Antigen Rapid Diagnostic Tests Research Articles

Pilot deployment of a community health care worker in distributing and offering the COVID-19 AgRDT in Tanzania.

A pilot implementation of the rapid diagnostic test program was performed to collect evidence of the feasibility, acceptability, and uptake of the COVID-19 AgRDT in Tanzania. We conducted a prospective cross-sectional study in the community to provide quantitative details of the pilot implementation of the antigen rapid diagnostic test (AgRDT) in Tanzania. This study was undertaken between March 2022 and September 2022. The pilot was implemented by distributing and offering test kits to people suspected of having COVID-19 in Dar es Salaam through community health workers. A total of 1039 participants consented to participate in the survey. All the participants reported having heard about the disease. The radio was the main source (93.2%) of information on COVID-19. With regard to prevention measures, approximately 930 (89.5%) of the respondents thought that COVID-19 could be prevented. Approximately 1035 (99.6%) participants reported that they were willing to have a COVID-19 AgRDT test and wait for 20 min for the results. With regard to the participants' opinions on the AgRDT device, the majority 907 (87.3%) felt comfortable with the test, and 1,029 (99.0%) were very likely to recommend the AgRDT test to their friends. The majority of participants 848 (83.1%) mentioned that they would be willing to pay for the test if it was not available for free. The results suggest overall good acceptance of the COVID-19 AgRDT test. It is evident that the use of trained community healthcare workers allows easy screening of all possible suspects and helps them receive early treatment.

Performance characteristics of INDICAID antigen rapid diagnostic test on SARS-CoV-2 samples during the omicron wave in Cameroon

BackgroundWHO recommends the use of COVID-19 antigen rapid diagnostic tests (Ag-RDT) with at least 80 % sensitivity and 97 % specificity. In the era of Omicron variants, we sought to ascertain the performance of the INDICAID™ Ag-RDT compared to real-time PCR (RT-PCR) as the gold standard. MethodsA laboratory-based study was conducted among consenting individuals tested for COVID-19 at the virology laboratory of the Chantal BIYA International Reference Centre, Yaoundé-Cameron. The samples were processed by INDICAID™ Ag-RDT and DaAn Gene real-time PCR according to the manufacturer's instructions, and PCR-results were interpreted as per cycle thresholds (CT). The sensitivity, specificity, positive and negative predictive values (PPV and NVP) of INDICAID™ Ag-RDT were evaluated according to PCR CT-values. ResultsA total of 565 nasopharyngeal swabs were collected from participants (median age [IQR]: 40 [31–75]; M/F sex-ratio was 1.2 and 380 were vaccinated). Following PCR, overall COVID-19 positivity was 5.66 %. For CT < 37, INDICAID™ Ag-RDT sensitivity was 21.9 % (95%CI: [8.3–39.9]), specificity 100 % (95%CI: [99.3–100]); PPV 100 % (95%CI: [59.0–100]), NPV 95.5 % (95%CI: [93.4–97.1]) and kappa = 0.34 (95%CI: [0.19–0.35]). For CT < 25, sensitivity was 100 % (95%CI: [47.8–100.0]), specificity 99.6 % (95%CI: [98.7–99.9]); PPV 94.4 % (95%CI: [51.7–100]), NPV 100 % (95%CI: [99.3–100]) and kappa = 0.83 (95%CI: [0.6–1.0]). COVID-19 sequences generated were all Omicron BA.1 subvariants. ConclusionFor patients infected with high viral loads (CT < 25), INDICAID™ Ag-RDT has high intrinsic (sensitivity and specificity) and extrinsic (predictive values) performances for COVID-19 diagnosis. Due to its simplicity and short turnaround time, INDICAID™ Ag-RDT is, therefore a reliable tool to prevent the spread of COVID-19 at community level in the current era of Omicron subvariants.

The Significance of TNF-α, CRP, and Hematological Parameters in the Prediction of Plasmodium Falciparum Parasitemia

Malaria remains a significant public health concern in Sudan, with Plasmodium falciparum (P. falciparum) infection having widespread indirect consequences. Effective identification of infection severity is crucial for preventing complications. This study aimed to assess the predictive value of Tumor Necrosis Factor Alpha (TNF-α), C-reactive protein (CRP), and hematological parameters in P. falciparum parasitemia. The three-month cross-sectional study involved 54 P. falciparum-positive patients at Bashaire Teaching Hospital Khartoum, Sudan, along with an equal number of P. falciparum-negative individuals. Participants underwent Antigen Rapid Diagnostic Test (RDT), TNFα, CRP, and Complete Blood Count (CBC) assessments. The infected group comprised 68.5% male patients, with a mean age of 22.3 years. Significant variations were observed between the infected and uninfected groups in TNFα, CRP, Total White Blood Cells (TWBCs), and neutrophil levels, with infected individuals showing higher values. Conversely, infected individuals had lower hemoglobin, Red Blood Cells (RBCs), Mean Corpuscular Volume (MCV), Mean Corpuscular Hemoglobin (MCH), Mean Corpuscular Hemoglobin Concentration (MCHC), platelets, and lymphocytes. The study revealed a noteworthy association between MCV and parasitemia, while TNFα, CRP, Hb, RBCs, MCH, and MCHC showed no significant correlation. Hematological parameters should be considered in malaria patients.

Costs of integrating hepatitis B screening and antiviral prophylaxis into routine antenatal care in Burkina Faso: Treat all versus targeted strategies.

Economic feasibility of eliminating mother-to-child transmission (MTCT) of hepatitis B virus (HBV) in highly endemic African countries remains uncertain. Prevention of MTCT (PMTCT) involves screening pregnant women for hepatitis B surface antigen (HBsAg), identifying those with high viral loads or hepatitis B e antigen (HBeAg), and administering tenofovir prophylaxis to high-risk women. We estimated the costs of integrating PMTCT services into antenatal care in Burkina Faso, based on four different strategies to select women for tenofovir prophylaxis: (1) HBV DNA (≥200 000 IU/mL), (2) HBeAg, (3) hepatitis B core-related antigen rapid diagnostic test (HBcrAg-RDT) and (4) all HBsAg-positive women. Using a micro-costing approach, we estimated the incremental economic cost of integrating each strategy into routine antenatal care in 2024, compared to neonatal vaccination alone. Sensitivity analyses explored variations in prevalence, service coverage, test and tenofovir prices. HBcrAg-RDT strategy was the least expensive, with a total economic cost of US$3959689, compared to HBV DNA (US$6128875), HBeAg (US$4135233), and treat-all (US$4141206). The cost per pregnant woman receiving tenofovir prophylaxis varied from US$61.88 (Treat-all) to US$1071.05 (HBV DNA). The Treat-All strategy had the lowest marginal cost due to a higher number of women on tenofovir (66928) compared to HBV DNA (5722), HBeAg (10020), and HBcrAg-RDT (7234). In sensitivity analyses, the treat-all strategy became less expensive when the tenofovir price decreased. HBcrAg-RDT minimizes resource use and costs, representing 0.61% of Burkina Faso's 2022 health budget. This study highlights the potential economic feasibility of these strategies and provides valuable resources for conducting cost-effectiveness analyses.

Evaluation of COVID-19 antigen rapid diagnostic tests for self-testing in Lesotho and Zambia.

The use of antigen rapid tests (Ag-RDTs) for self-testing is an important element of the COVID-19 control strategy and has been widely supported. However, scale-up of self-testing for COVID-19 in sub-Saharan Africa is still insufficient and there is limited evidence on the acceptability of self-testing and agreement between Ag-RDT self-testing and Ag-RDT testing by professional users. A joint collaboration (Botnar Research Centre for Child Health-European & Developing countries Clinical Trials Partnership)was established between Lesotho and Zambia to address these gaps in relation to Ag-RDT self-testing and contribute to increasing its use in the region. A cross-sectional study was conducted with qualitative and quantitative data analysis. Firstly, 14 in-depth cognitive interviews (5 in Zambia and 9 in Lesotho) were performed to assess the participants' understanding of the instructions for use (IFU) for self-testing. In a second step, evaluation of test agreement between Ag-RDT self-testing and Ag-RDT testing by professional user using SD Biosensor STANDARD Q COVID-19 Ag-RDT was performed. In Zambia, usability and acceptability of self-testing were also assessed. Cognitive interviews in Lesotho and Zambia showed overall good understanding of IFU. In Zambia, acceptability of self-testing was high, though some participants had difficulties in conducting certain steps in the IFU correctly. Agreement between Ag-RDT self-test and Ag-RDT by professional users in Lesotho (428 participants) and Zambia (1136 participants) was high, 97.3% (403/414, 95% CI: 95.3-98.7) and 99.8% (1116/1118, 95% CI: 99.4-100) respectively. Findings from this study support the use of Ag-RDT self-testing within COVID-19 control strategies in sub-Saharan Africa, contributing to increase the testing capacity and access in hard-to reach settings.

The diagnostic performance evaluation of Panbio and STANDARD Q coronavirus disease 2019 antigen tests against real-time polymerase chain reaction in southern Ethiopia

The coronavirus disease 2019 (COVID-19) pandemic has created a public health crisis. This study aimed to evaluate the diagnostic performance of the Panbio and STANDARD Q COVID-19 antigen rapid diagnostic tests (RDTs) against the real-time polymerase chain reaction (RT-PCR) at one of the largest hospitals in southern Ethiopia. Nasopharyngeal samples, which were collected during the pandemic from individuals suspected of COVID-19 and stored at − 70 °C, were analyzed in June and July 2022. The performance of the Panbio COVID-19 antigen tests was evaluated in 200 randomly selected nasopharyngeal samples (100 positives and 100 negatives for severe acute respiratory syndrome 2 by RT-PCR). The STANDARD Q test was evaluated using 100 positive and 50 negative samples. The respective sensitivity, specificity, positive predictive value and negative predictive values were 88%, 99%, 98.9% and 89.2% for the Panbio test and 91%, 98%, 98.9% and 84.5%, for the STANDARD Q test. The kappa values were 0.87 for the Panbio and 0.86 for the STANDARD Q test. Based on the findings presented here, the RDTs could be utilized as an alternative to conventional RT-PCR when it is challenging to diagnose COVID-19 owing to a lack of time, skilled lab personnel, or suitable equipment or electricity.

Access to and utilization of COVID-19 antigen rapid diagnostic tests (Ag-RDTs) among people living with HIV (PLWH): A mixed methods study from Cambodia.

Several COVID-19 antigen rapid diagnostic tests have been approved in Cambodia, but no evidence exists about the access to and utilization of these tests. This limits public health interventions to increase testing, especially among vulnerable populations such as people living with HIV (PLWH). We conducted a mixed method study among PLWH in Phnom Penh, Cambodia, between July and August 2022 to understand their current Ag-RDT access and utilization levels, as well as key barriers and drivers. We undertook a cross-sectional survey and focus group discussions among 280 and 10 PLWH, respectively, from five HIV treatment centres using a probability-proportional-to-size and simple random sampling approach. Access was defined as having received a COVID-19 Ag-RDT within the six months and utilization as having administered a COVID-19 Ag-RDT, either to oneself or to others, within the 12 months prior to the study. We calculated means, standard deviations and proportions for continuous and categorical variables, using a linear regression model with random effects to account for clustering. Additionally, we fitted a logistic model with random effects to assess factors associated with Ag-RDT access. For the qualitative data, we used thematic analyses to identify barriers/enablers of Ag-RDT access and utilization. About 35% (n = 101) of PLWH reported having had access to an Ag-RDT test in the past six months. About 11% (n = 32) of the study participants administered the Ag-RDT to themselves, 4% (n = 10) to others and 9% (n = 24) have done both, in the past 12 months. Age and education appeared to be associated with Ag-RDT access in the logistic models. Price and advice from pharmacists were commonly reported to be the main selection criteria for the brand of Ag-RDT chosen. Ag-RDTs are an important diagnostic tool for COVID-19 among PLWH in Cambodia, but familiarity of use and price could hinder better uptake, access and utilization.

Simultaneous Detection of Infectious Diseases Using Aptamer-Conjugated Gold Nanoparticles in the Lateral Flow Immunoassay-Based Signal Amplification Platform.

Various platforms for the accurate diagnosis of infectious diseases have been studied because of the emergence of coronavirus disease (COVID-19) in 2019. Recently, it has become difficult to distinguish viruses with similar symptoms due to the continuous mutation of viruses, and there is an increasing need for a diagnostic method to detect them simultaneously. Therefore, we developed a paper-based rapid antigen diagnostic test using DNA aptamers for the simultaneous detection of influenza A, influenza B, and COVID-19. Aptamers specific for each target viral antigen were selected and attached to AuNPs for application in a rapid antigen diagnosis kit using our company's heterogeneous sandwich-type aptamer screening method (H-SELEX). We confirmed that the three viruses could be detected on the same membrane without cross-reactivity based on the high stability, specificity, and binding affinity of the selected aptamers. Further, the limit of detection was 2.89 pg·mL-1 when applied to develop signal amplification technology; each virus antigen was detected successfully in diluted nasopharyngeal samples. We believe that the developed simultaneous diagnostic kit, based on such high accuracy, can distinguish various infectious diseases, thereby increasing the therapeutic effect and contributing to the clinical field.

Temporal Trend of the SARS-CoV-2 Omicron Variant and RSV in the Nasal Cavity and Accuracy of the Newly Developed Antigen-Detecting Rapid Diagnostic Test.

The aim of this work is to analyze the viral titers of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and respiratory syncytial virus (RSV) at the anterior nasal site (ANS) and nasopharyngeal site (NS), evaluate their virological dynamics, and validate the usefulness of a newly developed two-antigen-detecting rapid antigen diagnostic test (Ag-RDT) that simultaneously detects SARS-CoV-2 and RSV using clinical specimens. This study included 195 asymptomatic to severely ill patients. Overall, 668 specimens were collected simultaneously from the ANS and NS. The cycle threshold (Ct) values calculated from real-time polymerase chain reaction were used to analyze temporal changes in viral load and evaluate the sensitivity and specificity of the Ag-RDT. The mean Ct values for SARS-CoV-2-positive, ANS, and NS specimens were 28.8, 28.9, and 28.7, respectively. The mean Ct values for RSV-positive, ANS, and NS specimens were 28.7, 28.8, and 28.6, respectively. SARS-CoV-2 and RSV showed the same trend in viral load, although the viral load of NS was higher than that of ANS. The sensitivity and specificity of the newly developed Ag-RDT were excellent in specimens collected up to 10 days after the onset of SARS-CoV-2 infection and up to 6 days after the onset of RSV infection.

Development and Clinical Performance of InteliSwab® COVID-19 Rapid Test: Evaluation of Antigen Test for the Diagnosis of SARS-CoV-2 and Analytical Sensitivity to Detect Variants of Concern Including Omicron and Subvariants.

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. 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. 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.

Clinical course and complications of RSV versus non-RSV bronchiolitis in hospitalised children

Introduction and objective: Bronchiolitis in young children often requires hospitalisation. It is mostly caused by respiratory syncytial virus (RSV) and aetiological factors may be associated with clinical presentation and prognosis. We aimed to compare the epidemiology, clinical features, severity and management of RSV and non-RSV bronchiolitis. Materials and methods: This cross-sectional retrospective study included hospitalised children under 2 years of age. Children with a positive rapid antigen diagnostic test and/or molecular study were included in the RSV group, while those with a negative result were classified as non-RSV bronchiolitis. We compared patient history, clinical presentation, disease severity including passive oxygen therapy, intensive care unit transfer, death, length of hospital stay, presence of complications, oxygen saturation &lt;92%, acidosis, hypercapnia and treatment used. Results: The study included 524 patients (median age 2 months): 462 (88%) RSV and 62 (12%) non-RSV cases. A 7-fold increase in the number of cases was observed between 2010–2011 and 2017–2018. A univariate regression model showed lower odds of family history of atopy (odds ratio, OR = 0.46), higher odds of cough (OR = 4.74), apathy (OR = 2.61), feeding difficulties (OR = 2.03) and vomiting (OR = 3.34) in the RSV group. RSV patients required oxygen therapy (OR = 3.78) and antibiotics (OR = 2.82) more frequently, received inhaled steroid therapy for longer (9 vs. 8 days) and had a higher likelihood of complications (OR = 4.24). A multivariate model showed statistical significance for cough (OR = 6.22), oxygen therapy (OR = 4.43) and complications (OR = 15.95). Conclusions: We observed an increasing trend in bronchiolitis hospitalisations, including RSV bronchiolitis, which was associated with a more severe disease course. No significant clinical features were identified to replace laboratory tests.

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

ObjectiveThis study aimed to determine the diagnostic accuracy of the antigen rapid diagnostic test (Ag-RDT) as a screening tool for SARS-CoV-2 infection compared to Quantitative reverse transcription polymerase chain reaction (qRT-PCR). MethodsThis study was conducted at six referral hospitals in Oromia Region, Ethiopia. One thousand seven hundred twenty-one patients who visited the hospitals for various medical conditions were tested with qRT-PCR and/or Ag-RDTs. Qualitative detection of SARS-CoV-2 antigen was performed using the Panbio™ COVID-19 Ag rapid test device. ResultsCompared with qRT-PCR, Ag-RDTs had a sensitivity of 33.3 % (95%CI: 30.9%–35.9 %) and a specificity of 99.3 % (95%CI: 98.8%–99.7 %) to detect active SARS-CoV-2 infection. The area under the receiver operator curve was 0.67 (95%CI: 0.63–0.69). The sensitivity of Ag-RDTs appeared high in patients with shortness of breath (73.3 %) and those presenting with all three symptoms – fever, cough, and dyspnea (71.4 %). In all instances, specificity was more than 98 %. The Ag-RDT positivity rate also correlated well with viral load: 51.7 % in cases with cycle threshold (Ct) < 25 (high viral load) and only 3.4 % when Ct > 25 (low viral load). ConclusionAlthough Ag-RDT for diagnosing SARS-CoV-2 is a good option as a point-of-care screening tool, it has a low sensitivity to detect active infections. Using Panbio™ COVID-19 Ag Rapid test for diagnostic and treatment decisions may lead to a false negative, resulting in patient misdiagnosis, ultimately contributing to disease spread and poor patient outcome.

SARS-CoV-2 rapid antigen testing positive rate in community testing stations as an indicator for COVID-19 epidemic trend, Taipei, Taiwan, May to August 2021

BackgroundReal-time surveillance of COVID-19 in large-scale community outbreaks presents challenges. Simple counts of the daily confirmed cases can be misleading due to constraints from bottlenecks in access to care or laboratory testing. This study aimed to investigate the role of the SARS-CoV-2 antigen rapid diagnostic test (Ag-RDT) in addressing these challenges for real-time COVID-19 surveillance. MethodsThis study included the results of 86,933 SARS-CoV-2 Ag-RDT and real-time reverse transcription polymerase chain reaction (RT-PCR) tests. These were conducted at four community testing stations within the Taipei metropolitan area during a community COVID-19 outbreak spanning from May 17, 2021, to August 9, 2021. We examined the correlation between the positive rates of Ag-RDT tests and the epidemic curve of laboratory-confirmed COVID-19 cases by onset date to examine its role in real-time surveillance. ResultsDuring the 85-day study period, the trend of Ag-RDT test positive rates paralleled that of the epidemic curve. The correlation between the Ag-RDT positive rate and the number of cases (Pearson correlation coefficient: 0.968) is comparable to that of the RT-PCR positive rate (Pearson correlation coefficient: 0.964). The Ag-RDT positive rate exhibited a more advanced leading trend, with Ag-RDT leading by 3 days in comparison to the 2-day lead for RT-PCR. ConclusionThe positive rate of SARS-CoV-2 Ag-RDT tests at community testing stations serves as a good surrogate for assessing virus activity within the community and a useful tool for real-time COVID-19 surveillance. It is a robust indicator of the outbreak trend and near-term numbers of cases. This finding may facilitate the management of subsequent outbreaks of emerging infectious diseases.

Clinical evaluation of a new COVID-19 antigen rapid test kit for detection of SARS-CoV-2

The antigen rapid diagnostic test (Ag-RDT) is an assay kit for detecting the SARS-COV-2 nucleocapsid proteins, based on the colloidal gold method.Accurate diagnosis has an important role in limiting the transmission of SARS-COV-2, and also helps patients to receive earlier treatment .The object of this study was to perform the clinical evaluation of a novel Ag-RDTs with samples collected from two different swabs.DEEPBLUE®COVID-19 antigen detection kit used for the examination of the subjects in the experiment.For antigen testing on samples collected with nasal swabs, sensitivity was 91.7 % (95 % CI 83.6-96.6 %) and specificity was 100 %(95 %CI 98.1-100 %).For nasopharyngeal swabs, the sensitivity was 96.8 % (95 % CI 93.6-98.7 %) and the specificity was 100 % (95 % CI 98.2-100 %).Fisher Precision test showed a significant correlation between nasopharyngeal swab Ag-RDTs and nasal swab Ag-RDTs and RT-qPCR test (p-value <0.001).The results showed that the patients use the kit for testing were comparable to the RT-qPCR.

Direct Dengue Virus Genome Sequencing from Antigen NS1 Rapid Diagnostic Tests: A Proof-of-Concept with the Standard Q Dengue Duo Assay.

With nearly half of the world's population being at risk of infection, dengue virus represents a major global health issue. The use of dengue antigen rapid diagnostic tests (Ag-RDTs) represents an alternative to PCR methods for the diagnosis of acute infections since they display excellent sensitivities and specificities and can be performed outside the laboratory. The high genetic diversity of the dengue virus genome represents a challenge for vaccine development, and the progressive expansion of this virus into previously nonendemic regions justifies the implementation of a genomic surveillance program. In this proof-of-concept study, we show the feasibility of sequencing dengue virus genomes directly from positive Ag-RDT (Standard Q Dengue Duo Test assay, n = 7) cassettes stored up to 31 days at room temperature after testing. For 5 of the 7 samples, a high number of reads were obtained allowing phylogenetic analyses to be carried out to determine not only the serotypes (dengue 1, 2, 3 and 4 were detected) but also the genotypes. Furthermore, in one sample, our unbiased metagenomic next-generation sequencing approach made it possible to detect epizootic hemorrhagic disease virus sequences, an arthropod-transmitted virus in ruminants. To conclude, as such an approach requires no cold storage or freezing of samples, dengue Ag-RDTs represent a very pragmatic and robust alternative for the genomic surveillance of dengue virus.

SARS-CoV-2 Rapid Antigen Test Based on a New Anti-Nucleocapsid Protein Monoclonal Antibody: Development and Real-Time Validation.

SARS-CoV-2 diagnostic tests have become an important tool for pandemic control. Among the alternatives for COVID-19 diagnosis, antigen rapid diagnostic tests (Ag-RDT) are very convenient and widely used. However, as SARS-CoV-2 variants may continuously emerge, the replacement of tests and reagents may be required to maintain the sensitivity of Ag-RDTs. Here, we describe the development and validation of an Ag-RDT during an outbreak of the Omicron variant, including the characterization of a new monoclonal antibody (anti-DTC-N 1B3 mAb) that recognizes the Nucleocapsid protein (N). The anti-DTC-N 1B3 mAb recognized the sequence TFPPTEPKKDKKK located at the C-terminus of the N protein of main SARS-CoV-2 variants of concern. Accordingly, the Ag-RDT prototypes using the anti-DTC-N 1B3 mAB detected all the SARS-CoV-2 variants-Wuhan, Alpha, Gamma, Delta, P2 and Omicron. The performance of the best prototype (sensitivity of 95.2% for samples with Ct ≤ 25; specificity of 98.3% and overall accuracy of 85.0%) met the WHO recommendations. Moreover, results from a patients' follow-up study indicated that, if performed within the first three days after onset of symptoms, the Ag-RDT displayed 100% sensitivity. Thus, the new mAb and the Ag-RDT developed herein may constitute alternative tools for COVID-19 point-of-care diagnosis and epidemiological surveillance.

The New Normal: Delayed Peak SARS-CoV-2 Viral Loads Relative to Symptom Onset and Implications for COVID-19 Testing Programs.

Early in the coronavirus disease 2019 (COVID-19) pandemic, peak viral loads coincided with symptom onset. We hypothesized that in a highly immune population, symptom onset might occur earlier in infection, coinciding with lower viral loads. We assessed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza A viral loads relative to symptom duration in symptomatic adults (≥16 years) presenting for testing in Georgia (4/2022-4/2023; Omicron variant predominant). Participants provided symptom duration and recent testing history. Nasal swabs were tested by Xpert Xpress SARS-CoV-2/Flu/RSV assay and cycle threshold (Ct) values recorded. Nucleoprotein concentrations in SARS-CoV-2 polymerase chain reaction (PCR)-positive samples were measured by single molecule array. To estimate hypothetical antigen rapid diagnostic test (Ag RDT) sensitivity on each day after symptom onset, percentages of individuals with Ct value ≤30 or ≤25 were calculated. Of 348 newly-diagnosed SARS-CoV-2 PCR-positive individuals (65.5% women, median 39.2 years), 317/348 (91.1%) had a history of vaccination, natural infection, or both. By both Ct value and antigen concentration measurements, median viral loads rose from the day of symptom onset and peaked on the fourth/fifth day. Ag RDT sensitivity estimates were 30.0%-60.0% on the first day, 59.2%-74.8% on the third day, and 80.0%-93.3% on the fourth day of symptoms.In 74 influenza A PCR-positive individuals (55.4% women; median 35.0 years), median influenza viral loads peaked on the second day of symptoms. In a highly immune adult population, median SARS-CoV-2 viral loads peaked around the fourth day of symptoms. Influenza A viral loads peaked soon after symptom onset. These findings have implications for ongoing use of Ag RDTs for COVID-19 and influenza.

Diagnostic evaluation of Panbio™ antigen rapid diagnostic test for SARS‐CoV‐2: A systematic review and meta-analysis

IntroductionThe reverse transcriptase polymerase chain reaction (RT-PCR) is the reference diagnostic method for the confirmation of SARS-CoV-2 infected cases. However, various antigen rapid diagnostic tests (Ag-RDTs) have been developed. The purpose of this meta-analysis study was to assess the diagnostic performance of Panbio™ Ag-RDT (Abbott Point of Care) in identifying the SARS-CoV-2 virus. MethodsWe systematically searched eight databases from March 2020 until March 2023 to look for potentially eligible articles. Diagnostic meta-analysis of Panbio™ Ag-RDT used diverse evaluation indicators, including sensitivity, specificity, Diagnostic Odds Ratio (DOR), and the area under the curve (AUC) value. ResultsOf the 794 articles identified, 49 studies met the inclusion criteria. The pooled estimates of Panbio™ Ag-RDT for the diagnosis of SARS-CoV-2 were 0,65 (95% CI: 0,64–0,66), 0,99 (95% CI: 0,99–1,00), 578,03 (95% CI: 333,37–1002,26) for sensitivity, specificity, and DOR, respectively. Moreover, the summary receiver operating characteristic (SROC) curve revealed an AUC value of 0,942 (95% CI: 0,941–0,943), suggesting an outstanding diagnostic accuracy. Subgroup and meta-regression analyses showed that continent, study period, age, study population and cycle threshold (Ct) values constituted a source of heterogeneity. Furthermore, we demonstrated proof of publication bias for DOR values analyzed using Deek’s test (p = 0,001) and funnel plot. ConclusionPanbio™ Ag-RDT presented an outstanding diagnostic accuracy in the detection of the SARS-CoV-2 virus in both adults and children with or without symptoms.

Nationwide survey on the management of pediatric pharyngitis in Italian emergency units

BackgroundAcute pharyngitis is a frequent reason for primary care or emergency unit visits in children. Most available data on pharyngitis management come from primary care studies that demonstrate an underuse of microbiological tests, a tendency to over-prescribe antibiotics and a risk of antimicrobial resistance increase. However, a comprehensive understanding of acute pharyngitis management in emergency units is lacking. This study aimed to investigate the frequency of rapid antigen test use to diagnose acute pharyngitis, as well as other diagnostic approaches, the therapeutic attitude, and follow-up of children with this condition in the emergency units.MethodsA multicentric national study was conducted in Italian emergency departments between April and June 2022.ResultsA total of 107 out of 131 invited units (response rate 82%), participated in the survey. The results showed that half of the units use a scoring system to diagnose pharyngitis, with the McIsaac score being the most commonly used. Most emergency units (56%) were not provided with a rapid antigen diagnostic test by their hospital, but the test was more frequently available in units visiting more than 10,000 children yearly (57% vs 33%, respectively, p = 0.02). Almost half (47%) of the units prescribe antibiotics in children with pharyngitis despite the lack of microbiologically confirmed cases of Group A β-hemolytic streptococcus. Finally, about 25% of units prescribe amoxicillin-clavulanic acid to treat Group A β-hemolytic streptococcus pharyngitis.ConclusionsThe study sheds light on the approach to pharyngitis in emergency units, providing valuable information to improve the appropriate management of acute pharyngitis in this setting. The routinary provision of rapid antigen tests in the hospitals could enhance the diagnostic and therapeutic approach to pharyngitis.

Diagnostic accuracy of a rapid antigen triple test (SARS-CoV-2, respiratory syncytial virus, and influenza) using anterior nasal swabs versus multiplex RT-PCR in children in an emergency department

BackgroundIn children, respiratory infections such as SARS-CoV-2, respiratory syncytial virus (RSV), and influenza share similar clinical signs and symptoms. Here we compared the performance of a rapid antigen diagnostic test using a self-collected anterior nasal swab (COVID-VIRO ALL IN TRIPLEX) and multiplex RT-PCR. MethodsFrom October to December 2022, in the emergency pediatrics unit of Orleans Hospital, France, we evaluated the diagnostic accuracy of the triplex test. ResultsFor the 263 children, sensitivity of the test was 88.9% (95%CI 51.8–99.7), 79.1% (95%CI 64.0–90.0), and 91.6% (95%CI 84.1–96.3), for SARS-CoV-2, RSV, and influenza, respectively. Specificity was 100% for each virus. For RT-PCR with cycle threshold < 32, sensitivity was 100.0% [95%CI 59.0–100.0], 87.2% [95%CI 72.6–95.7] and 92.3% [95%CI 84.896.9] for SARS-CoV-2, RSV, and influenza respectively. ConclusionsThis easy-to-perform triplex test is a considerable advance, allowing clinicians to obtain an accurate diagnosis in most cases of respiratory infection. More data are needed to validate this test in different contexts and across several seasons.