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The practical application of the reverse transcription loop-mediated isothermal amplification (RT-LAMP) technique has been confirmed in diagnosing different viral infections. Nevertheless, its accuracy in identifying SARS-CoV-2, particularly in practical clinical situations, has not been thoroughly investigated. This study aims to investigate the sensitivity and specificity of the Elva Diagnostic SARS-CoV-2 Saliva Nucleic Acid Test Kit, utilizing the RT-LAMP and Rapid Antigen Test (RAT) methods for in vitro diagnostic testing, compared to the real-time quantitative polymerase chain reaction (RT-qPCR) method throughout the progression of COVID-19. Method: This study employed an analytical observational diagnostic test at Dr. Soetomo Regional Public Hospital, Surabaya, from March 2022 to May 2022. This research involved 54 samples of saliva and nasopharyngeal swabs obtained from 36 patients confirmed positive for COVID-19 and 18 samples from subjects not confirmed to have COVID-19, tested using the RT-qPCR method. The diagnostic performance of both the RT-LAMP and RAT methods was assessed by calculating their sensitivity and specificity in comparison to RT-qPCR, beginning from the time the patient was confirmed positive for COVID-19. The suitability of each method was analyzed using Cohen’s kappa. The nucleocapsid (N) protein gene from SARS-CoV-2 RNA was detected with RT-LAMP and RAT test kits which showed incompatibilities with the RT-qPCR method (p value 0.308). The positive and negative results with the RT-LAMP and RAT method examinations were similar in number compared to the RT-qPCR method, where the positive results in the RT-LAMP and RAT methods were 2 subjects and the negative results were 52 subjects. Based on the results, only 2 confirmed cases had positive results with RT-LAMP and RAT, which means the sensitivity of both tests is only 5.5% and both are poor screening tests for patients suspected of having COVID-19. In addition, the specificity of RT-qPCR as the gold standard examination method for diagnosing COVID-19 cannot be replaced by the RT-LAMP and RAT methods.

Background: The COVID‐19 pandemic underscored the need for rapid and accurate diagnostic tools. In August 2020, the Abbott BinaxNOW COVID‐19 Antigen Card test became available as a timely and affordable alternative for SARS‐CoV‐2 molecular testing, but its performance may vary due to factors including timing and symptomatology. This study evaluates BinaxNOW diagnostic performance in diverse epidemiological contexts. Methods: Using RT‐PCR as reference, we assessed performance of the BinaxNOW COVID‐19 test for SARS‐CoV‐2 detection in anterior nasal swabs from participants of two studies in Puerto Rico from December 2020 to May 2023. Test performance was assessed by days post symptom onset, collection strategy, vaccination status, symptomatology, repeated testing, and RT‐PCR cycle threshold (Ct) values. Results: BinaxNOW demonstrated an overall sensitivity of 84.1% and specificity of 98.8%. Sensitivity peaked within 1–6 days after symptom onset (93.2%) and was higher for symptomatic (86.3%) than asymptomatic (67.3%) participants. Sensitivity declined over the course of infection, dropping from 96.3% in the initial test to 48.4% in testing performed 7–14 days later. BinaxNOW showed 99.5% sensitivity in participants with low Ct values (≤ 25) but lower sensitivity (18.2%) for participants with higher Cts (36–40). Conclusions: BinaxNOW demonstrated high sensitivity and specificity, particularly in early‐stage infections and symptomatic participants. In situations where test sensitivity is crucial for clinical decision‐making, nucleic acid amplification tests are preferred. These findings highlight the importance of considering clinical and epidemiological context when interpreting test results and emphasize the need for ongoing research to adapt testing strategies to emerging SARS‐CoV‐2 variants. [ABSTRACT FROM AUTHOR]

Background Understanding changes in diagnostic performance after symptom onset and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exposure within different populations is crucial to guide the use of diagnostics for SARS-CoV-2. Methods The Test Us at Home study was a longitudinal cohort study that enrolled individuals across the United States between October 2021 and February 2022. Participants performed paired antigen-detection rapid diagnostic tests (Ag-RDTs) and reverse-transcriptase polymerase chain reaction (RT-PCR) tests at home every 48 hours for 15 days and self-reported symptoms and known coronavirus disease 2019 exposures immediately before testing. The percent positivity for Ag-RDTs and RT-PCR tests was calculated each day after symptom onset and exposure and stratified by vaccination status, variant, age category, and sex. Results The highest percent positivity occurred 2 days after symptom onset (RT-PCR, 91.2%; Ag-RDT, 71.1%) and 6 days after exposure (RT-PCR, 91.8%; Ag-RDT, 86.2%). RT-PCR and Ag-RDT performance did not differ by vaccination status, variant, age category, or sex. The percent positivity for Ag-RDTs was lower among exposed, asymptomatic than among symptomatic individuals (37.5% (95% confidence interval [CI], 13.7%–69.4%) vs 90.3% (75.1%–96.7%). Cumulatively, Ag-RDTs detected 84.9% (95% CI, 78.2%–89.8%) of infections within 4 days of symptom onset. For exposed participants, Ag-RDTs detected 94.0% (95% CI, 86.7%–97.4%) of RT-PCR–confirmed infections within 6 days of exposure. Conclusions The percent positivity for Ag-RDTs and RT-PCR tests was highest 2 days after symptom onset and 6 days after exposure, and performance increased with serial testing. The percent positivity of Ag-RDTs was lowest among asymptomatic individuals but did not differ by sex, variant, vaccination status, or age category. [ABSTRACT FROM AUTHOR]

The practical application of the reverse transcription loop-mediated isothermal amplification (RT-LAMP) technique has been confirmed in diagnosing different viral infections. Nevertheless, its accuracy in identifying SARS-CoV-2, particularly in practical clinical situations, has not been thoroughly investigated. This study aims to investigate the sensitivity and specificity of the Elva Diagnostic SARS-CoV-2 Saliva Nucleic Acid Test Kit, utilizing the RT-LAMP and Rapid Antigen Test (RAT) methods for in vitro diagnostic testing, compared to the real-time quantitative polymerase chain reaction (RT-qPCR) method throughout the progression of COVID-19. Method: This study employed an analytical observational diagnostic test at Dr. Soetomo Regional Public Hospital, Surabaya, from March 2022 to May 2022. This research involved 54 samples of saliva and nasopharyngeal swabs obtained from 36 patients confirmed positive for COVID-19 and 18 samples from subjects not confirmed to have COVID-19, tested using the RT-qPCR method. The diagnostic performance of both the RT-LAMP and RAT methods was assessed by calculating their sensitivity and specificity in comparison to RT-qPCR, beginning from the time the patient was confirmed positive for COVID-19. The suitability of each method was analyzed using Cohen’s kappa. The nucleocapsid (N) protein gene from SARS-CoV-2 RNA was detected with RT-LAMP and RAT test kits which showed incompatibilities with the RT-qPCR method (p value 0.308). The positive and negative results with the RT-LAMP and RAT method examinations were similar in number compared to the RT-qPCR method, where the positive results in the RT-LAMP and RAT methods were 2 subjects and the negative results were 52 subjects. Based on the results, only 2 confirmed cases had positive results with RT-LAMP and RAT, which means the sensitivity of both tests is only 5.5% and both are poor screening tests for patients suspected of having COVID-19. In addition, the specificity of RT-qPCR as the gold standard examination method for diagnosing COVID-19 cannot be replaced by the RT-LAMP and RAT methods. [ABSTRACT FROM AUTHOR]

Background: Community infections of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have increased rapidly since the emergence of the Omicron strain. During the eighth and ninth pandemic waves—when movement restrictions in the community were eased—the all-case registration system was changed, and the actual status of infection became uncertain. Methods: We conducted regular rapid antigen tests (R-RATs) once or twice a week as self-testing to examine the actual state of coronavirus disease (COVID-19) diagnosis among healthcare employees. Results: Overall, 320 (1.42/day) and 299 (1.76/day) employees were infected in the eighth and ninth pandemic waves. During both periods, 59/263 doctors (22.4%), 335/806 nurses (41.6%), 92/194 administrative employees (47.4%), and 129/218 clinical laboratory technicians (59.2%) were infected. In the eighth wave, 56 of 195 employees were infected through close contact; in the ninth wave, 26 of 62 employees were infected. No significant difference was observed in the number of vaccinations between infected and non-infected employees. The positivity rate of R-RATs was 0.41% and 0.45% in the eighth and ninth waves. R-RATs detected infection in 212 and 229 employees during the eighth and ninth waves, respectively; the ratio of R-RAT-detected positive employees to those who reported infection was significantly higher during the ninth wave (odds ratio: 1.67, 95% confidence interval: 1.17–2.37, p < 0.001). Conclusions: The number of infected healthcare employees remained high during the eighth and ninth pandemic waves in Japan. The R-RAT is considered effective for detecting mild or asymptomatic COVID-19 at an early stage and at a high rate in healthcare employees. [ABSTRACT FROM AUTHOR]

BackgroundThe aim of this study was to investigate the accuracy of self-tested SARS-CoV-2 rapid antigen tests.MethodsDatabases of Pubmed, Embase, and Cochrane Library were searched for original studies investigating accuracy of self-tested SARS-CoV-2 rapid antigen tests, with RT-PCR as “gold standard.”ResultsForty-five eligible studies were found after database searching and screening using pre-defined criteria. The accuracy results from 50,897 suspected COVID-19 patients were pooled, and the overall sensitivity, specificity and diagnostic odds ratio were 0.77, 1.00, and 625.95, respectively. Subgroup analysis showed higher sensitivity of rapid antigen tests in subgroups of Abbott Panbio, self-collected nasal swab samples, and use of nasopharyngeal or oropharyngeal swab and lower Ct cutoff value in RT-PCR.ConclusionFully self-performed SARS-CoV-2 rapid antigen tests showed overall high accuracy compared to “gold standard,” and are reliable surrogates for the standard test of COVID-19 using nasopharyngeal or oropharyngeal samples and RT-PCR.

Abstract Background While numerous studies have evaluated the real-world performance of rapid antigen tests (RATs), data on the effect of Omicron sublineages such as XBB and reinfections on RAT performance is limited. We assessed the performance of RATs and factors associated with RAT-negative results among individuals who tested SARS-CoV-2-positive by reverse transcription-polymerase chain reaction (RT-PCR). Methods We conducted a retrospective study among Singapore residents who underwent testing for SARS-CoV-2 with RAT (Acon Flowflex or SD Biosensor) and RT-PCR in the same clinical encounter between 9 May 2022 and 21 November 2022. RT-PCR served as a reference standard for RAT performance. Logistic regression was used to estimate the odds ratios (OR) of factors associated with negative RAT results among RT-PCR-positive cases. Results Of 8,620 clinical encounters analysed, 3,519 (40.8%) were SARS-CoV-2-positive on RT-PCR. Overall sensitivity and specificity of RAT was 84.6% (95% CI 83.3–85.7%) and 99.4% (95% CI 99.1–99.6%) respectively. Acon Flowflex consistently achieved higher sensitivity and specificity than SD Biosensor test kit. Among RT-PCR-positive cases, individuals who had a previous documented SARS-CoV-2 infection, coinfection with another respiratory pathogen or tested ≥ 6 days from symptom onset had higher odds of testing RAT-negative, but the associations were attenuated after adjustment for cycle threshold values (proxy for viral load). There was no significant difference in RAT performance between Omicron sublineages BA.2, BA.5 and XBB.1. Conclusion Diagnostic performance of RAT was not affected by changes in predominant circulating Omicron sublineages. However, reinfection cases may be under ascertained by RAT. In individuals with a previous SARS-CoV-2 infection episode or symptom onset ≥ 6 days prior to testing, a confirmatory RT-PCR may be considered if there is high clinical suspicion.

Prompt diagnosis of coronavirus disease 2019 (COVID-19) is requisite due to the upsurge of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) cases globally. Real-time reverse-transcription polymerase chain reaction (rRT-PCR) remains as the gold standard for the diagnosis of SARS-CoV-2 due to its higher sensitivity and specificity. Regardless, due to its longer turnaround time and expertise, bed side testing rapid antigen based tests were developed in order for portable, rapid diagnosis of the disease. The present study delineates the utility of Rapid Antigen Testing (RAT) screening among symptomatic and asymptomatic patients in a tertiary care hospital. This is a retrospective data collection study from Indian Council of Medical Research (ICMR) portal by exporting the excel sheet from March 2021 to March 2022 who undergone COVID testing in a tertiary care diagnostics facility. The demographic and vaccination details of the individuals were extracted using ICMR Sample referral form (SRF) from all patients who are tested for RAT. Of the total 9898 patients tested for RAT, 392 and 9506 were vaccinated and unvaccinated, respectively. Among them, number of positives was 3% and 15% respectively. The odds ratio showed that the vaccinated individuals had 81.4% reduced risk of getting infection compared to unvaccinated individuals (OR-0.186; p=0.001). A significant difference was observed between the type of vaccine used and COVID infection, majority of them had taken Covishield (83.5%) followed by Covaxin (16%) [p=0.0005]. Males showed a marginally significant p trend with COVID infectivity (OR=1.114, p=0.073) too. RAT is useful as a screening test for rapid diagnosis of infection in patients who are more prone to spread the disease. As RAT is cost effective and had short-turnaround time, it can be recommended in areas with upsurge in SARS-CoV-2 cases to administer isolation and infection control measures.

Background: While numerous studies have evaluated the real-world performance of rapid antigen tests (RATs), data on the effect of Omicron sublineages such as XBB and reinfections on RAT performance is limited. We assessed the performance of RATs and factors associated with RAT-negative results among individuals who tested SARS-CoV-2-positive by reverse transcription-polymerase chain reaction (RT-PCR). Methods: We conducted a retrospective study among Singapore residents who underwent testing for SARS-CoV-2 with RAT (Acon Flowflex or SD Biosensor) and RT-PCR in the same clinical encounter between 9 May 2022 and 21 November 2022. RT-PCR served as a reference standard for RAT performance. Logistic regression was used to estimate the odds ratios (OR) of factors associated with negative RAT results among RT-PCR-positive cases. Results: Of 8,620 clinical encounters analysed, 3,519 (40.8%) were SARS-CoV-2-positive on RT-PCR. Overall sensitivity and specificity of RAT was 84.6% (95% CI 83.3–85.7%) and 99.4% (95% CI 99.1–99.6%) respectively. Acon Flowflex consistently achieved higher sensitivity and specificity than SD Biosensor test kit. Among RT-PCR-positive cases, individuals who had a previous documented SARS-CoV-2 infection, coinfection with another respiratory pathogen or tested ≥ 6 days from symptom onset had higher odds of testing RAT-negative, but the associations were attenuated after adjustment for cycle threshold values (proxy for viral load). There was no significant difference in RAT performance between Omicron sublineages BA.2, BA.5 and XBB.1. Conclusion: Diagnostic performance of RAT was not affected by changes in predominant circulating Omicron sublineages. However, reinfection cases may be under ascertained by RAT. In individuals with a previous SARS-CoV-2 infection episode or symptom onset ≥ 6 days prior to testing, a confirmatory RT-PCR may be considered if there is high clinical suspicion. [ABSTRACT FROM AUTHOR]

Many reverse transcription polymerase chain reaction (RT-PCR) methods exist that can detect SARS-CoV-2 RNA in different matrices. RT-PCR is highly sensitive, although viral RNA may be detected long after active infection has taken place. SARS-CoV-2 proteins have shorter detection windows hence their detection might be more meaningful. Given salivary droplets represent a main source of transmission, we explored the detection of viral RNA and protein using four different detection platforms including SISCAPA peptide immunoaffinity liquid chromatography-mass spectrometry (SISCAPA-LC-MS) using polyclonal capture antibodies. The SISCAPA-LC MS method was compared to RT-PCR, RT-loop-mediated isothermal amplification (RT-LAMP), and a lateral flow rapid antigen test (RAT) for the detection of virus material in the drool saliva of 102 patients hospitalised after infection with SARS-CoV-2. Cycle thresholds (Ct) of RT-PCR (E gene) were compared to RT-LAMP time-to-positive (TTP) (NE and Orf1a genes), RAT optical densitometry measurements (test line/control line ratio) and to SISCAPA-LC-MS for measurements of viral protein. SISCAPA-LC-MS showed low sensitivity (37.7 %) but high specificity (89.8 %). RAT showed lower sensitivity (24.5 %) and high specificity (100 %). RT-LAMP had high sensitivity (83.0 %) and specificity (100.0 %). At high initial viral RNA loads (<20 Ct), results obtained using SISCAPA-LC-MS correlated with RT-PCR (R2 0.57, p-value 0.002). Detection of SARS-CoV-2 nucleoprotein in saliva was less frequent than the detection of viral RNA. The SISCAPA-LC-MS method allowed processing of multiple samples in <150 min and was scalable, enabling high throughput. [ABSTRACT FROM AUTHOR]

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Prompt diagnosis of coronavirus disease 2019 (COVID-19) is requisite due to the upsurge of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) cases globally. Real-time reverse-transcription polymerase chain reaction (rRT-PCR) remains as the gold standard for the diagnosis of SARS-CoV-2 due to its higher sensitivity and specificity. Regardless, due to its longer turnaround time and expertise, bed side testing rapid antigen based tests were developed in order for portable, rapid diagnosis of the disease. The present study delineates the utility of Rapid Antigen Testing (RAT) screening among symptomatic and asymptomatic patients in a tertiary care hospital. This is a retrospective data collection study from Indian Council of Medical Research (ICMR) portal by exporting the excel sheet from March 2021 to March 2022 who undergone COVID testing in a tertiary care diagnostics facility. The demographic and vaccination details of the individuals were extracted using ICMR Sample referral form (SRF) from all patients who are tested for RAT. Of the total 9898 patients tested for RAT, 392 and 9506 were vaccinated and unvaccinated, respectively. Among them, number of positives was 3% and 15% respectively. The odds ratio showed that the vaccinated individuals had 81.4% reduced risk of getting infection compared to unvaccinated individuals (OR-0.186; p=0.001). A significant difference was observed between the type of vaccine used and COVID infection, majority of them had taken Covishield (83.5%) followed by Covaxin (16%) [p=0.0005]. Males showed a marginally significant p trend with COVID infectivity (OR=1.114, p=0.073) too. RAT is useful as a screening test for rapid diagnosis of infection in patients who are more prone to spread the disease. As RAT is cost effective and had short-turnaround time, it can be recommended in areas with upsurge in SARS-CoV-2 cases to administer isolation and infection control measures. [ABSTRACT FROM AUTHOR]

Background: Two rapid antigen tests (RATs) for COVID-19 targeting the nucleocapsid protein of SARS-CoV-2 were compared with real-time RT-PCR as the reference method. Methods: Ninety-six nasopharyngeal swab samples, comprising 56 positive and 40 negative samples confirmed through rRT-PCR were collected and retested to determine the reliability of the two nasopharyngeal RATs. Results: The overall sensitivity and specificity of both RATs were 64.3% (95% confidence interval 50.4 - 76.6%) and 100% (95% confidence interval 91.2 - 100%), respectively. Cohen's kappa coefficient of agreement of both RATs to rRT-PCR was 0.600 (95% confidence interval 0.457 - 0.743) (p < 0.001), showing almost perfect agreement when the Ct values were less than 25 in rRT-PCR. A significant difference in Ct values between true positives and false negatives was observed (Mann-Whitney-Wilcoxon test; p < 0.001). Conclusions: Compared to rRT-PCR, RATs have fewer false negatives. In suspected COVID-19 cases, negative RAT results should be retested using either RAT or rRT-PCR. [ABSTRACT FROM AUTHOR]

Background: There is little data about the performance of multiplex rapid antigen tests (RATs) on the detection of SARS-CoV-2, influenza A (Flu A), and influenza B (Flu B). This study is to evaluate the performance of Panbio COVID-19/Flu A&B rapid panel (Abbott Diagnostics, Korea) and analyze the factors influencing its sensitivity. Methods: Nasopharyngeal swabs were collected and stored at the Korea University Anam hospital. In total, 400 residual samples from nasopharyngeal swabs were examined. The diagnostic accuracy of RAT was compared to that of RT-qPCR using the Allplex SARS-CoV-2/FluA/FluB/RSV Assay (Seegene, Seoul, South Korea). Results: Panbio COVID-19/Flu A&B rapid panel showed the sensitivities of 88.0%, 92.0%, and 100% for SARS-CoV-2, Flu A, and Flu B, respectively, and specificities of 100% for all. The agreements with previously licensed single-plex RATs were shown to be high. In the analysis of variables affecting sensitivity, inappropriate sampling time after symptom onset (STASO) and high cycle threshold (Ct value) were shown to negatively affect the sensitivity. Conclusions: In conclusion, the multiplex RAT is useful for diagnosing SARS-CoV-2 and Flu A/B, but more clinical studies are needed. [ABSTRACT FROM AUTHOR]

Mucormycosis is a highly aggressive angio-invasive disease of humans caused by Mucorales fungi. Prior to the COVID-19 pandemic, mucormycosis was a rare mycosis typically seen in immunocompromised patients with hematological malignancies or in transplant recipients. During the second wave of the pandemic, there was a dramatic increase in the disease, especially in India where a unique set of circumstances led to large numbers of life-threatening and disfiguring rhino-orbital-cerebral mucormycosis (ROCM) infections. The review examines mucormycosis as a super-infection of COVID-19 patients, and the risk factors for COVID-19-associated mucormycosis (CAM) that drove the ROCM epidemic in India. The limitations of current diagnostic procedures are identified, and the measures needed to improve the speed and accuracy of detection discussed. Despite increased awareness, global healthcare systems remain unprepared for further outbreaks of ROCM. Current diagnosis of the disease is slow and inaccurate, negatively impacting on patient survival. This is most evident in low- to middle-income countries which lack suitably equipped diagnostic facilities for rapid identification of the infecting pathogens. Rapid antigen testing using point-of-care lateral-flow assays could potentially have aided in the quick and accurate diagnosis of the disease, allowing earlier intervention with surgery and Mucorales-active antifungal drugs. [ABSTRACT FROM AUTHOR]

SARS-CoV-2 is highly contagious, which spreads even by patients having no clinical symptoms or also from people suffering with only mild symptoms. The gold standard test for its diagnosis is reverse-transcription PCR (RT-PCR) but at times of pandemic, Rapid antigen tests (RAT) are required, which has a very less turn-around time. Evaluation of the performance of COVID-19 Rapid antigen test in comparison to SARS-CoV-2 RT-PCR using nasopharyngeal swab, in relation to RNA dependent RNA polymerase (RdRp) Cycle threshold (Ct) values. This observational and cross-sectional study was done on patients coming with features of Influenza-like illness (ILI) or for any aerosol generating procedure or on high-risk patients seeking hospitalization. Both RT-PCR and RAT for COVID-19 were done on samples collected from each patient and results were compared. Altogether, 5314 samples were tested, out of which 104 (01.95 %) & 229 (04.31 %) samples were found positive by the RAT & RT PCR test, respectively. Sensitivity, specificity, PPV and NPV of RAT were found to be 44.54%, 99.96%, 98.08% and 97.56%, respectively. 98.9 % of samples with Ct value ≤ 20 were positive by RAT, whereas only 2.2% samples having Ct value ≥ 26 were found to be positive. Cases having lower Ct values were found to be more symptomatic and vice-versa. RAT are not efficient in detecting the virus in samples showing high Ct values (Ct ≥ 26) by RT-PCR test. Patients with samples showing low Ct values (Ct ≤ 20) had more severe symptoms and vice-versa.

Rapid antigen testing (RAT) is one of the most powerful tools for SARS-CoV-2 detection. The OnSite COVID-19 Ag Rapid Test is an antigen-based, point-of-care test approved by the WHO for Emergency Use Listing. The Nucleocapsid (N) gene mutations found in the emerging Omicron sublineages lead to the question of RAT performance. To ensure the diagnostic performance of the study RAT during rapidly mutated Omicron variants. We independently evaluated the performance of this assay in 1098 archived samples collected in Thailand during October 2022–February 2023, which were 798 and 300 COVID-19 real-time RT-PCR positive and negative, respectively. The assay performed with 100% sensitivity and 100% specificity using a cycle threshold (Ct) of <20 for the RT-PCR. The sensitivity decreased to 88% when using Ct <30. Most of the SARS-CoV-2 found were Omicron BA.2 (99%), harboring six known N mutations (P13L, E31del, S33del, R203K, G204R and S413R). Eight samples containing hybrid variants (XBB.1*, XBB.2 and XBJ) were detected by the study RAT. This RAT detects all Omicron sublineages known to be circulating in Thailand. These results confirmed the good performance of the study RAT for detecting Omicron variants and its appropriateness for individual diagnosis and for genomic surveillance. [ABSTRACT FROM AUTHOR]

Background and objectives: Timely detection of SARS-CoV-2 infection with subsequent contact tracing and rapid isolation are considered critical to containing the pandemic, which continues with the emergence of new variants. Hence, there is an ongoing need for reliable point-of-care antigen rapid diagnostic tests (Ag-RDT). This report describes the development, evaluation, and analytical sensitivity of the diagnostic performance of the InteliSwab® COVID-19 Rapid Test. Methods: Samples from 165 symptomatic subjects were tested with InteliSwab® and the results were compared to RT-PCR to determine the antigen test performance. The analytical sensitivity of InteliSwab® for the detection of different variants was assessed by limit of detection (LOD) determination using recombinant nucleocapsid proteins (NPs) and testing with virus isolates. Western immunoblot independently confirmed that each monoclonal Ab is capable of binding to all variants tested thus far. Results: The overall positivity rate by RT-PCR was 37% for the 165 symptomatic subjects. Based on RT-PCR results as the reference standard, InteliSwab® showed clinical sensitivity and specificity of 85.2% (95% CI, 74.3–92.0%) and 98.1% (95% CI, 93.3–99.7%), respectively. The overall agreement was 93.3% (Kappa index value 0.85; 95% CI, 0.77–0.74) between RT-PCR and InteliSwab® test results. Furthermore, the evaluation of analytical sensitivity for different SARS-CoV-2 variants by InteliSwab® was comparable in the detection of all the variants tested, including Omicron subvariants, BA.4, BA.5, and BQ.1. Conclusions: Due to the surge of infections caused by different variants from time to time, there is a critical need to evaluate the sensitivity of rapid antigen-detecting tests for new variants. The study findings showed the robust diagnostic performance of InteliSwab® and analytical sensitivity in detecting different SARS-CoV-2 variants, including the Omicron subvariants. With the integrated swab and excellent sensitivity and variant detection, this test has high potential as a point-of-care Ag-RDT in various settings when molecular assays are in limited supply and rapid diagnosis of SARS-CoV-2 is necessary. [ABSTRACT FROM AUTHOR]

Background In autumn 2022, the epidemics due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), respiratory syncytial virus (RSV), and influenza overlapped, and these diseases can present with the same symptomatology. The use of a triple antigen test (SARS-CoV-2 + influenza A/B + RSV) seems crucial for accurate viral diagnosis in the context of implementing long-acting monoclonal antibody vaccination against RSV in the upcoming RSV season. Methods We assessed the usefulness of the triple test in real life in this prospective study performed from October 2022 to May 2023 and involving 116 pediatricians (2 emergency department pediatricians and 114 ambulatory pediatricians). Children <15 years old with flu-like illness (with fever), bronchiolitis (dyspnea ± wheezing), otitis, and croup were enrolled and sampled with a nasal triple test. Results For 8329 children with flu-like illness (65.3%), bronchiolitis (17.9%), otitis (8.8%), and croup (6.3%), the use of the triple test led to a viral diagnosis in 47.9% of cases. The highest RSV positivity occurred in children with bronchiolitis (32.9%). The highest influenza A and B positivity (24.6% and 19.6%) occurred in children with flu-like illness. A succession of 3 epidemics (RSV and influenza A and B) occurred over time with several overlap periods. Conclusions The triple test allowed for a viral diagnosis in half of our cases. The upcoming introduction of RSV prevention will emphasize the need for active surveillance with viral results both in ambulatory settings and hospitals. Clinical Trials Registration. NCT0441231. [ABSTRACT FROM AUTHOR]

SARS-CoV-2 is highly contagious, which spreads even by patients having no clinical symptoms or also from people suffering with only mild symptoms. The gold standard test for its diagnosis is reverse- transcription PCR (RT-PCR) but at times of pandemic, Rapid antigen tests (RAT) are required, which has a very less turn-around time. Evaluation of the performance of COVID-19 Rapid antigen test in comparison to SARS-CoV-2 RT-PCR using nasopharyngeal swab, in relation to RNA dependent RNA polymerase (RdRp) Cycle threshold (Ct) values. This observational and cross-sectional study was done on patients coming with features of Influenza-like illness (ILI) or for any aerosol generating procedure or on high-risk patients seeking hospitalization. Both RT-PCR and RAT for COVID-19 were done on samples collected from each patient and results were compared. Altogether, 5314 samples were tested, out of which 104 (01.95 %) & 229 (04.31 %) samples were found positive by the RAT & RT PCR test, respectively. Sensitivity, specificity, PPV and NPV of RAT were found to be 44.54%, 99.96%, 98.08% and 97.56%, respectively. 98.9 % of samples with Ct value ≤ 20 were positive by RAT, whereas only 2.2% samples having Ct value ≥ 26 were found to be positive. Cases having lower Ct values were found to be more symptomatic and vice-versa. RAT are not efficient in detecting the virus in samples showing high Ct values (Ct ≥ 26) by RT-PCR test. Patients with samples showing low Ct values (Ct ≤ 20) had more severe symptoms and vice-versa. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the diagnostic performance of the rapid antigen test (RAT) for screening patients with cycle threshold (Ct) values of SARS-CoV-2 reverse transcription-polymerase chain reaction (RT-PCR) in the emergency department. Previous studies have shown that Ct values could be used as indicators of infectiousness. Therefore, we considered the Ct value an indicator of potential infectiousness. This single-center retrospective observational study was conducted between January 1, 2020, and March 31, 2022. Patients who underwent both RT-PCR and RAT for the diagnosis of COVID-19 were included. Patients with negative RT-PCR results were excluded. Patients with Ct values lower than 26 and 30 were considered potentially infectious for COVID-19. A total of 386 patients were analyzed. At Ct value cutoffs of 26 and 30, the result of the RAT showed a sensitivity of 82% and 74%, specificity of 84% and 89%, and area under the curve (AUC) of 0.829 and 0.813, respectively, in the receiver operating characteristic curve. However, the NPV was relatively low at 55% and 25%. The RAT might be a rapid screening tool for detecting patients with the infectiousness of SARS-CoV-2. However, considering the low NPV, it is challenging to depend only on a negative test result from an antigen test to terminate quarantine. Clinicians should consider additional factors, such as the duration of symptoms and the immunocompromised state, for SARS-CoV-2 transmission. [ABSTRACT FROM AUTHOR]

Single-target rapid antigen tests (RATs) are commonly used to detect highly transmissible respiratory viruses (RVs), such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza viruses. The simultaneous detection of RVs presenting overlapping symptoms is vital in making appropriate decisions about treatment, isolation, and resource utilization; however, few studies have evaluated multiplex RATs for SARS-CoV-2 and other RVs. We assessed the diagnostic performance of multiplex RATs targeting both the SARS-CoV-2 and influenza A/B viruses with the GenBody Influenza/COVID-19 Ag Triple, InstaView COVID-19/Flu Ag Combo (InstaView), STANDARDTM Q COVID-19 Ag Test, and STANDARDTM Q Influenza A/B Test kits using 974 nasopharyngeal swab samples. The cycle threshold values obtained from the real-time reverse transcription polymerase chain reaction results showed higher sensitivity (72.7–100%) when the values were below, rather than above, the cut-off values. The InstaView kit exhibited significantly higher positivity rates (80.21% for SARS-CoV-2, 61.75% for influenza A, and 46.15% for influenza B) and cut-off values (25.57 for SARS-CoV-2, 21.19 for influenza A, and 22.35 for influenza B) than the other two kits, and was able to detect SARS-CoV-2 Omicron subvariants. Therefore, the InstaView kit is the best choice for routine screening for both SARS-CoV-2 and influenza A/B in local communities. [ABSTRACT FROM AUTHOR]

Introduction: The global COVID-19 pandemic and seasonal influenza outbreaks have drawn attention to the critical need for accurate and efficient diagnostic tools.Methods: The performance of the InstaView COVID-19/Flu Ag Combo Test, which was designed to simultaneously detect the SARS-CoV-2, influenza A, and influenza B viruses, was analytically and clinically evaluated.Results: The InstaView COVID-19/Flu Ag Combo Test exhibited robust detection capabilities, accurately identifying SARS-CoV-2, influenza A, and influenza B viruses over a wide concentration range (1.41 × 103 to 7.05 × 104 TCID50/mL). Extensive testing against potential cross-reactants and interferences yielded no false-positive results, indicating the high specificity of the test. Clinical evaluation further confirmed the kit’s reliability, with sensitivity ranging from 95.1% to 98.2% for SARS-CoV-2, 88.9%–95.2% for influenza A, and 91.7%–100% for influenza B depending on the sample type. The specificity was consistently 100% for all of the targeted viruses.Discussion: The InstaView COVID-19/Flu Ag Combo Test thus demonstrated high performance, ease of use, rapid results, and the ability to precisely detect SARS-CoV-2 and influenza A/B infections, making it an effective tool in streamlining diagnostic workflows, optimizing resource allocation, and improving patient outcomes.

Abstract Background Rapid and accurate diagnosis of individuals with SARS-CoV-2 infection is an effective way to prevent and control the spread of COVID-19. Although the detection of SARS‐CoV‐2 viral RNA by RT‐qPCR is the gold standard for COVID-19 testing, the use of antigen-detecting rapid diagnostic tests (Ag-RDTs) is emerging as a complementary surveillance tool as Omicron case numbers skyrocket worldwide. However, the results from Ag-RDTs are less accurate in individuals with low viral loads. Results To develop a highly sensitive and accurate Ag-RDT, 90 monoclonal antibodies were raised from guinea pigs immunized with SARS CoV-2 nucleocapsid protein (CoV-2-NP). By applying a capture antibody recognizing the structural epitope of the N-terminal domain of CoV-2-NP and a detection antibody recognizing the C-terminal tail of CoV-2-NP to an automated chemiluminescence flow-through membrane immunoassay device, we developed a novel Ag-RDT, CoV-2-POCube. The CoV-2-POCube exclusively recognizes CoV-2-NP variants but not the nucleocapsid proteins of other human coronaviruses. The CoV-2-POCube achieved a limit of detection sensitivity of 0.20 ~ 0.66 pg/mL of CoV-2-NPs, demonstrating more than 100 times greater sensitivity than commercially available SARS-CoV-2 Ag-RDTs. Conclusions CoV-2-POCube has high analytical sensitivity and can detect SARS-CoV-2 variants in 15 min without observing the high-dose hook effect, thus meeting the need for early SARS-CoV-2 diagnosis with lower viral load. CoV-2-POCube is a promising alternative to currently available diagnostic devices for faster clinical decision making in individuals with suspected COVID-19 in resource-limited settings.

Background: Community infections of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have increased rapidly since the emergence of the Omicron strain. During the eighth and ninth pandemic waves—when movement restrictions in the community were eased—the all-case registration system was changed, and the actual status of infection became uncertain. Methods: We conducted regular rapid antigen tests (R-RATs) once or twice a week as self-testing to examine the actual state of coronavirus disease (COVID-19) diagnosis among healthcare employees. Results: Overall, 320 (1.42/day) and 299 (1.76/day) employees were infected in the eighth and ninth pandemic waves. During both periods, 59/263 doctors (22.4%), 335/806 nurses (41.6%), 92/194 administrative employees (47.4%), and 129/218 clinical laboratory technicians (59.2%) were infected. In the eighth wave, 56 of 195 employees were infected through close contact; in the ninth wave, 26 of 62 employees were infected. No significant difference was observed in the number of vaccinations between infected and non-infected employees. The positivity rate of R-RATs was 0.41% and 0.45% in the eighth and ninth waves. R-RATs detected infection in 212 and 229 employees during the eighth and ninth waves, respectively; the ratio of R-RAT-detected positive employees to those who reported infection was significantly higher during the ninth wave (odds ratio: 1.67, 95% confidence interval: 1.17–2.37, p < 0.001). Conclusions: The number of infected healthcare employees remained high during the eighth and ninth pandemic waves in Japan. The R-RAT is considered effective for detecting mild or asymptomatic COVID-19 at an early stage and at a high rate in healthcare employees.

Abstract Background Rapid antigen-detection tests (Ag-RDTs) are used to diagnose SARS-CoV-2 infection. Real-world studies of Ag-RDTs are necessary to evaluate their diagnostic yield in paediatric patients. Our aim was to evaluate the accuracy of the Panbio™ Rapid Antigen Test for SARS-CoV-2 in the setting of a primary health care centre (PHC), with use of the Reverse Transcription-Polymerase Chain Reaction (RT-PCR) as gold standard. Methods This prospective diagnostic study was conducted at PHCs in Mallorca, Spain. Patients were ≤ 18 years-old that attended sites for RT-PCR testing due to symptoms suggestive of infection (fever, headache, nasal congestion and dry cough, among others) or epidemiological exposure (close contacts). Two samples were collected: a nasal mid-turbinate sample for Ag-RDTs and a nasopharyngeal swab for RT-PCR testing. The sensitivity, specificity, and predictive values of the AgRDT were calculated using the RT-PCR results as the reference. Results We examined 1142 participants from 0 to 18 years (47.5% female, mean age 8.9 ± 4.8 years, median 9.0 [5.0–13.0]). There were 84 positive RT-PCR results (pre-test probability of 7.3%) and 52 positive Ag-RDT results. The sensitivity of the Ag-RDT was 59.5% (95% Confidence Interval (CI): 48.2–69.9%), the specificity was 99.8% (95%CI: 99.2–99.9%), the positive predictive value was 96.1% (95%CI: 85.6–99.4%), and the negative predictive value was 96.8% (95%CI: 95.6–97.7%). The sensitivity for individuals referred by a general practitioner (GP) or paediatrician due to symptoms was 71.4% (95%CI: 51.5–86.0%) and for asymptomatic individuals was 50.0% (95%CI: 9.1–90.8%). The specificity was greater than 98.9% overall and in all subgroups. The sensitivity was 73.0% (95%CI: 52.0–87.5%) for referred patients due to symptoms and who were tested within 5 days since symptom onset. No significant statistical differences between any groups were found. There were 34 false-negative Ag-RDT results (40.5%) and 2 false-positive Ag-RDT results (0.2%). Conclusion The sensitivity of the Panbio™ Test in paediatric individuals is below the minimum of 80% recommended by the World Health Organization for Ag-RDTs. This test had better accuracy in individuals referred by a GP or paediatrician due to symptoms, rather than those who were asymptomatic or referred due to epidemiological exposure. The RT-PCR test using a nasopharyngeal swab is accurate, but a less invasive alternative that has better sensitivity than the Panbio™ Test is needed for paediatric populations.

ABSTRACTCurrent guidelines recommend that individuals with moderate COVID-19 disease isolate for 5 days after the first appearance of symptoms or a positive SARS-CoV-2 test. It would be useful to understand the time course of infectious virus production and its correlation with virus detection using a rapid antigen test (RAT) or quantitative reverse transcriptase (qRT)-PCR. In a phase 2 study, 242 vaccinated patients with COVID-19 and at low risk for progression to severe disease initiated 5 days of treatment with pomotrelvir (PBI-0451, a SARS-CoV-2 main protease inhibitor) or placebo within 5 days after symptom onset. The primary endpoint, the proportion of subjects with SARS-CoV-2 viral titers below the limit of detection on Day 3 of treatment in the pomotrelvir versus placebo groups, was not met. No between-group differences in SARS-CoV-2 clearance or symptom resolution or alleviation were observed. Additional analyses evaluated the dynamics of SARS-CoV-2 replication in mid-turbinate nasal swabs and saliva samples using infectious virus assay (IVA), RAT, and qRT-PCR. SARS-CoV-2 cleared rapidly, with negative results first determined by IVA (TCID50 below the limit of detection), followed by the RAT (negative for SARS-CoV-2 N antigen), and qRT-PCR (RNA below the limit of detection), which suggests that delayed initiation of treatment (up to 5 days after symptom onset) may have contributed to the lack of treatment response. Symptom resolution lagged behind viral clearance assessed by IVA and RAT. These data support reliance on a negative RAT to determine when an individual is no longer producing infectious virus and may end isolation.IMPORTANCEA phase 2 double-blind, placebo-controlled study was performed evaluating pomotrelvir, a SARS-CoV-2 Mpro inhibitor, compared with placebo in 242 non-hospitalized, vaccinated, symptomatic adults with COVID-19 (Omicron). No improvement in the decrease of viral replication or relief of symptoms was observed between the two groups when treatment was initiated ≥3 days after symptom onset. These results suggest that future COVID-19 antiviral studies using a similar patient population may need to initiate treatment earlier, like influenza studies. This is the first study to prospectively evaluate SARS-CoV-2 viral dynamics and the time to viral clearance in a significant number of patients using concurrently obtained results from an infectious virus assay, a rapid antigen test (RAT), and a qRT-PCR assay over a 15-day time course. These results suggest that a negative RAT assay is a good indicator of loss of infectious virus and the ability to return to normal activities.

Rapid antigen tests for the detection of SARS-CoV-2 are commonly used for the diagnosis of Covid-19. Previously published data showed a wide range of sensitivity and specificity of RATs, but these studies were performed on relatively small numbers of samples and using only limited numbers of virus variants. The aim of the study was to evaluate the main parameters of a commonly used RAT for 4 different virus variants in comparison with PCR. Material and methods: A set of 2874 samples obtained from Covid-19 patients were examined both by PCR and RAT. Two commercial PCR kits (Generi Biotech, Diana Biotechnologies) and one RAT – Abbott Panbio™ COVID 19 Ag Rapid – were compared for their sensitivity and specificity in samples positive for one of the four different SARS-CoV-2 variants – B.1.258 (n = 496), Alpha (n = 645), Delta/Delta+ (n = 687), and Omicron (n = 1046). Results: The sensitivity of Panbio™ COVID19 Ag Rapid test varied from 80.0 % in Omicron to 88.92 % in Alpha variants. The specificities of the RAT for all variants reached above 93 %. Statistically significant differences were found between the results from RAT assay in select virus variants. In addition, significantly higher sensitivity (p

Background: Rapid screening for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was important in the emergency department during the coronavirus disease 2019 (COVID-19) pandemic. Real-time polymerase chain reaction (RT-PCR) is the standard method for detecting SARS-CoV-2, but it requires several hours to provide results. Instead, the rapid antigen test (RAT) has a short turnaround time and can be used at the bedside but shows low sensitivity. To overcome these shortcomings, the clinical utility of stepwise testing of RAT with RTPCR in the emergency department was analyzed. Methods: Patients who underwent SARS-CoV-2 RAT (SD Biosensor or Abbott) and RT-PCR (Seegene Allplex or GeneXpert) testing simultaneously at the emergency department in South Korea from January 2021 to March 2022 were enrolled. We compared the performance status of RAT with that of RT-PCR and evaluated the clinical utility of RAT as a screening tool for patients visiting the emergency department. Results: A total of 7,574 patients were included. The overall prevalence of COVID-19 was 1.9% (146/7,574). The sensitivity and specificity of the RAT were 69.2% and 99.9%, respectively, and the positive and negative predictive values were 96.2% and 99.4%, respectively. Based on the cycle threshold (Ct) of the E gene, the sensitivity was 86.0% in patients with Ct < 26, but the sensitivity was 9.3% in patients with Ct ≥ 26. Conclusions: In the COVID-19 pandemic, RAT can be used as supplement test for the screening strategy using RT-PCR in the emergency department because it is rapid, highly specific, and relatively sensitive in patients with high viral load. [ABSTRACT FROM AUTHOR]

BACKGROUND: Per Centers for Disease Control and Prevention guidance, students with COVID‐19 may end isolation after 5 days if symptoms are improving; some individuals may still be contagious. Rapid antigen testing identifies possibly infectious virus. We report on a test‐to‐return (TTR) program in a Massachusetts school district to inform policy decisions about return to school after COVID‐19. METHODS: During the 2021‐2022 Omicron BA.1 surge, students with COVID‐19 could return on day 6‐10 if they met symptom criteria and had a negative rapid test; students with positive rapid tests and those who declined TTR remained isolated until day 11. TTR positivity rates were compared by grade level, vaccination status, symptom status, and day of infection. RESULTS: 31.4% of students had a positive TTR rapid test; there were no differences by grade or vaccination status. Ever‐symptomatic students were more likely to have a positive rapid test (75/174 [43.1%] vs 18/104 [17.3%]). For ever‐symptomatic students, TTR positivity decreased by day of infection. CONCLUSIONS: A substantial proportion of students may still be contagious 6 days after onset of COVID‐19 infection. TTR programs may increase or reduce missed school days, depending on when return is otherwise allowed (day 6 or 11). The impact of TTR programs on school‐associated transmission remains unknown. [ABSTRACT FROM AUTHOR]

Although rapid antigen tests (RADTs) for group A streptococcus (GAS) can help diagnose group A streptococcal pharyngitis, little is known about the inappropriate use of these RADTs. This retrospective observational study compared the appropriate vs. inappropriate use of RADTs in patients who had a RADT between January 2019 and August 2022. RADTs for patients with a low Centor score of 0–1 point were deemed inappropriate. Of the 1015 patients, 380 (37.4%) had inappropriate RADTs. Patients with asthma were associated with an increased risk of inappropriate testing. In contrast, during the coronavirus 2019 pandemic, outpatients and residents were associated with a reduced risk of inappropriate testing. Consequent to the inappropriate use of RADTs, 162 (16.0%) patients received potentially inappropriate antibiotics. Our results suggest that diagnostic stewardship for pharyngitis, including education for healthcare workers, is needed to reduce inappropriate test ordering and prevent unnecessary care. [ABSTRACT FROM AUTHOR]

Background: Rapid and accurate diagnosis of individuals with SARS-CoV-2 infection is an effective way to prevent and control the spread of COVID-19. Although the detection of SARS‐CoV‐2 viral RNA by RT‐qPCR is the gold standard for COVID-19 testing, the use of antigen-detecting rapid diagnostic tests (Ag-RDTs) is emerging as a complementary surveillance tool as Omicron case numbers skyrocket worldwide. However, the results from Ag-RDTs are less accurate in individuals with low viral loads. Results: To develop a highly sensitive and accurate Ag-RDT, 90 monoclonal antibodies were raised from guinea pigs immunized with SARS CoV-2 nucleocapsid protein (CoV-2-NP). By applying a capture antibody recognizing the structural epitope of the N-terminal domain of CoV-2-NP and a detection antibody recognizing the C-terminal tail of CoV-2-NP to an automated chemiluminescence flow-through membrane immunoassay device, we developed a novel Ag-RDT, CoV-2-POCube. The CoV-2-POCube exclusively recognizes CoV-2-NP variants but not the nucleocapsid proteins of other human coronaviruses. The CoV-2-POCube achieved a limit of detection sensitivity of 0.20 ~ 0.66 pg/mL of CoV-2-NPs, demonstrating more than 100 times greater sensitivity than commercially available SARS-CoV-2 Ag-RDTs. Conclusions: CoV-2-POCube has high analytical sensitivity and can detect SARS-CoV-2 variants in 15 min without observing the high-dose hook effect, thus meeting the need for early SARS-CoV-2 diagnosis with lower viral load. CoV-2-POCube is a promising alternative to currently available diagnostic devices for faster clinical decision making in individuals with suspected COVID-19 in resource-limited settings. [ABSTRACT FROM AUTHOR]

The SARS-CoV-2 pandemic has impacted millions of lives worldwide. Molecular assays and serological tests have been approved under EUA (emergency use authorization) by the FDA (food and drug administration), given these unprecedented times. These tests are not only critical for confirming the clinical diagnosis and making therapeutic decisions but also play an important role in the understanding of the epidemiology of the pandemic. There is limited experience with currently available tests and differences may exist among tests even using similar technology. The focus of this review is to improve clinicians understanding of SARS-CoV-2 test procedures including their limitations. We discuss the impact of different host and environmental factors on test results.

We evaluated the performance of the Abbott BinaxNOW rapid antigen test for coronavirus disease 2019 (Binax-CoV2) to detect virus among persons, regardless of symptoms, at a public plaza site of ongoing community transmission. Titration with cultured severe acute respiratory syndrome coronavirus 2 yielded a human observable threshold between 1.6 × 104-4.3 × 104 viral RNA copies (cycle threshold [Ct], 30.3-28.8). Among 878 subjects tested, 3% (26 of 878) were positive by reverse-transcription polymerase chain reaction, of whom 15 of 26 had a Ct

Background: Polymerase chain reaction (PCR) is the benchmark in diagnosing of corona virus disease. It takes at least 4 hours. Multiple studies reported that rapid antigen test could be used. Their role in diagnosing corona virus disease 2019 (COVID-19) is questionable. This study was conducted to assess the accuracy of rapid antigen test in Urology and Nephrology Center Mansoura University, Egypt. Methods: COVID-19 rapid ag test was evaluated in comparison to real time PCR as a gold standard in diagnosis of COVID-19 infection in employees and patients with respiratory symptoms in specialized care facility Urology and Nephrology Center of Mansoura University from March2020 till August 2021. Complete blood picture and non-contrast computerized tomography (CT) was done. Results: Eight hundred and eighty-four (884) individuals (median age 36 years) were included in this study: 478 healthcare workers, 217 non-healthcare workers, and 189 patients. PCR was positive in 569 samples and negative in 315. Out of 315 negative PCR samples, 8 were positive by rapid antigen test with a specificity of 97.4%. Conclusion: Rapid antigen tests in comparison to PCR test have a good accuracy in diagnosis in of COVID-19 infection and can be used during pandemics in low-resource areas.

Abstract Background A highly accurate, rapid, and low-cost COVID-19 test is essential for guiding isolation measures. To date, the most widely used tests are either nucleic acid amplification tests or antigen tests. The objective of this study is to further assess the diagnostic performance of the Binax-CoV2 rapid antigen test in comparison to the current gold standard reverse transcription quantitative polymerase chain reaction (RT-qPCR), with additional analysis of symptomatology and cycle threshold utility. Methods This is a prospective cohort study performed between November and December 2020. Individuals who presented to COVID-19 testing events and received both RT-qPCR and a rapid antigent test were included. Testing occurred at the emergency department of an urban hospital and at a community mobile unit. No fees or appointments were required. Individuals self-reported the presence or absence of symptoms and history of positive COVID-19 test within the previous two weeks. Trained staff collected two subsequent nasopharyngeal swabs of both nares. One set of swabs underwent RT-qPCR and the other underwent Binax-CoV2 assay per manufacturer guidelines. Results A total of 390 patients were included, of which 302 were from the community site. Of these 302, 42 (14%) were RT-qPCR positive. Of the 42 RT-qPCR positive, 30 (71.4%) were also positive by Binax-CoV2. The Binax-CoV2 test had a sensitivity of 71.4% (95% CI: 55%–84%) and a specificity of 99.6% (95% CI: 98%–100%) in this population. Performance of the Binax-CoV2 test performed better in individuals with higher viral load. For symptomatic patients with cycle threshold

Objectives: The SARS-CoV-2 Omicron variant pandemic struck Taiwan in April 2022. Rapid antigen tests (RATs) play an important role in providing rapid results during a pandemic. However, self-collected samples by the children's caregivers without the supervision of medical personnel raise some concerns. Methods: This study was performed to investigate household transmission, clinical characteristics, and antigen performance in a special COVID-19 family clinic in a children's hospital. The performance of at-home RATs was evaluated based on reverse transcription-polymerase chain reaction. Results: We included 627 patients in our study between May 11 and June 10, 2022. The COVID-19 full vaccination rate was significantly higher in adults (98.5%) than in children (5.9%, P

Testing for infection with SARS-CoV-2 is an important intervention in reducing onwards transmission of COVID-19, particularly when combined with the isolation and contact-tracing of positive cases. Many countries with the capacity to do so have made use of lab-processed Polymerase Chain Reaction (PCR) testing targeted at individuals with symptoms and the contacts of confirmed cases. Alternatively, Lateral Flow Tests (LFTs) are able to deliver a result quickly, without lab-processing and at a relatively low cost. Their adoption can support regular mass asymptomatic testing, allowing earlier detection of infection and isolation of infectious individuals. In this paper we extend and apply the agent-based epidemic modelling framework Covasim to explore the impact of regular asymptomatic testing on the peak and total number of infections in an emerging COVID-19 wave. We explore testing with LFTs at different frequency levels within a population with high levels of immunity and with background symptomatic PCR testing, case isolation and contact tracing for testing. The effectiveness of regular asymptomatic testing was compared with ‘lockdown’ interventions seeking to reduce the number of non-household contacts across the whole population through measures such as mandating working from home and restrictions on gatherings. Since regular asymptomatic testing requires only those with a positive result to reduce contact, while lockdown measures require the whole population to reduce contact, any policy decision that seeks to trade off harms from infection against other harms will not automatically favour one over the other. Our results demonstrate that, where such a trade off is being made, at moderate rates of early exponential growth regular asymptomatic testing has the potential to achieve significant infection control without the wider harms associated with additional lockdown measures.

Background: Rapid antigen-detection tests (Ag-RDTs) are used to diagnose SARS-CoV-2 infection. Real-world studies of Ag-RDTs are necessary to evaluate their diagnostic yield in paediatric patients. Our aim was to evaluate the accuracy of the Panbio™ Rapid Antigen Test for SARS-CoV-2 in the setting of a primary health care centre (PHC), with use of the Reverse Transcription-Polymerase Chain Reaction (RT-PCR) as gold standard. Methods: This prospective diagnostic study was conducted at PHCs in Mallorca, Spain. Patients were ≤ 18 years-old that attended sites for RT-PCR testing due to symptoms suggestive of infection (fever, headache, nasal congestion and dry cough, among others) or epidemiological exposure (close contacts). Two samples were collected: a nasal mid-turbinate sample for Ag-RDTs and a nasopharyngeal swab for RT-PCR testing. The sensitivity, specificity, and predictive values of the AgRDT were calculated using the RT-PCR results as the reference. Results: We examined 1142 participants from 0 to 18 years (47.5% female, mean age 8.9 ± 4.8 years, median 9.0 [5.0–13.0]). There were 84 positive RT-PCR results (pre-test probability of 7.3%) and 52 positive Ag-RDT results. The sensitivity of the Ag-RDT was 59.5% (95% Confidence Interval (CI): 48.2–69.9%), the specificity was 99.8% (95%CI: 99.2–99.9%), the positive predictive value was 96.1% (95%CI: 85.6–99.4%), and the negative predictive value was 96.8% (95%CI: 95.6–97.7%). The sensitivity for individuals referred by a general practitioner (GP) or paediatrician due to symptoms was 71.4% (95%CI: 51.5–86.0%) and for asymptomatic individuals was 50.0% (95%CI: 9.1–90.8%). The specificity was greater than 98.9% overall and in all subgroups. The sensitivity was 73.0% (95%CI: 52.0–87.5%) for referred patients due to symptoms and who were tested within 5 days since symptom onset. No significant statistical differences between any groups were found. There were 34 false-negative Ag-RDT results (40.5%) and 2 false-positive Ag-RDT results (0.2%). Conclusion: The sensitivity of the Panbio™ Test in paediatric individuals is below the minimum of 80% recommended by the World Health Organization for Ag-RDTs. This test had better accuracy in individuals referred by a GP or paediatrician due to symptoms, rather than those who were asymptomatic or referred due to epidemiological exposure. The RT-PCR test using a nasopharyngeal swab is accurate, but a less invasive alternative that has better sensitivity than the Panbio™ Test is needed for paediatric populations. [ABSTRACT FROM AUTHOR]

The promising diagnostic performance of rapid antigen tests (RATs) using non-invasive anterior nasal (AN) swab specimens to diagnose COVID-19 has been reported. A large number of RATs are commercially available; however, the careful assessment of RATs is essential prior to their implementation in clinical practice. We evaluated the clinical performance of the GLINE-2019-nCoV Ag Kit as a RAT using AN swabs in a prospective, blinded study. Adult patients who visited outpatient departments and received SARS-CoV-2 tests between August 16 and September 8, 2022, were eligible for this study. Patients who were aged under 18 years and patients without appropriate specimens were excluded. Two sets of AN and nasopharyngeal (NP) swabs were collected from all patients. Each set of specimens was tested by the RAT and quantitative reverse-transcription polymerase chain reaction (RT-qPCR). Of the 138 recruited patients, 84 were positive and 54 were negative by RT-qPCR using NP swabs. The positive agreement rate between RT-qPCR using NP swabs and RAT using AN swabs was 78.6% (95% confidence interval [CI], 68.3%–86.8%), the negative agreement rate was 98.1% (95% CI, 90.1%–99.9%), and the overall agreement rate was 86.2% (95% CI, 79.3%–91.5%), with a κ coefficient of 0.73. The positive agreement rate in the early phase (≤3 days from symptom onset) was >80%, but this fell to 50% in the late phase (≥4 days). This study demonstrates that the GLINE-2019-nCoV Ag Kit using AN swabs has good clinical performance and might be a reliable alternative method for diagnosing COVID-19. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the perception of SARS-CoV-2 detection methods, information sources, and opinions on appropriate behavior after receiving negative or positive test results. Methods: In a questionnaire-based, cross-sectional study conducted between September 1 and November 17, 2021, epidemiological, behavioral, and COVID-19-related data were acquired from the public in Munich, Germany. Results: Most of the 1388 participants obtained information from online media (82.8%) as well as state and federal authorities (80.3%). 93.4% believed in the accuracy of SARS-CoV-2 PCR testing and 41.2% in the accuracy of rapid antigen tests (RATs). However, RATs were preferred for testing (59.1%) over PCR (51.1%). 24.0% of all individuals were willing to ignore hygiene measures and 76.9% were less afraid of SARS-CoV-2 transmission after receiving a negative PCR test (5.9% and 48.8% in case of a negative RAT). 28.8% reported not to self-isolate after receiving a positive RAT. Multivariate analyses revealed that non-vaccinated individuals relied less on information from governmental authorities (p = 0.0004) and more on social media (p = 0.0216), disbelieved in the accuracy of the PCR test (p ≤ 0.0001) while displaying strong preference towards using RATs (p ≤ 0.0001), were more willing to abandon pandemic-related hygiene measures (p ≤ 0.0001), less afraid of transmitting SARS-CoV-2 after a negative RAT (p ≤ 0.0001), and less likely to isolate after a positive RAT (p ≤ 0.0001). Conclusion: Insights into preferred information sources as well as perception, preferences, and behavior related to SARS-CoV-2 testing and hygiene measures are key to refining public health information and surveillance campaigns. Non-vaccinated individuals' divergent believes and behaviors possibly increase their COVID-19 risk. [ABSTRACT FROM AUTHOR]

Nucleic acid amplification tests (NAATs), including polymerase chain reaction (PCR) assays, are more sensitive for the detection of SARS-CoV-2 than rapid antigen tests (RATS), and are the gold standard for diagnosis of acute COVID-19. However NAATs can remain positive for weeks following infection due to low-level shedding of non-viable viral fragments. RATs (in particular self-testing) are the mainstay of COVID-19 diagnosis due to their convenience, speed and high specificity. The sensitivity of RATs is highest within seven days of symptom onset. A negative RAT result may warrant a NAAT or repeat RAT for confirmation. The presence of spike antibodies is consistent with either vaccination or infection. Nucleocapsid antibodies suggest a previous infection. Serological tests measuring neutralising antibodies that infer immunity are not readily available. [ABSTRACT FROM AUTHOR]

Background: The impacts of non-pharmaceutical interventions (NPIs) and vaccine boosters on the transmission of the largest outbreak of COVID-19 (the fifth wave) in Hong Kong have not been reported. The outbreak, dominated by the Omicron BA.2 subvariant, began to spread substantially after the Spring Festival in February, 2022, when the temperature varied greatly (e.g. a cold surge event). Tightening social distancing measures did not succeed in containing the outbreak until later with the use of rapid antigen tests (RAT) and increased vaccination rates. Temperature has been previously found to have significant impact on the transmissibility. Understanding how the public health interventions influence the number of infections in this outbreak provide important insights on prevention and control of COVID-19 during different seasons. Methods: We developed a transmission model incorporating stratified immunity with vaccine-induced antibody responses and the daily changes in population mobility, vaccination and weather factors (i.e. temperature and relative humidity). We fitted the model to the daily reported cases detected by either PCR or RAT between 1 February and 31 March using Bayesian statistics, and quantified the effects of individual NPIs, vaccination and weather factors on transmission dynamics. Results: Model predicted that, with the vaccine uptake, social distancing reduced the cumulative incidence (CI) from 58.2% to 44.5% on average. The use of RAT further reduced the CI to 39.0%. Without vaccine boosters in these two months, the CI increased to 49.1%. While public health interventions are important in reducing the total infections, the outbreak was temporarily driven by the cold surge. If the coldest two days (8.5 °C and 8.8 °C) in February were replaced by the average temperature in that month (15.2 °C), the CI would reduce from 39.0% to 28.2%. Conclusion: Preventing and preparing for the transmission of COVID-19 considering the change in temperature appears to be a cost-effective preventive strategy to lead people to return to normal life.

Background and aims: Accurate and timely diagnosis is crucial for coronavirus disease 2019 (COVID-19) outbreaks. Antigen-detecting rapid diagnostic tests (Ag-RDTs) are easily accessible and affordable, producing rapid results. They are an alternative to the limited gold-standard real-time reverse-transcription polymerase chain reaction (rRT-PCR) tests. This study assessed the performance of Ag-RDTs for COVID-19 outbreaks in institutional settings with high disease prevalence in Kelantan State, Malaysia. Methods: This study analyzed a total of 303 individuals from five institutional outbreaks with paired nasopharyngeal specimens tested for COVID-19 by Ag-RDTs and rRT-PCR. The diagnostic performance of Ag-RDTs was evaluated through rRT-PCR as the gold standard based on cycle threshold (Ct) value, disease prevalence, and manufacturers. Results: There was a moderate agreement between Ag-RDTs and RT-PCR (κ = 0.603; 95% CI: 0.520- 0.686; P < 0.001). The overall specificity was 97.9% (95% CI: 94.1%-99.6%), sensitivity was 63.3% (95% CI: 55.3%-70.8%), accuracy Ag-RDTs was 81.2% (95% CI: 76.4%-85.5%), while positive and negative predictive value was 96.6% (95% CI: 90.2%-98.9%) and 74.1% (95% CI: 70.0%-77.9%), respectively. Further, lower median Ct was reported in 100 (33.0%) true-positive cases compared to 58 (19.1%) false-negative cases (20.3 vs 31.4, P < 0.001). The sensitivity was higher (P < 0.001) in those with high viral load (Ct value ≤ 25.0) with better performance and a prevalence > 10%. In addition, no significant difference was observed between the studied manufacturers. Conclusion: The Ag-RDTs performed well in diagnosing COVID-19 among outbreaks with higher viral load and disease prevalence. High-risk cases tested negative by Ag-RDTs may have low viral load and require confirmation by rRT-PCR.

Abstract Background Diagnostic testing has been pivotal in detecting SARS-CoV-2 infections and reducing transmission through the isolation of positive cases. We quantified the value of implementing frequent, rapid antigen (RA) testing in the workplace to identify screening programs that are cost-effective. Methods To project the number of cases, hospitalizations, and deaths under alternative screening programs, we adapted an agent-based model of COVID-19 transmission and parameterized it with the demographics of Ontario, Canada, incorporating vaccination and waning of immunity. Taking into account healthcare costs and productivity losses associated with each program, we calculated the incremental cost-effectiveness ratio (ICER) with quality-adjusted life year (QALY) as the measure of effect. Considering RT-PCR testing of only severe cases as the baseline scenario, we estimated the incremental net monetary benefits (iNMB) of the screening programs with varying durations and initiation times, as well as different booster coverages of working adults. Results Assuming a willingness-to-pay threshold of CDN$30,000 per QALY loss averted, twice weekly workplace screening was cost-effective only if the program started early during a surge. In most scenarios, the iNMB of RA screening without a confirmatory RT-PCR or RA test was comparable or higher than the iNMB for programs with a confirmatory test for RA-positive cases. When the program started early with a duration of at least 16 weeks and no confirmatory testing, the iNMB exceeded CDN$1.1 million per 100,000 population. Increasing booster coverage of working adults improved the iNMB of RA screening. Conclusions Our findings indicate that frequent RA testing starting very early in a surge, without a confirmatory test, is a preferred screening program for the detection of asymptomatic infections in workplaces.

Background: COVID-19 pandemic continues to be a public health threat. Rapid antigen tests (RATs) for the detection of SARS-CoV-2 infection will help in formulation of clinical and public health strategies for the control of transmission. In India, 49% of COVID-19 tests done are RATs.1 The sensitivity of RAT is 50.6–84%. RAT has specificity ranging from 99.3% to 100%.2 The present study aims at evaluating the RAT screening test done on people attending fever clinic of Shimoga Institute of Medical Sciences, Shivamogga. Aims and Objectives: The objectives of the study were to evaluate the COVID-19 RAT screening test with reverse transcriptase-polymerase chain reaction (RT-PCR) as the gold standard test done at fever clinic of SIMS, Shimoga. Materials and Methods: An observational, cross-sectional analytical study was conducted for a period of 1 month, May 2021. The study participants included all the people attending fever clinic of SIMS, Shimoga. Assuming the sensitivity of RAT to be 85%, power of 80%, and precision of 5%, the calculated sample size was 204. Considering non-response rate of 10%, the final sample size was 224. Secondary data regarding contact number of the people attending fever clinic were collected from the COVID-19 test register. Oral consent was taken after explaining about study and assuring confidentiality. Telephonic interview was done to collect relevant information. Analysis was done using Epi Info software version 7.2.4.0. Descriptive statistics such as percentages and analytical statistics such as Student’s t-test and Chi-square test were used. Results: Overall positivity rate was 43.7%. About 71% of people had contact history. Sensitivity and specificity of RAT test were found to be 64.2% and 97.2%, respectively, and were comparable with the previous studies. Significant difference was found (P