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1.
Clin Biochem ; 2022 Apr 16.
Article in English | MEDLINE | ID: covidwho-2294856

ABSTRACT

Testing for SARS-CoV-2 is crucial to tracking and controlling the pandemic. In particular, rapid testing in settings such as the emergency department (ED) could improve time to diagnosis and promote proper infection control measures. Early in the COVID-19 pandemic, we implemented the Abbott ID NOW COVID-19 method for screening symptomatic ED patients. However, due to concerns of suboptimal sensitivity, samples with a negative result were reflexed to the lab for confirmatory testing by the TaqPath COVID-19 Combo RT-PCR method. This study analyzed 6773 ID NOW results from April 2020 to September 2020 in the ED, of which 10% (n = 673) were positive and reported directly. The rest 90% (n = 6100) were negative and reflexed to RT-PCR. Among them, 3% (n = 175) turned positive on RT-PCR while 97% (n = 5925) of the results were consistently negative. The cycle threshold (Ct) values of the false-negative samples (n = 175) showed 90% (n = 158) of them with relatively low viral loads (Ct ≥ 30) with median Ct value at 35, while a number of samples (n = 17) had low Ct values (Ct < 30) and no clear explanation for false-negative results. Our study demonstrates that the Abbott ID NOW, despite it's sensitivity limitations, was capable of providing near real-time results for 10% of symptomatic patients presenting to the ED allowing for improved management and workflow. However, our study findings emphasize the need to reflex negative specimens to a higher sensitivity method when prevalence is high and false-negative results are intolerable.

2.
J Clin Virol Plus ; 2(1): 100065, 2022 Feb.
Article in English | MEDLINE | ID: covidwho-2292717

ABSTRACT

In the context of SARS-CoV-2 pandemic, rapid and easy-to-perform diagnostic methods are essential to limit the spread of the virus and for the clinical management of COVID-19 patients. Although real-time polymerase chain reaction remains the "gold standard" to diagnose acute infections, this technique is expensive, requires trained personnel, well-equipped laboratory and is time-consuming. A prospective evaluation of the Abbott ID NOW COVID-19 point-of-care testing that uses isothermal nucleic acid amplification for the qualitative detection of SARS-CoV-2 RdRp gene was run in the Emergency Department during the third wave of COVID-19 pandemic. ID-NOW significantly simplified SARS-CoV-2 identification and COVID-19 patient triaging, being highly valuable in rapidly locating febrile patients in or out of COVID-19 areas, and can be considered as a first-line diagnostic test in the Emergency Room setting.

3.
Journal of Laboratory and Precision Medicine ; 7, 2022.
Article in English | Scopus | ID: covidwho-2262685

ABSTRACT

The evolution of the coronavirus disease 2019 (COVID-19) pandemic and widespread community of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variants continues to present new challenges for early phase clinical trials and COVID-19 diagnostic strategies. Many regulatory agencies, including the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) continue to provide updated guidance on the operations of clinical trials during the pandemic. However, guidance is limited with respect to medical and scientific specific issues, such as COVID-19 diagnostics. Here we discuss, the challenges for early phase studies associated with COVID-19 diagnostics in the Omicron era and potential risk mitigation strategies in the face of continued widespread community transmission. We note how careful consideration and planning can help mitigating the risk of COVID-19 impacting the medical and scientific validity and patient safety in clinical trials. Clinical study design should consider mitigation strategies at the patient, investigator, and clinical research organization (CRO)/Sponsor level following evaluation of the overall for their specific study/investigational product and patient overall wellbeing. Specific language regarding COVID-19-related policies and procedures should be included in the study protocol. Special considerations should be taken for novel immunotherapeutics which may require interruption in the event of a subject developing COVID-19 or for investigative products that may have hazardous interactions with commonly prescribed anti-COVID-19 therapies. Moving forward, its essential for trials to remain adaptable to evolving nature of the pandemic. © Journal of Laboratory and Precision Medicine. All rights reserved.

5.
Clin Lab Med ; 42(2): 283-298, 2022 06.
Article in English | MEDLINE | ID: covidwho-2130436

ABSTRACT

Deployment of molecular testing for SARS-CoV-2 in resource-limited settings is challenging. Scale-up of molecular had to be conducted with a laboratory system strengthening approach that emphasize laboratory integration. National reference laboratories play a central role. In Malawi the molecular testing was underpinned by existing pathogen control programs for human immunodeficiency virus and tuberculosis that use Abbott and GeneXpert machines and reagents. Despite this, the impact on these programs was well managed. Antigen testing increased access to testing. Pooled testing and direct-to-polymerase chain reaction methods have the potential to save costs and further increase access to molecular tests.


Subject(s)
COVID-19 , HIV Infections , COVID-19/diagnosis , Humans , Molecular Diagnostic Techniques , Polymerase Chain Reaction , SARS-CoV-2/genetics
6.
Clin Lab Med ; 42(2): 261-282, 2022 06.
Article in English | MEDLINE | ID: covidwho-2130434

ABSTRACT

Scaling up SARS-CoV-2 testing during the COVID-19 pandemic was critical to maintaining clinical operations and an open society. Pooled testing and automation were two critical strategies used by laboratories to meet the unprecedented demand. Here, we review these and other cutting-edge strategies that sought to expand SARS-CoV-2 testing capacity while maintaining high individual test performance.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/diagnosis , COVID-19 Testing , Humans , Molecular Diagnostic Techniques , Pandemics
7.
BMC Infect Dis ; 22(1): 763, 2022 Sep 30.
Article in English | MEDLINE | ID: covidwho-2053867

ABSTRACT

BACKGROUND: The COVID-19 pandemic was met with strict containment measures. We hypothesized that societal infection control measures would impact the number of hospital admissions for respiratory tract infections, as well as, the spectrum of pathogens detected in patients with suspected community acquired pneumonia (CAP). METHODS: This study is based on aggregated surveillance data from electronic health records of patients admitted to the hospitals in Bergen Hospital Trust from January 2017 through June 2021, as well as, two prospective studies of patients with suspected CAP conducted prior to and during the COVID-19 pandemic (pre-COVID cohort versus COVID cohort, respectively). In the prospective cohorts, microbiological detections were ascertained by comprehensive PCR-testing in lower respiratory tract specimens. Mann-Whitney's U test was used to analyse continuous variables. Fisher's exact test was used for analysing categorical data. The number of admissions before and during the outbreak of SARS-CoV-2 was compared using two-sample t-tests on logarithmic transformed values. RESULTS: Admissions for respiratory tract infections declined after the outbreak of SARS-CoV-2 (p < 0.001). The pre-COVID and the COVID cohorts comprised 96 and 80 patients, respectively. The proportion of viruses detected in the COVID cohort was significantly lower compared with the pre-COVID cohort [21% vs 36%, difference of 14%, 95% CI 4% to 26%; p = 0.012], and the proportion of bacterial- and viral co-detections was less than half in the COVID cohort compared with the pre-COVID cohort (19% vs 45%, difference of 26%, 95% CI 13% to 41%; p < 0.001). The proportion of bacteria detected was similar (p = 0.162), however, a difference in the bacterial spectrum was observed in the two cohorts. Haemophilus influenzae was the most frequent bacterial detection in both cohorts, followed by Streptococcus pneumoniae in the pre-COVID and Staphylococcus aureus in the COVID cohort. CONCLUSION: During the first year of the COVID-19 pandemic, the number of admissions with pneumonia and the microbiological detections in patients with suspected CAP, differed from the preceding year. This suggests that infection control measures related to COVID-19 restrictions have an overall and specific impact on respiratory tract infections, beyond reducing the spread of SARS-CoV-2.


Subject(s)
COVID-19 , Community-Acquired Infections , Pneumonia , Respiratory Tract Infections , COVID-19/epidemiology , Community-Acquired Infections/epidemiology , Humans , Pandemics , Pneumonia/epidemiology , Prospective Studies , Respiratory Tract Infections/epidemiology , SARS-CoV-2
8.
Adv Med Sci ; 67(2): 386-392, 2022 Sep.
Article in English | MEDLINE | ID: covidwho-2031074

ABSTRACT

PURPOSE: From April to September 2020, Poland was minimally affected by COVID-19 compared to other EU countries. We aimed to investigate the risks of false reverse transcription polymerase chain reaction (RT-PCR) results during the first wave (compared to later waves), that rises when cycle threshold (Ct) of positive result is close to limit of detection (LOD). MATERIALS/METHODS: We analyzed Ct values of SARS-CoV-2 positive RT-PCR results of 7726 patients in Poland from April-September 2020. SARS-CoV-2 positive RT-PCR results of 14,534 patients in the 2nd-3rd wave and 10,861 patients in the 4th-5th pandemic waves were used. Statistical analysis was based on one-way analysis of variance. To verify, 95% confidence intervals with Bonferroni correction were computed. Incidence of SARS-CoV-2 variants in Poland was analyzed using Whole Genome Sequencing from 923 (3.6%) patients. RESULTS: The mean Ct of RT-PCR positive test results analyzed ranged between 22.89 and 26.71 depending on the month of the results collection. The differences between months were significant (p â€‹< â€‹0.001). Differences in Ct were observed between age groups, with younger patients displaying higher Ct values, however, major trends over time were paralleled between age groups. CONCLUSIONS: The mean Ct of the tested RT-PCR positive test results was lower than 35 which is considered an upper borderline for reliable positive results of the assay. Therefore, most COVID-19 cases recorded in Poland from April to September 2020 were detected with minor risks of inaccuracy. Data from a single center exhibited greater consistency for both virus Ct level and SARS-CoV-2 virus variant identification.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , SARS-CoV-2/genetics , Pandemics , COVID-19/diagnosis , COVID-19/epidemiology , Reverse Transcriptase Polymerase Chain Reaction , Poland/epidemiology , Sensitivity and Specificity
9.
Int J Immunopathol Pharmacol ; 36: 3946320221115316, 2022.
Article in English | MEDLINE | ID: covidwho-1938171

ABSTRACT

COVID-19, a novel coronavirus disease, has provoked a variety of health and safety concerns, and socioeconomic challenges around the globe. The laboratory diagnosis of SARS-CoV-2 was quickly established utilizing nucleic acid amplification techniques (NAAT) after the disease causing virus has been identified, and its genetic sequence has been determined. In addition to NAAT, serological tests based on antibodies testing against SARS-CoV-2 were introduced for diagnostic and epidemiologic studies. Other biochemical investigations include monitoring of peripheral blood cells count, platelets/lymphocyte ratio, coagulation profile, cardiac, and inflammatory markers such as cytokines storm are also crucial in combating COVID-19 pandemic. Further, accurate and reliable laboratory results for SARS-CoV-2 play very important role in the initiation of early treatment and timely management of COVID-19 patients, provide support in clinical decision-making process to control infection, and detection of asymptomatic cases. The Task Force on Coronavirus-19 constituted by International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) has recognized informational framework for epidemiology, pathogenesis, and recommended the PCR-based analysis, serological and biochemical assays for analysis, monitoring, and management of disease. This literature review provides an overview of the currently used diagnostic techniques in clinical laboratories for the diagnosis, treatment monitoring, and management of COVID-19 patients. We concluded that each assays differ in their performance characteristics and the utilization of multiple techniques is necessary for the accurate diagnosis and management of SARS-CoV-2 infection.


Subject(s)
COVID-19 , SARS-CoV-2 , Biomarkers , COVID-19/diagnosis , Clinical Laboratory Techniques/methods , Humans , Laboratories, Clinical , Pandemics
10.
Revista de Biologia Tropical ; 70(1):173-189, 2022.
Article in English | Scopus | ID: covidwho-1863423

ABSTRACT

Introduction: Most successful cases of COVID-19 pandemic mitigation and handling have relied on extensive reverse-transcription quantitative polymerase chain reaction (RT-qPCR). However, many emerging economies have struggled with current molecular testing demands due to economic, technical and technological constraints. Objective: To define a potential diagnostic protocol to increase testing capacity in current and post-pandemic conditions. Methods: We reviewed the literature, patents and commercial applications, for alternatives. Results: We found a good potential in saliva samples, viral inactivation and quick RNA extraction by heating;the use of an isothermal technology such as loop mediated isothermal amplification (LAMP) and naked eye test-result visualization by in-tube colorimetry or turbidity. Conclusions: Saliva samples with quick RNA extraction by heating and colorimetric LAMP are promising options for countries with economic and infrastructure limitations. © 2022, Universidad de Costa Rica. All rights reserved.

11.
Crit Rev Clin Lab Sci ; 59(7): 445-459, 2022 Nov.
Article in English | MEDLINE | ID: covidwho-1740611

ABSTRACT

A plethora of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) diagnostic tests are available, each with different performance specifications, detection methods, and targets. This narrative review aims to summarize the diagnostic technologies available and how they are best selected to tackle SARS-CoV-2 infection as the pandemic evolves. Seven key settings have been identified where diagnostic tests are being deployed: symptomatic individuals presenting for diagnostic testing and/or treatment of COVID-19 symptoms; asymptomatic individuals accessing healthcare for planned non-COVID-19-related reasons; patients needing to access emergency care (symptom status unknown); patients being discharged from healthcare following hospitalization for COVID-19; healthy individuals in both single event settings (e.g. airports, restaurants, hotels, concerts, and sporting events) and repeat access settings (e.g. workplaces, schools, and universities); and vaccinated individuals. While molecular diagnostics remain central to SARS-CoV-2 testing strategies, we have offered some discussion on the considerations for when other tools and technologies may be useful, when centralized/point-of-care testing is appropriate, and how the various additional diagnostics can be deployed in differently resourced settings. As the pandemic evolves, molecular testing remains important for definitive diagnosis, but increasingly widespread point-of-care testing is essential to the re-opening of society.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , COVID-19 Testing , COVID-19/diagnosis , Pandemics , Point-of-Care Testing , Sensitivity and Specificity
12.
Viruses ; 12(6)2020 05 26.
Article in English | MEDLINE | ID: covidwho-1726015

ABSTRACT

The recent outbreak of the Coronavirus disease 2019 (COVID-19) has quickly spread worldwide since its discovery in Wuhan city, China in December 2019. A comprehensive strategy, including surveillance, diagnostics, research, clinical treatment, and development of vaccines, is urgently needed to win the battle against COVID-19. The past three unprecedented outbreaks of emerging human coronavirus infections at the beginning of the 21st century have highlighted the importance of readily available, accurate, and rapid diagnostic technologies to contain emerging and re-emerging pandemics. Real-time reverse transcriptase-polymerase chain reaction (rRT-PCR) based assays performed on respiratory specimens remain the gold standard for COVID-19 diagnostics. However, point-of-care technologies and serologic immunoassays are rapidly emerging with high sensitivity and specificity as well. Even though excellent techniques are available for the diagnosis of symptomatic patients with COVID-19 in well-equipped laboratories; critical gaps still remain in screening asymptomatic people who are in the incubation phase of the virus, as well as in the accurate determination of live viral shedding during convalescence to inform decisions for ending isolation. This review article aims to discuss the currently available laboratory methods and surveillance technologies available for the detection of COVID-19, their performance characteristics and highlight the gaps in current diagnostic capacity, and finally, propose potential solutions. We also summarize the specifications of the majority of the available commercial kits (PCR, EIA, and POC) for laboratory diagnosis of COVID-19.


Subject(s)
Clinical Laboratory Techniques , Coronavirus Infections/diagnosis , Pneumonia, Viral/diagnosis , Asymptomatic Infections , Betacoronavirus , COVID-19 , COVID-19 Testing , COVID-19 Vaccines , Humans , Immunoenzyme Techniques , Neutralization Tests , Nucleic Acid Amplification Techniques , Pandemics , Point-of-Care Testing , Reagent Kits, Diagnostic/standards , Real-Time Polymerase Chain Reaction , Reverse Transcriptase Polymerase Chain Reaction , SARS-CoV-2 , Sensitivity and Specificity , Serologic Tests , Tomography, X-Ray Computed , Virus Shedding
13.
Journal of Clinical and Diagnostic Research ; 15(9):DC11-DC15, 2021.
Article in English | Web of Science | ID: covidwho-1700969

ABSTRACT

Introduction: The emergence of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) pandemic has been troublesome particularly for developing countries that lack infrastructure and capacities to produce the kits locally. Simplification of the method can increase diagnostic efficiency which can benefit patients and help in infection control, consequently saving time and lives. Aim: To evaluate the diagnostic value of four methods (that omit extraction step) for detection of SARS-CoV-2 against the traditional extraction method. Materials and Methods: This was a cross-sectional analysis for evaluating diagnostic accuracy of four methods for detection of SARS-CoV-2 by real-time Reverse Transcriptase Polymerase Chain Reaction (rRT-PCR), conducted in the Department of Microbiology, SMS Medical College, Jaipur, Rajasthan, India, in October 2020. Ninety four SARS-CoV-2 RT-PCR positive samples and 20 negative samples were taken for this study. Automated extraction system was used for Ribonucleic Acid (RNA) extraction and four different approaches were compared to the traditional extraction method for detection of SARS-CoV-2 by RT-PCR. Data was entered and analysed using Statistical Package for the Social Sciences (SPSS) statistical software version 24.0. Results: The automated RNA extraction method was compared to the method of direct addition of samples with (Heat processed Direct Viral transport medium Sample (HDVS)) and without heating (Direct Viral transport medium Sample (DVS)), directs addition of diluted (1:5) sample with (Heat processed diluted VTM sample (HdVS)) and without heating (Diluted VTM sample (dVS)) as well as after addition of Proteinse K (PK) to the diluted samples that came either negative/invalid. Out of four methods, the HdVS method gave the best results, considering extraction with Perkin Elmer as standard, this method showed sensitivity of 96.74%, specificity of 100%. Conclusion: In current pandemic, molecular testing is critically challenged by the limited supplies of reagents of nucleic acid extraction alternative method like diluting and heating of Viral Transport Media (VTM) samples and using them directly as elutes serve as an easy, fast and inexpensive alternative.

14.
Diagnostics (Basel) ; 12(2)2022 Feb 12.
Article in English | MEDLINE | ID: covidwho-1686635

ABSTRACT

Rising SARS-CoV-2 cases, testing delays, and the risk of pre-symptomatic and asymptomatic transmission provided the impetus for an in-house rapid testing program. Employees and their household contacts were encouraged to self-collect saliva samples that were pooled for routine testing using an established colorimetric reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay. In brief, individual or a maximum of four saliva samples were pooled and heat-inactivated to render microorganisms, especially SARS-CoV-2, non-infectious prior to being added to RT-LAMP assay tubes containing either the human sample control gene, RNase P, or a region of the SARS-CoV-2 gene, ORF1ab. During the second wave of SARS-CoV-2 infections in November 2020, two samples from an employee and a member of their household tested positive via RT-LAMP within two days of each other. A delayed clinical qRT-PCR test confirmation of both individuals 5 days later underscored the power of routine rapid testing with within-the-hour turnaround times. Workplace rapid testing programs using RT-LAMP are flexible in their design, have a reduced cost compared to qRT-PCR, may involve non-invasive self-saliva collection for increased safety for the testing personnel, and can be performed with minimal training.

15.
Journal of Clinical Virology Plus ; : 100066, 2022.
Article in English | ScienceDirect | ID: covidwho-1632556

ABSTRACT

Background : Prior to the SARS-CoV-2 pandemic, the Xpert® Xpress Flu/RSV assay (GXA) was regularly used, while during the pandemic the Xpert® Xpress SARS-CoV-2/Flu/RSV plus assay was developed by Cepheid. In contrast to this new assay, the use of oropharyngeal ESwabs in combination with the Flu/RSV assay is designated as off CE-IVD label use, while these were used frequently in The Netherlands. Aim : To investigate the clinical performance of the GXA using 1,289 ESwab™ oropharyngeal samples for the detection of Influenza A virus, Influenza B virus and respiratory syncytial virus (RSV). Methods : The clinical performance of the GXA was prospectively investigated during the influenza seasons of 2017 and 2018 by testing fresh oropharyngeal samples, collected with ESwab™, contemporaneously with both the GXA and a laboratory developed Flu/RSV real time RT-PCR assay (LDA) (reference method). Results : 1,289 Samples from 1,213 patients (46% men, median age 73 (IQR 62-82)) were tested with both tests. Positive percent agreement (95% CI) was 98% (95%-99%) for Influenza A virus, 92% (88%-95%) for influenza B virus, and 88% (73%-96%) for RSV. Negative percent agreement was ≥ 99% for all three viruses. Ct-values of the GXA were on average higher than the LDA. Conclusion : This study showed a good clinical performance of the GXA in oropharyngeal samples for the detection of Influenza A and B virus. The positive percent agreement of the GXA for the detection of RSV in oropharyngeal samples was somewhat lower and in particular for the detection of RSV-A.

16.
Clin Chem Lab Med ; 60(5): 766-770, 2022 04 26.
Article in English | MEDLINE | ID: covidwho-1636222

ABSTRACT

OBJECTIVES: The reliable identification of individuals with SARS-CoV-2 infection is the cornerstone for containing viral spread. Rapid molecular point-of-care testing (POCT) of saliva might reduce analysis time, thus increasing the efficacy of contact tracing. In this study, a new POCT RT-PCR assay for the detection of SARS-CoV-2 RNA in saliva was evaluated and compared with an already validated CE-IVD method. METHODS: An evaluation was made of 160 left-over salivary samples (27 frozen, kept at -80 °C and 133 fresh), collected using Salivette (Sarstedt, Germany). Samples were analyzed by TaqPath COVID-19 CE-IVD RT-PCR kit, QuantStudio5 Real-Time (Applied Biosystems, USA) (TaqPath) and bKIT Virus Finder COVID-19 Saliva (Hyris Global Diagnostics, Italy). Performances of three- and fivefold pooling strategies were also evaluated. Blood assay interference in saliva was also tested with Hyris. RESULTS: On using TaqPath, SARS-CoV-2 positivity was detected in 35 samples. Another 10 positive samples were artificially-generated by blind mixing of positive with negative samples. Hyris positive and negative percentages of agreement were 97.6 (95% CI: 87.2-99.9%) and 100 (95% CI: 97.0-100%), respectively. Seventeen positive pools, evaluated for threefold strategy, were all correctly determined by both systems. For the 5-pool strategy, 94.7% (18/19) of samples resulted positive with the Hyris system, and 100% with TaqPath. The presence of 1% of blood (v/v) in saliva did not interfere with the accuracy of Hyris assay. CONCLUSIONS: The sensitivity and specificity of the bKIT Virus Finder COVID-19 Saliva were optimal with respect to TaqPath. In view of the safe and straightforward pre-analytical procedure involved, and the small size of the Hyris bCube, the Hyris system can be used for POCT.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/diagnosis , Humans , Point-of-Care Testing , RNA, Viral/analysis , RNA, Viral/genetics , SARS-CoV-2/genetics , Saliva/chemistry , Sensitivity and Specificity
17.
Diagnostics (Basel) ; 11(12)2021 Dec 07.
Article in English | MEDLINE | ID: covidwho-1554810

ABSTRACT

Starting in 2019, the COVID-19 pandemic is a global threat that is difficult to monitor. SARS-CoV-2 is known to undergo frequent mutations, including SNPs and deletions, which seem to be transmitted together, forming clusters that define specific lineages. Reverse-Transcription quantitative PCR (RT-qPCR) has been used for SARS-CoV-2 diagnosis and is still considered the gold standard method. Our Eukaryotic Host Pathogens Interaction (EHPI) laboratory received six SARS-CoV-2-positive samples from a Sicilian private analysis laboratory, four of which showed a dropout of the E gene. Our sequencing data revealed the presence of a synonymous mutation (c.26415 C > T, TAC > TAT) in the E gene of all four samples showing the dropout in RT-qPCR. Interestingly, these samples also harbored three other mutations (S137L-Orf1ab; N439K-S gene; A156S-N gene), which had a very low diffusion rate worldwide. This combination suggested that these mutations may be linked to each other and more common in a specific area than in the rest of the world. Thus, we decided to analyze the 103 sequences in our internal database in order to confirm or disprove our "mutation cluster hypothesis". Within our database, one sample showed the synonymous mutation (c.26415 C > T, TAC > TAT) in the E gene. This work underlines the importance of territorial epidemiological surveillance by means of NGS and the sequencing of samples with clinical and or technical particularities, e.g., post-vaccine infections or RT-qPCR amplification failures, to allow for the early identification of these SNPs. This approach may be an effective method to detect new mutational clusters and thus to predict new emerging SARS-CoV-2 lineages before they spread globally.

18.
Cell Rep Methods ; 1(7): 100093, 2021 Nov 22.
Article in English | MEDLINE | ID: covidwho-1474464

ABSTRACT

Low- and middle-income countries (LMICs) are significantly affected by SARS-CoV-2, partially due to their limited capacity for local production and implementation of molecular testing. Here, we provide detailed methods and validation of a molecular toolkit that can be readily produced and deployed using laboratory equipment available in LMICs. Our results show that lab-scale production of enzymes and nucleic acids can supply over 50,000 tests per production batch. The optimized one-step RT-PCR coupled to CRISPR-Cas12a-mediated detection showed a limit of detection of 102 ge/µL in a turnaround time of 2 h. The clinical validation indicated an overall sensitivity of 80%-88%, while for middle and high viral load samples (Cq ≤ 31) the sensitivity was 92%-100%. The specificity was 96%-100% regardless of viral load. Furthermore, we show that the toolkit can be used with the mobile laboratory Bento Lab, potentially enabling LMICs to implement detection services in unattended remote regions.

19.
J Virol Methods ; 299: 114340, 2022 01.
Article in English | MEDLINE | ID: covidwho-1474838

ABSTRACT

BACKGROUND: Screening of infectious asymptomatic or pre-symptomatic individuals for SARS-CoV-2 is at present a key to controling the COVID-19 pandemic. In order to expand testing capability and limit cost, pool testing of asymtomatic individuals has been proposed, provided assay performance is not significantly affected. METHODS: Combined nose and throat (N/T) swabs collected from COVID-19 infected or non-infected individuals were tested using SAMBA II individually and in pools of four (one positive and 3 negative). The evaluation was conducted by the manufacturer and an independent NHS site. Ct cycles of individual positives and pooled positives were determined by qRT-PCR. RESULTS: In 42 pools containing a single positive sample with Ct values ranging between 17 and 36, 41 pools (97.6 %) were found positive by the SARS-CoV-2 SAMBA II test. The false-negative pool by SAMBA was also negative by both reference methods used in this evaluation.The individual positive sample in this pool was positive by SAMBA (Orf only) and by one of the reference methods (S gene only, Ct 35) but negative by the second reference method indicating that the sample itself was very low viral load. All 78 pools containing 4 negative swabs were negative (100 % specificity). DISCUSSION: The preliminary data of the evaluation indicated a high level of performance in both sensitivity and specificity of the SAMBA II assay when used to test pools of 4 patient samples. The implementation of this pooled protocol can increase throughput and reduce cost/test when the prevalence of COVID is low.


Subject(s)
COVID-19 , SARS-CoV-2 , Diagnostic Tests, Routine , Humans , Pandemics , Sensitivity and Specificity , Specimen Handling
20.
Viruses ; 13(7)2021 07 08.
Article in English | MEDLINE | ID: covidwho-1302501

ABSTRACT

Real-time reverse transcription polymerase chain reaction (RT-qPCR) is the most sensitive and specific assay and, therefore, is the "gold standard" diagnostic method for the diagnosis of SARS-CoV-2 infection. The aim of this study was to compare and analyze the detection performance of three different commercially available SARS-CoV-2 nucleic acid detection kits: Sansure Biotech, GeneFinderTM, and TaqPathTM on 354 randomly selected samples from hospitalized COVID-19 patients. All PCR reactions were performed using the same RNA isolates and one real-time PCR machine. The final result of the three evaluated kits was not statistically different (p = 0.107), and also had a strong positive association and high Cohen's κ coefficient. In contrast, the average Ct values that refer to the ORF1ab and N gene amplification were significantly different (p < 0.001 and p < 0.001, respectively), with the lowest obtained by the TaqPathTM for the ORF1ab and by the Sansure Biotech for the N gene. The results show a high similarity in the analytical sensitivities for SARS-CoV-2 detection, which indicates that the diagnostic accuracy of the three assays is comparable. However, the SanSure Biotech kit showed a bit better diagnostic performance. Our findings suggest that the imperative for improvement should address the determination of cut-off Ct values and rapid modification of the primer sets along with the appearance of new variants.


Subject(s)
COVID-19 Nucleic Acid Testing/methods , COVID-19/virology , Reagent Kits, Diagnostic , Real-Time Polymerase Chain Reaction/methods , SARS-CoV-2/isolation & purification , COVID-19/diagnosis , COVID-19/epidemiology , Cross-Sectional Studies , Humans , RNA, Viral/genetics , RNA, Viral/isolation & purification , SARS-CoV-2/genetics , Sensitivity and Specificity , Serbia/epidemiology
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