Comparative sensitivity evaluation for 122 CE-marked SARS-CoV-2 antigen rapid tests

ObjectiveThe objective of this study was to evaluate the performance of seven antigen rapid diagnostic tests (Ag RDTs) in a clinical setting to identify those that could be recommended for use in the diagnosis of SARS-CoV-2 infection in Uganda.MethodsThis was a cross-sectional prospective study. Nasopharyngeal swabs were collected consecutively from COVID-19 PCR positive and COVID-19 PCR negative participants at isolation centers and points of entry, and tested with the SARS-CoV-2 Ag RDTs. Test sensitivity and specificity were generated by comparing results against qRT-PCR results (Berlin Protocol) at a cycle threshold (Ct) cut-off of ≤39. Sensitivity was also calculated at Ct cut-offs ≤29 and ≤33.ResultsNone of the Ag RDTs had a sensitivity of ≥80% at Ct cut-off values ≤33 and ≤39. Two kits, Panbio™ COVID-19 Ag and VivaDiag™ SARS-CoV-2 Ag had a sensitivity of ≥80% at a Ct cut-off value of ≤29. Four kits: BIOCREDIT COVID -19 Ag, COVID-19 Ag Respi-Strip, MEDsan® SARS-CoV-2 Antigen Rapid Test and Panbio™ COVID-19 Ag Rapid Test had a specificity of ≥97%.ConclusionsThis evaluation identified one Ag RDT, Panbio™ COVID-19 Ag with a performance at high viral load (Ct value ≤29) reaching that recommended by WHO. This kit was recommended for screening of patients with COVID -19-like symptoms presenting at health facilities.

ABSTRACTCommunity testing is a crucial tool for the early identification of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and transmission control. The emergence of the highly mutated Omicron variant (B.1.1.529) raised concerns about its primary site of replication, impacting sample collection and its detectability by rapid antigen tests. We tested the performance of the Panbio antigen rapid diagnostic test (Ag-RDT) using nasal and oral specimens for COVID-19 diagnosis in 192 symptomatic individuals, with quantitative reverse transcription-PCR (RT-qPCR) of nasopharyngeal samples as a control. Variant of concern (VOC) investigation was performed with the 4Plex SARS-CoV-2 screening kit. The SARS-CoV-2 positivity rate was 66.2%, with 99% of the positive samples showing an amplification profile consistent with that of the Omicron variant. Nasal Ag-RDT showed higher sensitivity (89%) than oral (12.6%) Ag-RDT. Our data showed good performance of the Ag-RDT in a pandemic scenario dominated by the Omicron VOC. Furthermore, our data also demonstrated that the Panbio COVID-19 antigen rapid diagnostic test does not provide good sensitivity with oral swabs for Omicron Ag-RDT detection.IMPORTANCE This study showed that the antigen rapid test for COVID19 worked fine using nasal swabs when it was utilized in patients infected with the Omicron variant, showing a concordance with PCR in 93% of patients tested. The nasal swab yielded more reliable results than the oral swab when an antigen rapid diagnosis test (the Panbio COVID-19 antigen rapid diagnostic test) was used in patients infected with the Omicron variant.

Rapid antigen test as a screening tool for SARS-CoV-2 infection: Head-to-head comparison with qRT-PCR in Ethiopia

Nucleic acid-based assays are the diagnostic gold standard for filoviruses, including Ebola (EBOV) and Sudan (SUDV) viruses. However, outbreaks in areas with limited laboratory infrastructure highlight the need for simpler diagnostic tests that can be rapidly and safely used in the field. We evaluated eight antigen rapid diagnostic tests (Ag-RDTs) for their ability to detect EBOV and SUDV. Analytical panels using virus cell slurries were used to assess limit of detection, and clinical samples were tested to determine sensitivity and specificity. Five Ag-RDTs detected EBOV and three detected SUDV, although clinical sensitivity was low (20-40% for EBOV, 33% for SUDV), improving only with higher viral loads. All assays demonstrated 100% clinical specificity with no cross-reactivity. Although none of the evaluated Ag-RDTs are suitable for routine diagnosis, some may be useful in high viral load contexts such as cadaver testing. Our findings highlight the need to improve Ag-RDT sensitivity or develop high-sensitivity point-of-care molecular diagnostics.

Determining the reliability of rapid SARS-CoV-2 antigen detection in fully vaccinated individuals.

Background: Infection with respiratory syncytial virus (RSV) in neonates is associated with significant morbidity and mortality. Early and accurate detection of RSV infection is important for appropriate isolation and cohorting, appropriate antibiotic usage, antiviral treatment, and public health awareness. However, RSV rapid antigen test performance has not been evaluated for neonates. Methods: A retrospective analysis of rapid RSV antigen testing in neonates (≤30 days) using a laboratory database of the Diagnostic Virology Laboratory at Texas Children's Hospital acquired between 1997 and 2008 was performed. Of 3691 respiratory samples collected consecutively, 784 (21%) were positive for RSV by rapid test and 402 (10.9%) showed growth of RSV in viral culture. Sensitivity, specificity, positive predictive values, and negative predictive values were calculated using viral culture as the reference standard. P values were calculated utilizing Pearson chi-square with SPSS Statistics 17.0. Result: Overall sensitivity was 90.3% and specificity was 88.2%. Sensitivity was lower in nonseason samples (76.5% vs. 90.9% [P = 0.048]), but specificity was higher in nonseason samples (95.6% vs. 87.1% [P ≤ 0.001]). Lower specificity was seen in samples submitted from neonates evaluated in the emergency department compared with inpatient floors, neonatal intensive care unit, and unspecified venues (85.1% vs. 95.6%, 94.3%, 95.5%, respectively P ≤ 0.001). Overall, there was no statistical difference in test performance based on specimen type. However, when RSV was in season, nasal washes were more sensitive than tracheal aspirates (P = 0.017). Conclusions: Rapid RSV antigen testing was sensitive and specific in detecting RSV infections in neonates. Moderate differences in test performance occurred in and out of RSV season, by sample type, and by the location within the hospital from where the sample was obtained.

ObjectivesWith the ongoing circulation of SARS-CoV-2 in countries across the world it is essential to identify effective ways to reduce the risk of infection while allowing society to function as close to ‘normal’ as possible. Serial testing using rapid lateral flow antigen tests is a possible way to do this by screening populations in a targeted way, identifying infectious (both symptomatic and asymptomatic) people and removing them from circulation while infectious. To make rapid antigen testing effective, high levels of participation are important. This study was designed to evaluate the establishment of a testing programme in a university setting and assess some of the factors that impact participation in such a study among both staff and students. Study designObservational, survey. MethodsA trial period of SARS-CoV-2 rapid testing using the Abbott Panbio rapid antigen test was set up and staff and students based in the University College Dublin Veterinary Hospital were asked to take part voluntarily for 6 weeks. Following the trial period, we used a questionnaire to evaluate satisfaction and to understand some reasons behind participation or lack thereof. ResultsOverall, almost all respondents to the survey stated that they were happy with having a testing programme present in the workplace and it helped to reduce anxiety associated with COVID-19. Findings indicated that staff and students did not participate equally in the voluntary testing programme. The findings also highlighted that intrinsic motivations and extrinsic motivations for participation differ. For example, participation among staff was much higher than among students, motivational messaging focused on protecting others did not resonate with students as much as staff, convenience was a key factor driving participation in both cohorts and the pressure of being forced to miss class (if positive) close to exam time provided motivation to students to avoid testing. ConclusionsIntroducing antigen testing into a workplace helped to reduce overall anxiety associated with the potential impact of COVID-19, but achieving good participation was challenging. Participation is key to a successful, campus wide antigen testing programme but reaching high levels of participation is not straightforward and can not be taken for granted. Different motivations drive participation in different cohorts and different messaging/incentivisation is needed to encourage participation in those different cohorts. The findings reported here should inform any SARS-CoV-2 testing programme that will run in these types of settings in the future.

Since late 2021, the variant landscape of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been dominated by the variant of concern (VoC) Omicron and its sublineages. We and others have shown that the detection of Omicron-BA.1 and -BA.2-positive respiratory specimens by rapid antigen tests (RATs) is impaired compared to Delta VoC-containing samples. Here, in a single-center retrospective laboratory study, we evaluated the performance of ten most commonly used RATs for the detection of Omicron-BA.4 and -BA.5 infections. We used 171 respiratory swab specimens from SARS-CoV-2 RNA-positive patients, of which 71 were classified as BA.4 and 100 as BA.5. All swabs were collected between July and September 2022. 50 SARS-CoV-2 PCR-negative samples from healthy individuals, collected in October 2022, showed high specificity in 9 out of 10 RATs. When assessing analytical sensitivity using clinical specimens, the 50% limit of detection (LoD50) ranged from 7.6 × 104 to 3.3 × 106 RNA copies subjected to the RATs for BA.4 compared to 6.8 × 104 to 3.0 × 106 for BA.5. Overall, intra-assay differences for the detection of these two Omicron subvariants were not significant for both respiratory swabs and tissue culture-expanded virus isolates. In contrast, marked heterogeneity was observed among the ten RATs: to be positive in these point-of-care tests, up to 443-fold (BA.4) and up to 56-fold (BA.5) higher viral loads were required for the worst performing RAT compared to the best performing RAT. True-positive rates for Omicron-BA.4- or -BA.5-containing specimens in the highest viral load category (Ct values < 25) ranged from 94.3 to 34.3%, dropping to 25.6 to 0% for samples with intermediate Ct values (25–30). We conclude that the high heterogeneity in the performance of commonly used RATs remains a challenge for the general public to obtain reliable results in the evolving Omicron subvariant-driven pandemic.

A prospective clinical evaluation of the diagnostic accuracy of the SARS-CoV-2 rapid antigen test using anterior nasal samples

BackgroundRapid antigen tests detecting SARS-CoV-2 were shown to be a useful tool in managing the COVID-19 pandemic. Here, we report on the results of a prospective diagnostic accuracy study of four SARS-CoV-2 rapid antigen tests in a South African setting.MethodsRapid antigen test evaluations were performed through drive-through testing centres in Durban, South Africa, from July to December 2021. Two evaluation studies were performed: nasal Panbio COVID-19 Ag Rapid Test Device (Abbott) was evaluated in parallel with the nasopharyngeal Espline SARS-CoV-2 Ag test (Fujirebio), followed by the evaluation of nasal RightSign COVID-19 Antigen Rapid test Cassette (Hangzhou Biotest Biotech) in parallel with the nasopharyngeal STANDARD Q COVID-19 Ag test (SD Biosensor). The Abbott RealTime SARS-CoV-2 assay was used as a reference test.ResultsEvaluation of Panbio and Espline Ag tests was performed on 494 samples (31% positivity), while the evaluation of Standard Q and RightTest Ag tests was performed on 539 samples (13.17% positivity). The overall sensitivity for all four tests ranged between 60 and 72% with excellent specificity values (> 98%). Sensitivity increased to > 80% in all tests in samples with cycle number value < 20. All four tests performed best in samples from patients presenting within the first week of symptom onset.ConclusionsAll four evaluated tests detected a majority of the cases within the first week of symptom onset with high viral load.

Due to the many technical limitations of molecular biology, the possibility to sustain enormous volumes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) diagnostic testing relies strongly on the use of antigen rapid diagnostic tests (Ag-RDTs). Besides a limited analytical sensitivity, the manually intensive test procedures needed forperforming these tests, very often performed by unskilled personnel or by the patients themselves, may contribute to considerably impair their diagnostic accuracy. We provide here an updated overview on the leading preanalytical drawbacks that may impair SARS-CoV-2 Ag-RDT accuracy, and which encompass lower diagnostic sensitivity in certain age groups, in asymptomatic subjects and those with a longertime from symptoms onset, in vaccine recipients, in individuals not appropriately trained to their usage, in those recently using oral or nasal virucidal agents, in oropharyngeal swabs and saliva, as well as in circumstances when instructions provided by the manufacturers are unclear, incomplete or scarcely readable and intelligible. Acknowledging these important preanalytical limitations will lead the way to a better, more clinically efficient and even safer use of this important technology, which represents an extremely valuable resource for management of the ongoing pandemic.

Background. Group A streptococcus (S. pyogenes) is responsi- ble for 5 – 20% of cases of pharyngitis in adults and 15 to 20% of cases in children. Most common diagnostic tests are throat culture and rapid antigen detection testing (RADT). The modified Centor criteria can be used to help physicians decide which patients need no testing, throat culture/rapid antigen detection testing or empiric antibiotic therapy. Objective. Evaluate the rapid group A streptococcus antigen test (RADT) usage and expediency in family physician practice. Goals. To analyze children aged between 3 - 15 who suffers from acute pharyngitis ≥ 3 times per year and have ≥ 3 modified Centor criteria; to evaluate the ease of use of RADT in family phy- sician practice; to identify the correlation between RADT and the clinical symptoms of the acute pharyngitis and between the RADT and the blood test results; to evaluate the importance of RADT in diagnosing the acute pharyngitis and choosing treatment strategy. Methods. The study was accomplished in 2011-2013. 108 children aged between 3 and 15 and who suffers from acute pha- ryngitis &gt; 2 times per year, plus have ≥ 3 modified Centor criteria were investigated. Prospectively all patients were tested by RADT. Also, the prescribed treatment and its effectiveness were analyzed. Statistical facts analysis was performed by using „SPSS 17.0“ and „MS Excel“ programs. Results. Girls suffer more often than boys from acute pha- ryngotonsillitis. The age average of patients was 7,22 ± 3,532. On average, patients appealed to doctor after 2-3 days of illness. RADT was positive in 32 (29.6%) children. Moreover, RADT was more often positive (42%) for children in 7-10 years old group, also for children who had 5 modified Centor criteria (62% of all positive cases). Conclusion. No statistically significant difference was obtained between the clinical symptoms and treatment effectiveness for children with a positive or negative result in RADT. However, all patients with positive RADT and who were taking Phenoxymethyl- penicillin recovered in 10 days. Moreover, obtained data shows that RADT test will facilitate the correct diagnosis and the tactics of selecting the treatment.

The COVID-19 pandemic continues to be a concern and keeps global health authorities on alert. The RT-PCR technique has been the gold-standard assay for detecting the SARS-CoV-2 virus. However, rapid antigen tests (RATs) have been widely used to increase the number of tests faster and more efficiently in the population. Nevertheless, the appearance of new viral variants, with genomic mutations associated with greater contagiousness and immune evasion, highlights the need to evaluate the sensitivity of these RATs. This report evaluates the sensitivity of SD Biosensor-Roche, Panbio™, and Clinitest® RATs widely used in Santiago de Chile in the detection of the Omicron variant from Nasopharyngeal samples (NPSs), the most predominant SARS-CoV-2 variant in Chile and the world. SD Biosensor-Roche shows a detection sensitivity of 95.7% in the viral amplification range of 20 ≤ Cq < 25, while Panbio™ and Clinitest® show 100% and 91.3%, respectively. In the viral amplification ranges of 25 ≤ Cq < 30, the detection sensitivity decreased to 28% for SD Biosensor-Roche, 32% for Panbio™, and 72% for Clinitest®. This study indicates that the tested RATs have high sensitivity in detecting the Omicron variant of concern (VOC) at high viral loads. By contrast, its sensitivity decreases at low viral loads. Therefore, it is suggested to limit the use of RATs as an active search method, considering that infections in patients are increasingly associated with lower viral loads of SARS-CoV-2. These antecedents could prevent contagion outbreaks and reduce the underestimation of the current Omicron variant circulation at the local level.

Individuals infected with the provincially and globally dominant SARS-CoV-2 Delta variant demonstrate viral loads that peak sooner after exposure compared to those infected with previous strains of SARS-CoV-2. High SARS-CoV-2 viral loads are likely present before symptoms. These characteristics make the Delta variant challenging to control; however, they may also improve the performance and expand the practical utility of rapid antigen tests. In this Science Brief, we determined whether cases with high viral loads/low cycle thresholds are likely to be infectious, and if so, whether rapid antigen tests can reliably detect those cases. Voluntary screen testing entails regular voluntary testing of asymptomatic individuals to find cases in moderate-risk settings such as schools and workplaces. We found that rapid antigen tests can be a useful tool to reduce transmission in schools when used for voluntary screen testing to identify infectious cases in Public Health Units or neighborhoods using the following thresholds: Once a Public Health Unit or neighborhood approaches 50 new COVID-19 cases per million per day (corresponding to 35 cases per 100,000 per week) and is in sustained exponential growth, we advise weekly voluntary screen testing of unvaccinated and incompletely vaccinated individuals in elementary schools. Public health units in this situation may also decide to deploy rapid antigen testing in other settings, such as workplaces and congregate settings. If a Public Health Unit’s or neighborhood’s new daily case rate approaches 250 COVID-19 cases per million per day (corresponding to 175 cases per 100,000 per week), weekly testing is likely not frequent enough to reduce spread effectively. In that case, we advise testing unvaccinated and incompletely vaccinated individuals 2 to 3 times per week. Public health units in this situation may also consider voluntary screen testing of fully vaccinated individuals at the same frequency. Rapid antigen tests may also present a valuable alternative to individual isolation after exposure in schools. Implementing voluntary “test to stay” protocols, where exposed students remain in school as long as daily tests are negative for SARS-CoV-2, could help prevent the harms of isolation without increasing transmission. Individuals with positive rapid antigen tests should immediately isolate and undergo confirmatory Polymerase Chain Reaction (PCR) testing. Evaluation of the performance of rapid antigen tests for the diagnosis of the Omicron variant is urgently needed.

Association between rapid antigen detection tests and antibiotics for acute pharyngitis in Japan: A retrospective observational study.