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1.
Trop Med Infect Dis ; 7(6)2022 Jun 10.
Article in English | MEDLINE | ID: covidwho-1884360

ABSTRACT

WHO recommends surveillance for COVID-19 among travelers at Points of Entry (POE) to countries. At 13 selected POE at the Nepal-India border, between March 2021 and July 2021, we describe the screening, testing, diagnosis and isolation practices of COVID-19 amongst travelers. Those who stayed in India or elsewhere for > one day and those who did not have a negative RT-PCR result within the last 72 h of travel were tested for COVID-19 with rapid antigen diagnostic tests. Daily surveillance reports maintained at POE were used for analysis. Of 337,338 travelers screened, 69,886 (21%) were tested and 3907 (6%) were diagnosed with COVID-19. The proportions tested averaged 15% during April-May when screened numbers were high and increased to 35% in July when screened numbers had decreased. The proportions diagnosed positive peaked at 10% in April-May, but decreased to below 1% in June and July. Testing coverage varied from 0-99% in the different POE. Most COVID-19 cases were Nepalese, male, <60 years of age, migrant workers and presented with fever. Of COVID-19 cases, 32% had home-based isolation, 64% underwent community-based isolation and the remainder either went to hospital or returned to India. In conclusion, about one fifth of travelers overall were tested, with coverage varying considerably over time and among different POE. Strengthening surveillance processes at POE is needed.

2.
Diagnostics (Basel) ; 12(6)2022 Jun 04.
Article in English | MEDLINE | ID: covidwho-1884051

ABSTRACT

Coronavirus disease 2019 (COVID-19) initiated global health care challenges such as the necessity for new diagnostic tests. Diagnosis by real-time PCR remains the gold-standard method, yet economical and technical issues prohibit its use in points of care (POC) or for repetitive tests in populations. A lot of effort has been exerted in developing, using, and validating antigen-based tests (ATs). Since individual studies focus on few methodological aspects of ATs, a comparison of different tests is needed. Herein, we perform a systematic review and meta-analysis of data from articles in PubMed, medRxiv and bioRxiv. The bivariate method for meta-analysis of diagnostic tests pooling sensitivities and specificities was used. Most of the AT types for SARS-CoV-2 were lateral flow immunoassays (LFIA), fluorescence immunoassays (FIA), and chemiluminescence enzyme immunoassays (CLEIA). We identified 235 articles containing data from 220,049 individuals. All ATs using nasopharyngeal samples show better performance than those with throat saliva (72% compared to 40%). Moreover, the rapid methods LFIA and FIA show about 10% lower sensitivity compared to the laboratory-based CLEIA method (72% compared to 82%). In addition, rapid ATs show higher sensitivity in symptomatic patients compared to asymptomatic patients, suggesting that viral load is a crucial parameter for ATs performed in POCs. Finally, all methods perform with very high specificity, reaching around 99%. LFIA tests, though with moderate sensitivity, appear as the most attractive method for use in POCs and for performing seroprevalence studies.

3.
Inquiry ; 59: 469580221105354, 2022.
Article in English | MEDLINE | ID: covidwho-1879191

ABSTRACT

OBJECTIVES: Reverse transcriptase-polymerase chain reaction (RT-PCR), the reference laboratory method of confirmed SARS-CoV-2 diagnosis, though requiring equipment, is time-consuming. There is a crucial demand for rapid techniques such as antigen detection test during the pandemic. This study assessed whether a rapid antigen detection (RAD) test was an effective and essential method for the early diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during the COVID-19 pandemic. The probability of public screening at home and the application of RAD during the novel SARS-CoV-2 outbreak were also topics of interest. METHODS: A retrospective analysis based on the systemic screening for COVID-19 was conducted at Taipei City Hospital (TCH) from May 28 to June 06, 2021, the first week of outbreak in Taiwan. The results of the RAD and RT-PCR tests were collected from 5 major branches of the TCH. RESULTS: We collected a total number of 6368 cases. We found that the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy ranged from 60.5% to 78.6% (mean 66.0%), 98.2% to 99.9% (mean 99.0%), 74.4% to 97.8% (mean 82.8%), 94.0% to 98.4% (mean 97.5%), and 93.8% to 98.3% (mean 94.2%), respectively. Although the sensitivity score was not high (up to 95% or higher), the other results were satisfactory, with an accuracy of more than 93% in all branches. Furthermore, it had high specificity, PPV, NPV, and accuracy. CONCLUSION: We concluded that RAD could be a quick and feasible method to identify individuals infected with SARS-CoV-2 from non-contagious individuals during the COVID-19 outbreak. A RAD test was an effective and essential method for the early diagnosis of SARS-CoV-2 during the COVID-19 pandemic.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19 Testing , Humans , Pandemics , Retrospective Studies , Sensitivity and Specificity
4.
J Korean Med Sci ; 37(21): e168, 2022 May 30.
Article in English | MEDLINE | ID: covidwho-1875391

ABSTRACT

Despite the accuracy of nucleic acid amplification tests (NAATs), rapid antigen tests (RATs) for severe acute respiratory syndrome coronavirus-2 are widely used as point-of-care tests. A total of 282 pairs of reverse transcription-polymerase chain reaction and Standard Q COVID-19 Ag tests were serially conducted for 68 patients every 3-4 days until their discharge. Through a field evaluation of RATs using direct nasopharyngeal swabs, the sensitivities were 84.6% and 87.3% for E and RNA-dependent RNA polymerase (RdRp) genes, respectively, for specimens with cycle thresholds (Cts) < 25. The Ct values of E and RdRp genes for 95% detection rates by RATs were 16.9 and 18.1, respectively. The sensitivity of RAT was 48.4% after the onset of symptoms, which was not sufficient. RAT positivity gradually decreased with increased time after symptom onset and had continuously lower sensitivity than NAATs.


Subject(s)
COVID-19 Testing , COVID-19 , SARS-CoV-2 , Antigens, Viral , COVID-19/diagnosis , COVID-19 Testing/methods , Humans , Nasopharynx , RNA-Dependent RNA Polymerase , SARS-CoV-2/isolation & purification , Sensitivity and Specificity
5.
Dent Mater ; 38(6): e155-e159, 2022 Jun.
Article in English | MEDLINE | ID: covidwho-1873002

ABSTRACT

OBJECTIVE: Fast and reliable detection of infection is a key to control the SARS-CoV-2 pandemic. Lateral flow antigen tests (LFATs) are inexpensive, easy to use, but have to be verified, as they are rather unspecific and can produce both, false positive and false negative results. Our objective was to combine the speed of LFAT for SARS-CoV-2 with the reliability of qPCR tests. METHODS: A serial dilution of a patient sample positive for SARS-CoV-2 was prepared and added to LFAT wells from two manufacturers. After evaluation, the devices were opened, the strips removed and extracted in a solution. Amplification was performed using point of care PCR systems (cobas® Liat®, ID NOW™) or on a LightCycler after extraction by MagNAPure 96. RESULTS: The nucleic acid amplification systems yielded higher sensitivity to LFAT. Thus, all samples determined positive by LFAT from the serial dilution were also positive in the subsequent amplification reactions. Sensitivity using extracted eluates was 10-100 times higher. SIGNIFICANCE: The usage of LFAT is highly recommended for single samples in emergency dental or emergency clinical settings, for smaller cohorts, or even for larger population screening, as it is inexpensive and fast. Positive results can be conveniently verified directly from the test devices using either point of care test equipment or more complex laboratory equipment thus making a major impact on efficient management of infections and isolations.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/diagnosis , Humans , Real-Time Polymerase Chain Reaction , Reproducibility of Results , Sensitivity and Specificity
6.
J Med Virol ; 2022 Jun 02.
Article in English | MEDLINE | ID: covidwho-1872245

ABSTRACT

The severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) Omicron was classified as a variant of concern in November 2021. The sublineage BA.2 spreads rapidly worldwide. Currently, there is a lack of data for the parallel comparison of Rapid Antigen Test (RAT) Kits to detect SARS-CoV-2 Omicron BA.2. We evaluated the analytical sensitivity of 12 RAT kits to detect Omicron BA.2 in the present study. Analytical sensitivity was determined by means of the limit of detection (LOD). We prepared a dilution set using a respiratory specimen collected from a COVID-19 patient infected by Omicron BA.2. The reverse transcription-polymerase chain reaction was used as a reference method. The LOD results showed that all 12 RAT kits had comparable analytical sensitivity to detect Omicron BA.2. The RAT kits selected in the current study may be used for the first-line screening of the rapid spreading Omicron BA.2.

7.
J Nippon Med Sch ; 2022 May 30.
Article in English | MEDLINE | ID: covidwho-1869136

ABSTRACT

BACKGROUND: Nasopharyngeal swabs (NPS) are generally used as specimen samples for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen qualitative tests. The principle of reaction to the antigen protein is the same when saliva is used. Saliva samples have been reported to be as accurate as NPS in real-time reverse transcription quantitative polymerase chain reaction (RT-qPCR) to identify SARS-CoV-2. Unlike NPS collection, self-collected saliva does not expose healthcare workers to the risk of infection. In this study, we evaluated the feasibility of using saliva samples for the SARS-CoV-2 antigen qualitative test (TA2107SA), a test under development by TAUNS Laboratories, Inc. METHODS: Saliva sample from patients with or suspected of having COVID-19 infection were collected and analyzed. The sensitivity, specificity and concordance index of the antigen qualitative test were calculated using RT-qPCR test as a reference. RESULTS: Saliva samples were collected from 105 patients. The mean period from onset to specimen collection was 5.7 days. The mean cycle threshold (Ct) value of RT-qPCR was 31.3. The sensitivity, specificity, and concordance index were 70.7%, 100%, and 0.85, respectively. In 33 patients with Ct values <30, both RT-qPCR and antigen tests were positive. The sensitivity of the TA2107SA SARS-CoV-2 antigen qualitative test using saliva was slightly lower than that of the conventional antigen qualitative test using NPS samples in the same patient. CONCLUSION: The antigen qualitative tests for SARS-CoV-2 using saliva samples could be an alternative option in a pandemic period.

8.
Infect Dis (Lond) ; : 1-7, 2022 May 30.
Article in English | MEDLINE | ID: covidwho-1868224

ABSTRACT

BACKGROUND: Current method for diagnosis of SARS-CoV-2 infection is an RT-PCR test on the nasopharyngeal or oropharyngeal swab. Rapid diagnosis is essential for containing viral spread and triage of symptomatic patients presenting to hospital ER departments. As a faster alternative to RT-PCR, we evaluated a SARS-Cov-2 Rapid Antigen test in symptomatic patients presenting to hospital ER departments. METHODS: We evaluated the diagnostic performance of the Roche SARS-CoV-2 Rapid Antigen test (SD Biosensor) for detection of SARS-CoV-2 compared to RT-PCR. RESULTS: Our study showed inferior performance of the SARS-CoV-2 Rapid Antigen test for detection of SARS-CoV-2. Firstly, because of the lack of specificity, which is potentially life-threatening due to the association of nosocomial-acquired SARS-CoV-2 infection. Secondly, with a sensitivity of 45.5%, it is impossible to rule out SARS-CoV-2 infection, resulting in reflex PCR-testing. Comparison of viral load in RT-PCR positive samples with corresponding antigen results showed a significant difference between antigen positive and negative samples. COVID-19 infection will not be detected in patients admitted to the hospital in an early or late phase, typically associated with low viral loads. Sensitivity increases when testing within 5-7 symptomatic days, but the implementation of this cut-off is impractical in ER settings. However, diagnostic performance is better to detect high viral load (> = 5 log10 copies/mL) linked with contagiousness. CONCLUSION: Our study showed inferior performance of the Roche SARS-CoV-2 Rapid Antigen test (SD Biosensor) for detection of SARS-CoV-2 which limits its use as a diagnostic gatekeeper in ER departments, but is able to differentiate contagious individuals.

9.
Front Public Health ; 10: 816406, 2022.
Article in English | MEDLINE | ID: covidwho-1865467

ABSTRACT

Background: The World Health Organization has promoted preventive measures for reducing the impact of the pandemic. One of these measures was tests in origin for travelers. Testing strategies for COVID-19 facilitate the overall public health response to the pandemic and contributes to minimize the infection among the population COVID-19. Goal: In this work, we assess the efficiency of diagnostic testing of incoming travelers in the Canary Islands, Spain, during a period of 4 months, with a focus on the economic impact for the regional government. We study the cost-benefit of this measure as well as the potential influence on the number of positive cases in the population. Methods: We processed the real data in the Canary Islands of pre-flight PCR and antigen tests that were required to the residents when traveling back to the Canaries from anywhere in Spain in a period of 4 months, from 14 December, 2020 to 4 April, 2021. As a result, we calculated the economic impact of doing those tests and compare them with the estimated costs of passengers under the hypothesis of entering the islands without testing. The cost-benefit was obtained for different scenarios, where the incoming passengers generated hospitalization and intensive care unit (ICU) costs directly and via transmissions. Results: The incoming testing funded by the government, if applied during the bad evolution of the pandemic with 1.2 ratio of transmission, clearly saved money to the public health system. In addition to the economic impact of this measure, we estimated the potential influence on the number of positive cases in the population according to different scenarios of the propagation of the pandemic. At the beginning of February 2021, the savings were about €130.551,47, with a 95% confidence interval (CI) of €24.677,94-236.425,00. By the end of April 2021, the savings were above €2,000,000 (€2.284.788,50 on average and 95% CI of €2.092.914,84-2.476.662,16) and the savings increased as the pandemic evolved. At the end of the period, the savings were twice the expenses. Conclusions: Testing in origin has proved to be a good measure that helped to mitigate COVID-19 spread among regions. Our results confirm that the free PCR or rapid antigen tests produce relevant savings to the public budget. We studied 61.990 reported data during 2020 and 2021 from the travelers from national flights, against 346.449 of total incoming travelers to the Canary Islands in this period. The measure pursued by the Government of the Canary Islands of providing free tests for residents showed a clear benefit for both, limiting the propagation of COVID-19 and reducing the costs of the hospitalizations and ICU admissions. It should be noted that the free testing measure in this period was before starting the vaccination campaigns. As measure of public health in the airports, testing helped to control and make the mobility of travelers secure.


Subject(s)
COVID-19 , COVID-19/diagnosis , COVID-19/epidemiology , Cost-Benefit Analysis , Humans , Pandemics/prevention & control , Spain/epidemiology , Travel
10.
Influenza Other Respir Viruses ; 2022 May 26.
Article in English | MEDLINE | ID: covidwho-1865100

ABSTRACT

OBJECTIVE: The objective of this study is to assess the utility of a nucleic acid amplification test-based approach to shorten isolation of healthcare workers (HCWs) with COVID-19 in the setting of the highly transmissible omicron variant. METHODS: Between December 24, 2021, and January 5, 2022, HCWs who tested positive for SARS-CoV-2 were retested with PCR at least 5 days since onset of symptoms. RESULTS: Forty-six sequential fully COVID-19 vaccinated HCWs who had tested positive for SARS-CoV-2 underwent follow-up testing. All the samples were confirmed as omicron variants and only four (8.7%) were negative in the follow-up test performed at a median of 6 (range 5-12) since onset of symptoms. CONCLUSIONS: Implementation of a test-based strategy is logistically challenging, increases costs, and did not lead to shorter isolation in our institution.

11.
Decision Science Letters ; 11(3):347-356, 2022.
Article in English | Scopus | ID: covidwho-1863175

ABSTRACT

After the outbreak of COVID-19, Taiwan has implemented rigorous border control and taken specific measures such as virus detection, contact tracing, and quarantine since 2020. Its epidemic prevention performance has been quite outstanding. Even in May 2021, when the epidemic situation worsens, the people in Taiwan fully cooperate with the government’s control measures so as to successfully alleviate and control the epidemic in less than three months. Among them, the detection policy has played a pivotal role. We analyze and discuss the false positive and false negative problems from rapid antigen and PCR detection in the screening policy as well as the timing of using these two instruments. This paper provides theoretical verification of the appropriateness of screening policy in Taiwan, offering a few feasible suggestions for related policies in other countries or regions at different stages of this and other potential epidemics. © 2022 by the authors;licensee Growing Science, Canada.

12.
Braz J Microbiol ; 2022 Apr 21.
Article in English | MEDLINE | ID: covidwho-1859206

ABSTRACT

The number of SARS-CoV-2 detection tests requested to the laboratories has dramatically increased together with an urgent need to release reliable responses in a very short time. The two options taken into consideration and analyzed in the current study were the point-of-care test (POCT) based on the nucleic acid amplification test (NAAT) and the Antigen (Ag) rapid test. The POCT-NAAT-based assay was compared with a rapid antigen test of nasopharyngeal swab samples. If the specimen tested positive, it was followed by viral load quantification and by the functional assessment of the residual infectivity. When the initial cycle threshold (Ct) was below 20 (100%), and in the range of 20-25 (92%) and of 25-30 (88%), a great concordance between the POCT-NAAT and the Ag test was observed. Moreover, the positivity of the antigen test was well correlated to a successful infection in vitro (78%), with greater concordance when the initial Ct below 20 or above 35 (100%) and in the range 20-25 (83%). Our findings showed that most of the swabs which tested positive using the antigen test were able to infect the cells in vitro, suggesting that probably only these samples hold residual infectivity and therefore an increased risk of virus transmission at the moment of being tested.

13.
Strojniski Vestnik-Journal of Mechanical Engineering ; 68(4):240-251, 2022.
Article in English | Web of Science | ID: covidwho-1856136

ABSTRACT

During the corona virus (COVID-19) pandemic, there was a sharp increase in the need for diagnostic tests that could detect the presence of SARS-CoV-2 virus or its antibodies quickly and reliably. An important type in the group of diagnostic tests are rapid antigen lateral flow immuno-assay (LFIA) tests, which operate on the immuno-chromatographic principle with the lateral flow of analyte. Clinical practice in the last year has shown that such diagnostic tests can be effective in preventing the spread of the SARS-CoV-2 virus. The development, and, thus, the production of the rapid antigen LFIA tests, is influenced by a number of factors that determine their sensitivity and accuracy indirectly. These factors are directly dependent on the type of antibody produced, which is formed as an immune response when infected with the virus. The production of the rapid antigen LFIA tests is associated with the appropriate selection of basic components that determine the type and quality of these tests. The basic components include: substrates and membranes, antigens, antibody labels and compatible buffers. The correct choice of membranes and their materials is crucial to compiling an effective rapid antigen LFIA test. This study therefore presents a comparative analysis of four commercially available SARS-CoV-2-rapid LFIA tests using state-of-theart characterisation techniques scanning electron microscopy (SEM), inductively coupled plasma-optical emission spectrometry (ICP-OES), environmental scanning electron microscope / energy-dispersive X-ray spectroscopy (ESEM/EDX), Fourier-transform infrared spectroscopy / attenuated total reflection (FTIR/ATR) for the individual components. The obtained results were the starting point for the development and assembling of our own rapid antigen LFIA test based on gold nanoparticles as antibody labels.

14.
Infection ; 2022 May 20.
Article in English | MEDLINE | ID: covidwho-1850466

ABSTRACT

PURPOSE: Omicron is rapidly spreading as a new SARS-CoV-2 variant of concern (VOC). The question whether this new variant has an impact on SARS-CoV-2 rapid antigen test (RAT) performance is of utmost importance. To obtain an initial estimate regarding differences of RATs in detecting omicron and delta, seven commonly used SARS-CoV-2 RATs from different manufacturers were analysed using cell culture supernatants and clinical specimens. METHODS: For this purpose, cell culture-expanded omicron and delta preparations were serially diluted in Dulbecco's modified Eagle's Medium (DMEM) and the Limit of Detection (LoD) for both VOCs was determined. Additionally, clinical specimens stored in viral transport media or saline (n = 51) were investigated to complement in vitro results with cell culture supernatants. Ct values and RNA concentrations were determined via quantitative reverse transcription polymerase chain reaction (RT-qPCR). RESULTS: The in vitro determination of the LoD showed no obvious differences in detection of omicron and delta for the RATs examined. The LoD in this study was at a dilution level of 1:1,000 (corresponding to 3.0-5.6 × 106 RNA copies/mL) for tests I-V and at a dilution level of 1:100 (corresponding to 3.7-4.9 × 107 RNA copies/mL) for tests VI and VII. Based on clinical specimens, no obvious differences were observed between RAT positivity rates when comparing omicron to delta in this study setting. Overall positivity rates varied between manufacturers with 30-81% for omicron and 42-71% for delta. Test VII was only conducted in vitro with cell culture supernatants for feasibility reasons. In the range of Ct < 23, positivity rates were 50-100% for omicron and 67-93% for delta. CONCLUSION: In this study, RATs from various manufacturers were investigated, which displayed no obvious differences in terms of analytical LoD in vitro and RAT positivity rates based on clinical samples comparing the VOCs omicron and delta. However, differences between tests produced by various manufacturers were detected. In terms of clinical samples, a focus of this study was on specimens with high virus concentrations. Further systematic, clinical and laboratory studies utilizing large datasets are urgently needed to confirm reliable performance in terms of sensitivity and specificity for all individual RATs and SARS-CoV-2 variants.

15.
Diagnostics (Basel) ; 12(5)2022 Apr 21.
Article in English | MEDLINE | ID: covidwho-1847278

ABSTRACT

Due to the prevailing ambiguity regarding the performance of rapid antigen tests (RATs) for B.1.1.529 (Omicron) variant diagnosis, a commercial RAT was evaluated in the emergency ward of a general hospital in Larissa, Central Greece. The sampling and the evaluation were repeated twice by different personnel. Discordance between the two samplings was observed regarding the sensitivity (47.5%, 95% CI: 39.0-56.1 vs. 78.6%, 95% CI: 69.1-86.2) and specificity (93.8%, 95% CI: 86.0-97.9 vs. 100.0%, 95% CI: 93.3-100.0) of the RAT. Furthermore, the test displayed slightly lower sensitivity (78.6% vs. 85.5%, 95% CI: 79.1-90.5) compared to its initial evaluation that was conducted by our team when the B.1.1.7 (Alpha) variant was dominant.

16.
Front Public Health ; 10: 840984, 2022.
Article in English | MEDLINE | ID: covidwho-1847237

ABSTRACT

Background: As the COVID-19 pandemic resurges affecting large numbers of patients, rapid, and accurate diagnosis using point-of-care tests is very important. Objectives: To evaluate the NG-Test® SARS-CoV-2 Ag (NG-Test) immunoassay for qualitative detection of SARS-CoV-2 antigen in nasopharyngeal (NP) and oropharyngeal (OP) samples compared with RT-PCR, in patients attending the Emergencies of an academic referral hospital. Methods: All adult ambulatory patients presenting to the Emergencies of "Attikon" University hospital (Athens, Greece) within three consecutive hours per day between December 2020 and March 2021 and for whom SARS-CoV-2 PCR testing was requested were included. Two NP and one OP samples obtained from each participant were analyzed to determine the diagnostic performance [sensitivity, specificity, positive/negative predictive values (PPV/NPV)] of the NG-Test (NP/OP swabs) in comparison to the reference RT-PCR (NP swab). Results: Overall, 134/263 (51%) patients tested were RT-PCR positive, whereof 108 (overall sensitivity 81%, 95% CI 73-87%) were NP NG-Test positive (PPV 99%, NPV 83%) and 68 (overall sensitivity 51%, 95% CI 42-59%) were OP NG-Test positive (PPV 100%, NPV 66%). The test's specificity (95% CI) was 99% (95-100%) and 100% (96-100%) for NP and OP swabs, respectively. The assay's sensitivity (95% CI) for high viral load (Ct ≤25) was 99% (92-100%) and 71% (60-81%) for NP and OP swabs, respectively. Conclusions: NG-Test using NP swabs detected almost all patients with high viral loads, showing satisfactory performance as a point-of-care test for NP samples obtained from patients with acute infection.


Subject(s)
COVID-19 , SARS-CoV-2 , Adult , Antigens, Viral , COVID-19/diagnosis , Emergencies , Emergency Service, Hospital , Hospitals , Humans , Pandemics , Referral and Consultation , Sensitivity and Specificity
17.
Methods Mol Biol ; 2452: 45-62, 2022.
Article in English | MEDLINE | ID: covidwho-1844259

ABSTRACT

Currently, the most accurate way to diagnose an active SARS-CoV-2 (COVID-19) infection is through detection of viral RNA using reverse transcription polymerase chain reaction (RT-PCR) test. While RT-PCR tests are the most sensitive for identifying infection, there are significant limitations, such as global access to sufficient test kits, turnaround times (TAT) from specimen collection to test result is often greater than 24 h and the need for skilled operators in accredited laboratories requiring specialized equipment. A rapid test performed at the point of care (POC) could provide a result within an approximate time of 30 min post specimen collection, be performed by a health care worker and comprise a simple workflow, improving both turnaround time and potentially decreasing costs (e.g., transport, cold-chain, skilled laboratory staff, complex equipment). Determining the performance of SARS-CoV-2 RT-PCR tests is, however, easier to assess than antigen-based POCT, as residual clinical specimens (swabs in universal transport media [UTM]) are readily available in laboratory environments, and do not require patient informed consent. Evaluating the performance of POCT requires informed-consent driven studies, with patients required to provide a standard of care specimen as well as study evaluation specimens, which is often not acceptable as nasopharyngeal swabbing can be invasive, clinical field trials are costly and time consuming. Many institutions and regulatory bodies also require preliminary data prior to use in field settings. Therefore, we have developed a method to determine the performance of antigen based POCT that can be used by implementers in national healthcare programs, regulators and rapid test developers. The method investigates both quantitative and qualitative parameters, with the latter providing insights into the capability for implementation and national program uptake.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/diagnosis , COVID-19 Testing , Humans , Nasopharynx , Point-of-Care Testing , SARS-CoV-2/genetics , Sensitivity and Specificity
18.
Indian J Ophthalmol ; 70(5): 1761-1765, 2022 05.
Article in English | MEDLINE | ID: covidwho-1835130

ABSTRACT

Purpose: To assess the rapid antigen test (RAT) against the gold standard reverse transcription-polymerase chain reaction (RT-PCR) to screen COVID-19 infection in asymptomatic patients undergoing ophthalmic procedures. Methods: This was a retrospective hospital-based study. Point-of-care (PoC) RAT was performed using nasopharyngeal swab, while RT-PCR for SARS-CoV-2 viral RNA was performed using both nasopharyngeal and throat swabs. Results: A total of 629 patients were tested for SARS-CoV-2 by using both RAT and RT-PCR. Only one patient had tested positive for SARS-CoV-2 with both RAT and RT-PCR, while two patients had tested positive with RT-PCR after an initial negative RAT. The positivity rate for RAT was 0.15% (1/629), and that for RT-PCR was 0.47%. Percent agreement or proportion of agreement observed between the two tests was 99.68%, while Cohen's kappa coefficient value was 0.49. The sensitivity of RAT in comparison to RT-PCR was 33.33%, specificity was 100%, positive predictive value was 100%, and negative predictive value was 99.68%. Conclusion: The sensitivity and Cohen's kappa coefficient in our study were low but that can be attributed to the overall low positivity rates with both RAT and RT-PCR. However, percent agreement observed between the two tests was very high. Therefore, we recommend initial screening of all the patients for COVID-19 symptoms followed by RAT before performing any ophthalmic surgical procedure to ensure the safety of the health care professionals as well as the patients.


Subject(s)
COVID-19 , Ophthalmology , COVID-19/diagnosis , COVID-19/epidemiology , Humans , Pandemics , Retrospective Studies , Reverse Transcriptase Polymerase Chain Reaction , Reverse Transcription , SARS-CoV-2
19.
Front Public Health ; 10: 852083, 2022.
Article in English | MEDLINE | ID: covidwho-1834649

ABSTRACT

Polymerase chain reaction (PCR) remains the gold standard in disease diagnostics due to its extreme sensitivity and specificity. However, PCR tests are expensive and complex, require skilled personnel and specialized equipment to conduct the tests, and have long turnaround times. On the other hand, lateral flow immunoassay-based antigen tests are rapid, relatively inexpensive, and can be performed by untrained personnel at the point of care or even in the home. However, rapid antigen tests are less sensitive than PCR since they lack the inherent target amplification of PCR. It has been argued that rapid antigen tests are better indicators of infection in public health decision-making processes to test, trace, and isolate infected people to curtail further transmission. Hence, there is a critical need to increase the sensitivity of rapid antigen tests and create innovative solutions to achieve that goal. Herein, we report the development of a low-cost diagnostic platform, enabling rapid detection of SARS-CoV-2 under field or at-home conditions. This platform (Halo™) is a small, highly accurate, consumer-friendly diagnostic reader paired with fluorescently labeled lateral flow assays and custom software for collection and reporting of results. The focus of this study is to compare the analytical performance of HaloTM against comparable tests that use either colloidal gold nanoparticles or fluorescence-based reporters in simulated nasal matrix and not in clinical samples. Live virus data has demonstrated limit of detection performance of 1.9 TCID50/test in simulated nasal matrix for the delta variant, suggesting that single-assay detection of asymptomatic SARS-CoV-2 infections may be feasible. Performance of the system against all tested SARS CoV-2 virus variants showed comparable sensitivities indicating mutations in SARS-CoV-2 variants do not negatively impact the assay.


Subject(s)
COVID-19 , Metal Nanoparticles , COVID-19/diagnosis , Gold , Humans , Proof of Concept Study , SARS-CoV-2
20.
JMIR Res Protoc ; 11(5): e35706, 2022 May 04.
Article in English | MEDLINE | ID: covidwho-1834187

ABSTRACT

BACKGROUND: The SARS-CoV-2 pandemic has resulted in an unprecedented level of worldwide testing for epidemiologic and diagnostic purposes, and due to the extreme need for tests, the gold-standard Reverse Transcription Polymerase Chain Reaction (RT-PCR) testing capacity has been unable to meet the overall worldwide testing demand. Consequently, although the current literature has shown the sensitivity of rapid antigen tests (RATs) to be inferior to RT-PCR, RATs have been implemented on a large scale without solid data on performance. OBJECTIVE: This study will compare analytical and clinical sensitivities and specificities of 50 lateral flow- or laboratory-based RATs and 3 strand invasion-based amplification (SIBA)-RT-PCR tests from 30 manufacturers to RT-PCR testing of samples obtained from the deep oropharynx. In addition, the study will compare sensitivities and specificities of the included RATs as well as RT-PCR on clinical samples obtained from the deep oropharynx, the anterior nasal cavity, saliva, the deep nasopharynx, and expired air to RT-PCR on deep oropharyngeal samples. METHODS: In the prospective part of the study, 200 individuals found SARS-CoV-2 positive and 200 individuals found SARS-CoV-2 negative by routine RT-PCR testing will be retested with each RAT, applying RT-PCR as the reference method. In the retrospective part of the study, 304 deep oropharyngeal cavity swabs divided into 4 groups based on RT-PCR quantification cycle (Cq) levels will be tested with each RAT. RESULTS: The results will be reported in several papers with different aims. The first paper will report retrospective (analytical sensitivity, overall and stratified into different Cq range groups) and prospective (clinical sensitivity) data for RATs, with RT-PCR as the reference method. The second paper will report results for RAT based on anatomical sampling location. The third paper will compare different anatomical sampling locations by RT-PCR testing. The fourth paper will focus on RATs that rely on central laboratory testing. Tests from 4 different manufacturers will be compared for analytical performance data on retrospective deep oropharyngeal swab samples. The fifth paper will report the results of 4 RATs applied both as professional use and as self-tests. The last paper will report the results from 2 breath tests in the study. A comparison of sensitivity and specificity between RATs will be conducted using the McNemar test for paired samples and the chi-squared test for unpaired samples. Comparison of the positive predictive value (PPV) and negative predictive value (NPV) between RATs will be performed by the bootstrap test, and 95% CIs for sensitivity, specificity, PPV, and NPV will be calculated as bootstrap CIs. CONCLUSIONS: The study will compare the sensitivities of a large number of RATs for SARS-CoV-2 to with those of RT-PCR and will address whether lateral flow-based RATs differ significantly from laboratory-based RATs. The anatomical test locations for both RATs and RT-PCR will also be compared. TRIAL REGISTRATION: ClinicalTrials.gov NCT04913116; https://clinicaltrials.gov/ct2/show/NCT04913116. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/35706.

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