible LAMP-Enabled Rapid Test), incorporates the following features: 1) Increased shelf-life and ambient temperature storage by using wax layers to isolate enzymes from reaction, 2) Improved specificity by using sequence-specific QUASR reporters, 3) Increased sensitivity through use of a magnetic wand to enable pipette-free concentration of sample RNA and cell debris removal, 4) Quality control with a nasopharyngeal-specific mRNA target, and 5) Co-detection of other respiratory viruses, such as Influenza B, by duplexing QUASR-modified RT-LAMP primer sets.The flexible nature of the ALERT workflow allows easy, at-home and point-of-care testing for individuals and higher-throughput processing for centralized labs and hospitals. With minimal effort, SARS-CoV-2-specific primer sets can be swapped out for other targets to repurpose ALERT to detect other viruses, microorganisms or nucleic acid-based markers.

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A flu optical immunoassay (ThermoBioStar'sFLU OIA): a diagnostic tool for improved influenza management

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2001.1005 ◽

2001 ◽

Vol 356 (1416) ◽

pp. 1915-1924 ◽

Cited By ~ 4

Author(s):

S. P. Tucker ◽

C. Cox ◽

J. Steaffens

Keyword(s):

Influenza A ◽

Large Scale ◽

Point Of Care ◽

Rapid Test ◽

Epidemiological Data ◽

Influenza Viruses ◽

Detection Methods ◽

Laboratory Characterization ◽

The Face ◽

Influenza Outbreaks

ThermoBioStar'sand Biota'sflu optical immunoassay (FLU OIA) is a rapid test designed to diagnose influenza A and B infection using a variety of specimen types. The assay uses highly sensitive thin–film detection methods, coupled with specific monoclonal antibodies to the nucleoprotein. The test is simple to perform, requires no instrumentation and is intended to provide a result within 15min of test initiation in the ‘point–of–care’ environment. In initial clinical studies, the assay was demonstrated to be equivalent to culture in identifying infected individuals. Subsequent independent studies using a variety of sample types have demonstrated sensitivity ranging from 48 to 100% and specificities ranging from 93 to 97%. In addition to detecting human strains, this assay has been demonstrated to be capable of detecting a variety of avian and non–human mammalian influenza viruses. The FLU OIA test has been used in large–scale surveillance schemes intended to provide rapid epidemiological data during normal influenza seasons and has demonstrated the potential for fulfilling a similar role for multispecies surveillance in, for example, conditions that offer challenges for conventional virus isolation methods. Conceivably, such use should facilitate the timely recognition of influenza outbreaks and prioritization of positive specimens for more conventional, laboratory characterization, leading to improved interpandemic surveillance and rapid reaction in the face of the next pandemic.

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Early detection of COVID-19 in the UK using self-reported symptoms: a large-scale, prospective, epidemiological surveillance study

The Lancet Digital Health ◽

10.1016/s2589-7500(21)00131-x ◽

2021 ◽

Author(s):

Liane S Canas ◽

Carole H Sudre ◽

Joan Capdevila Pujol ◽

Lorenzo Polidori ◽

Benjamin Murray ◽

...

Keyword(s):

Early Detection ◽

Large Scale ◽

Surveillance Study ◽

Epidemiological Surveillance ◽

The Uk

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Testing for resistance: Point-of-care testing as a communicational tool in antibiotic prescribing

Communication & Medicine ◽

10.1558/cam.32191 ◽

2018 ◽

Vol 14 (3) ◽

pp. 229-240

Author(s):

Johanna Lindell

Keyword(s):

Point Of Care ◽

Rapid Test ◽

Antibiotic Use ◽

Treatment Recommendation ◽

Antibiotic Prescribing ◽

Communicative Practices ◽

Effective Strategies ◽

Reactive Protein ◽

Point Of Care Test ◽

Test Result

As antibiotic resistance becomes a growing health emergency, effective strategies are needed to reduce inappropriate antibiotic use. In this article, one such strategy – communicative practices associated with the C-reactive protein point-of care test – is investigated. Building on a collection of 31 videorecorded consultations from Danish primary care, and using conversation analysis, this study finds that the rapid test can be used throughout the consultation to incrementally build the case for a nonantibiotic treatment recommendation, both when the test result is forecast and reported. The study also finds that the format of reports of elevated results differs from that of ‘normal’ results, resulting in a subtle shift of authority from doctor to test.

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Integrating syphilis screening in a large-scale HIV prevention program for key populations: the Avahan experience from India

The Journal of Infection in Developing Countries ◽

10.3855/jidc.2810 ◽

2013 ◽

Vol 7 (06) ◽

pp. 484-488 ◽

Cited By ~ 4

Author(s):

Mugundu Ramien Parthasarathy ◽

Prakash Narayanan ◽

Anjana Das ◽

Anup Gurung ◽

Parimi Prabhakar ◽

...

Keyword(s):

Hiv Prevention ◽

Prevention Program ◽

Large Scale ◽

Point Of Care ◽

Key Populations ◽

Immunochromatographic Strip ◽

Transmitted Infection ◽

Sexually Transmitted ◽

Syphilis Screening ◽

Strip Test

Introduction: Documented experiences from India on the implementation of syphilis screening in large-scale HIV prevention programs for “key populations at higher risk’ (KPs) are limited. Avahan is a large-scale HIV prevention program providing services to more than 300,000 KPs in six high HIV prevalence states of India since 2004. Avahan clinics provide a sexually transmitted infection service package which includes bi-annual syphilis screening. The trends in the coverage of syphilis screening among Avahan clinic attendees were studied retrospectively. Methodology: Screening was performed using either the Rapid Plasma Reagin (RPR) test or point-of-care immunochromatographic strip test (ICST). Clinic records from 2005 to 2009 were collated in an individual tracking database and analyzed with STATA-10. Results: Initially the coverage of syphilis screening (2.6% in 2005) was constrained by the availability and operational complexity of the RPR test. After its introduction in 2007, the use of ICST for screening increased from 7.4% to 77.0% and the proportion of clinic attendees screened increased from 9.0% to 21.6% during 2007-2009. The RPR reactivity rates declined from 6.6% (2006) to 4.4% (2009). Conclusion: The data showed improved rates of screening of clinic attendees and declining trends in sero-reactivity over time. The introduction of point-of-care syphilis tests may have contributed to the improved coverage of syphilis screening. The ICST may be considered for initial syphilis screening at other resource-constrained primary care sites in India such as ante-natal clinics and other KP interventions.

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Diagnosis of Herpes Simplex Virus: Laboratory and Point-of-Care Techniques

Infectious Disease Reports ◽

10.3390/idr13020049 ◽

2021 ◽

Vol 13 (2) ◽

pp. 518-539

Author(s):

Peuli Nath ◽

Md Alamgir Kabir ◽

Somaiyeh Khoubafarin Doust ◽

Aniruddha Ray

Keyword(s):

Herpes Simplex Virus ◽

Herpes Simplex ◽

Point Of Care ◽

Diagnostic Techniques ◽

Nucleic Acid Amplification ◽

Physical Contact ◽

Detection Sensitivity ◽

Detection Techniques ◽

Advantages And Disadvantages ◽

Simplex Virus

Herpes is a widespread viral infection caused by the herpes simplex virus (HSV) that has no permanent cure to date. There are two subtypes, HSV-1 and HSV-2, that are known to cause a variety of symptoms, ranging from acute to chronic. HSV is highly contagious and can be transmitted via any type of physical contact. Additionally, viral shedding can also happen from asymptomatic infections. Thus, early and accurate detection of HSV is needed to prevent the transmission of this infection. Herpes can be diagnosed in two ways, by either detecting the presence of the virus in lesions or the antibodies in the blood. Different detection techniques are available based on both laboratory and point of care (POC) devices. Laboratory techniques include different biochemical assays, microscopy, and nucleic acid amplification. In contrast, POC techniques include microfluidics-based tests that enable on-spot testing. Here, we aim to review the different diagnostic techniques, both laboratory-based and POC, their limits of detection, sensitivity, and specificity, as well as their advantages and disadvantages.

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