Antigen Rapid Diagnostic Tests Research Articles

Community case study for surveillance and early case-detection of SARS-CoV-2 infections across high-risk key populations: the Sentinella programme.

At the beginning of the COVID-19 pandemic, an ad hoc organisational framework was established between academic, local government and community partners to implement the "Sentinella - Identify, Trace and Prevent" screening programme in Verona, north-east Italy. Between September 2020 and May 2021, key populations not covered by any screening policies at the local and national level were screened for SARS-CoV-2. Target populations were: older adult residents (males >65 years and females >75 years), bus and taxi drivers, social workers, supermarket employees, hospital cleaning and catering staff, researchers working in the local hospitals, students, and people experiencing homelessness (PEH). Five dedicated swab clinics, home testing facilities, and one mobile clinic were activated to collect nasopharyngeal swabs. Molecular analysis was performed for all the subjects; an antigen-rapid diagnostic test (Ag-RDT) was also implemented as a point-of-care test for PEH. Medical follow-up, psychological support, and quarantine facilities were organised for subjects who tested positive for SARS-CoV-2. Overall, 2075 subjects participated in the surveillance programme. Amongst these, 1,572 were residents/workers, whilst 503 were PEH. A total of 127 (6.2%) participants tested positive for SARS-CoV-2. Sixty-nine were residents, 58 PEH. The incidence rate was 4 per 10.000 person/day (95% CI 3.1-5.0). The highest prevalence and incidence rates were found amongst supermarket employees (9.7% and 8.5 per 10.000 person/day, 95% CI 3.81-18.86, respectively), followed by hospital cleaning staff (8.1%, 7.6 per 10.000 person/day, CI 95% 4.9-11.7). Regarding PEH, the prevalence of SARS-CoV-2 was 11.5%. All PEH identified as positive were isolated in dedicated shelter facilities. Amongst the 69 residents/workers who were quarantined, 53 were reached for initial psychological support for assessing the presence of any psychological distress or psychiatric pathology. Amongst the subjects evaluated, 10 (18.9%) presented clinically significant psychological discomfort and accessed the stepped-care psychological intervention. The community partnerships played a pivotal role in optimising early case detection. Promotion of testing helped to prevent and contain more efficiently potential clusters through strategic planning, especially for PEH. Insights from the study highlight the importance of community partnerships in public health emergencies, particularly in the context of highly transmissible diseases pathways.

Uptake, Acceptability, and Results of SARS-CoV-2 Antigen Rapid Diagnostic Testing in Community Settings in Cameroon.

Mass gathering event restrictions were part of mitigation measures during the COVID-19 pandemic that were lifted as prevalence decreased and after vaccination rollout. We explored SARS-CoV-2 antigen rapid diagnostic test acceptability and positivity in community settings in Cameroon. In August-October 2022, community workers sensitized and referred individuals for COVID-19 testing to nearby testing points in Douala and Yaoundé. Participants consented to SARS-CoV-2 antigen rapid diagnostic testing, a survey, or both components. We describe the positivity rate, COVID-19-related history, and Likert-scale testing perceptions. Factors associated with testing acceptance were analyzed using logistic regression. Overall, 20.5% (2,449/11,945) of sensitized individuals visited testing points, and 1,864 (76.1%) were enrolled; 50.6% accepted the survey and testing (46.0% accepted survey only). Seven (0.7%) of 1,006 individuals tested positive. Most (71.8%; 1,292/1,800) considered community testing more accessible than hospital-based testing. Individuals accepting versus refusing testing differed in perceived COVID-19 risk (67%, 49%; P <0.001), belief in accurate test results (79%, 47%; P <0.001), and ability to test easily (96%, 55%; P <0.001). Males (adjusted odds ratio [aOR]: 1.26 [1.04-1.53]) and those over 50 years (aOR: 1.9 [1.4-2.7]), with symptoms (aOR: 1.80 [1.30-2.50]), and at least partial vaccination (aOR: 0.76 [0.58-0.99]) were significantly associated with test acceptance. Refusal reasons included lack of perceived need for testing (33.8%) and testing discomfort (26.3%). Although community-based testing was generally perceived as important, actual testing uptake was low. In future pandemics, community testing should be optimized by addressing misinformation, offering alternative testing modalities for greater comfort, creating demand, and tailoring approaches to maximize testing uptake.

Community-Based Delivery and Administration of Sars-CoV-2 Antigen Rapid Diagnostic Tests: An Operational Research Study in Marketplaces in Malawi and Zambia.

To expand access to testing beyond public health facilities and to strengthen surveillance efforts for COVID-19, community testing using COVID-19 antigen-based rapid diagnostic tests (Ag-RDTs) was identified as a major area of focus in Malawi and Zambia. This research aimed to gather evidence on the feasibility and acceptability of community testing in marketplaces. A cross-sectional study with a mixed-methods design was conducted in marketplaces in Malawi and Zambia to understand operational considerations for the implementation of Ag-RDTs for SARS-CoV-2 in a community setting. Programmatic data were collected prospectively as individuals were tested from June to September 2022. COVID-19 testing was done using Abbott Panbio nasal swab test kits. Semi-qualitative questionnaires were administered to individuals who tested, healthcare workers, and site-based personnel. Data were collected electronically via the SurveyCTO platform and analyzed using STATA. In Malawi, 2,348 participants were tested, and in Zambia, 1,723 people were tested for COVID-19. In Zambia, participants were 46% female, with a median age of 28 years, whereas in Malawi, participants were 69% female, with a median age of 37 years. In Malawi, 78 positive cases were reported (3.3% positivity rate), and in Zambia 10 positive cases were reported (0.5% positivity rate). In Zambia, 99% of 300 participants and in Malawi, 92% of 1,158 testers found the market testing experience and sample collection acceptable. Community testing is a feasible and acceptable intervention to increase testing access in Malawi and Zambia, especially when coupled with community awareness campaigns and mobilization.

Usefulness of RSV rapid diagnostic tests in hospitalised children

Introduction and objective: Respiratory syncytial virus is a major cause of lower respiratory tract infections, particularly in children under two years of age. Diagnostic methods include rapid antigen diagnostic tests, which have shown high specificity and variable sensitivity. The aims of this study were to verify the performance of these tests in hospitalised children, and to identify factors influencing the results. Materials and methods: The study enrolled children under two years old who were tested for respiratory syncytial virus using both rapid antigen diagnostic test and a cartridge-based nucleic acid amplification test. The sensitivity, specificity, and positive and negative predictive values of the tests were calculated. The influence of symptoms and fever duration, socioeconomic conditions, presence of siblings, and feeding method were analysed. Results: A total of 164 patients aged 10 days to 24 months (median 2.5 months) were included. Sensitivity reached 75% (95% confidence interval: 67.3–81.7%), specificity – 100% (73.5–100%), positive predictive value – 100%, and negative predictive value – 24% (19.3–29.4%). Lower sensitivity was associated with longer duration of signs/symptoms, with the lowest value obtained in the group with 6–7 days of signs/symptoms – 47.4% (24.5–71.1%), which differed from the 2–3 days group (p = 0.005) and the 4–5 days group (p = 0.016). No association was found between sensitivity and patient age, socioeconomic conditions, presence of siblings, clinical course including fever, or feeding method. None of these factors affected specificity, positive or negative predictive value. Conclusions: The reliability of the rapid antigen diagnostic tests in cases of positive results appears to be high, though negative results should be interpreted with caution. Prolonged duration of signs/symptoms before testing might reduce the level of sensitivity.

Development and Diagnosis Performance of IgM-Based Rapid Antigen Test for Early Detection of SARS-CoV-2 Infection in a Large Cohort of Suspected COVID-19 Cases - USA, Poland, and Sweden, 2021-2022.

Antigen testing has been crucial in effectively managing the coronavirus disease 2019 (COVID-19) pandemic. This study evaluated the clinical performance of a nasopharyngeal swab (NPS)-based antigen rapid diagnostic test (Ag-RDT) compared to the gold standard real-time reverse transcription-polymerase chain reaction (RT-PCR) for early detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We developed an IgM-based rapid antigen test for early detection of SARS-CoV-2 infection. Between July 2021 and January 2022, we analyzed 1,030 NPS samples from participants at three centers in different countries, using both antigen rapid diagnostic tests (Ag-RDT) and RT-PCR. The Ag-RDT demonstrated minimal detection limits as low as 0.1 ng/mL for recombinant N antigen and 100 TCID50/mL for heat-inactivated SARS-CoV-2 virus. Specificity assessments involving four human coronaviruses and 13 other respiratory viruses showed no cross-reactivity. The Ag-RDT assay (ALLtest) exhibited high sensitivity (93.18%-100%) and specificity (99.67%-100%) across all centers. Factors such as cycle threshold (Ct) values and the timing of symptoms since onset were influential, with sensitivity increasing at lower Ct values (<30) and within the first week of symptoms. The ALLtest Ag-RDT demonstrated high reliability and significant potential for diagnosing suspected COVID-19 cases.

Assessing the Benefit of Two Detection Approaches in Screening COVID-19 Using SARS-CoV-2 Antigen Rapid Diagnostic Tests among Intercity Public Bus Travelers.

The movement of people contributes to the spread of COVID-19 between communities. Hence, we evaluated the feasibility, acceptability, and impact of offering intercity bus travelers testing prior to their departure. We conducted baseline and endline surveys to map COVID-19 prevention practices in travel agencies in western Cameroon. As interventions, buses were randomly assigned to three study arms: 1) offering systematic COVID-19 rapid diagnostic testing (RDT) to all passengers (arm A); 2) offering testing to suspected cases (arm B); or 3) no testing (arm C). All travelers were called 7-10 days after their trip to identify potential cases. Fifty-five (90.2%) of the 61 travel agencies that were reached consented to participate in a baseline survey. Although only 27 (49.1%) of the agencies implemented at least one of the recommended COVID-19 preventive measures, 39 (70.9%) agreed to host a testing station. Six agencies were selected, and 669 buses were enrolled, including 223, 224, and 222 in arms A, B, and C, respectively. A total of 31,484 departing passengers were approached and 9,594 (30.5%) agreed to participate: 1,177 (12.3%) in arm A, 4,086 (42.6%) in arm B, and 4,331 (45.1%) in arm C. In all, 1,731 tests were performed, including 1,177 in arm A and 554 in arm B. Fourteen (0.8%) tests were positive, and two participants (14.3%) agreed to postpone their travel. Offering testing with antigen RDTs in travel agencies is feasible and acceptable. One-third of passengers consented, and testing did not delay any travels. Although this approach can detect COVID-19 cases, actions are needed to increase the proportion of positive cases postponing their travels.

Use of Antigen Rapid Diagnostic Test for Detection of COVID-19 Cases in University Settings in Cameroon.

Robust testing strategies are an essential aspect of COVID-19 pandemic preparedness and response. In 2022, most regions of Cameroon were still below the WHO's recommended level of 10 COVID-19 tests per 10,000 population. This study aimed to detect SARS-CoV-2 cases in university settings in Cameroon using antigen rapid diagnostic tests (Ag-RDTs) to increase national testing capacity and assess the knowledge, attitudes, and practices of this population regarding COVID-19 infection. Six universities in Buea, Douala, Dschang, Maroua, Ngaoundere, and Yaounde participated in this study from June to October 2022. Nasopharyngeal swabs were collected from participants and tested for COVID-19 using Ag-RDTs. For all positive cases, high-risk contacts were also tested by Ag-RDT. Participants were administered a structured questionnaire to assess their knowledge, attitudes, and practices regarding COVID-19. A total of 7,006 participants were recruited, and 54 (0.8%) were positive for SARS-CoV-2. Among close contacts, three of 62 (4.8%) tested positive. The University of Maroua was the only site to consistently report satisfactory testing capacity, achieving the study target of 30 tests/10,000 in 94.1% of cases. Participants' knowledge of COVID-19 was moderate to good (≥50%). However, 28% were unsure about the effectiveness of the COVID-19 vaccine. Two main factors were identified that could facilitate the spread of SARS-CoV-2 in university settings, namely the lack of restrictions on entering campus without a mask (36%) and the non-respect of social distancing on campus (42.7%). The results of this study will guide future policies to better control diseases with epidemic or pandemic potential by targeting educational institutions.

Clinical Evaluation of the Accuracy of the Panbio™ COVID-19/Flu A&B Rapid Panel: A Combination Antigen Rapid Diagnostic Test for the Omicron Variant and Influenza A Virus.

It is difficult to differentiate between coronavirus disease 2019 (COVID-19) and influenza based on the symptoms. In the present study, a newly developed antigen rapid diagnostic test (Ag-RDT) called Panbio™ COVID-19/Flu A&B that can simultaneously detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza A/B virus was evaluated. Its accuracy was evaluated using 235 pairs of nasopharyngeal samples collected from patients with respiratory symptoms and fever (>37.5°C). Reverse transcription polymerase chain reaction was used as a reference method to evaluate the accuracy of the SARS-CoV-2 detection. We confirmed the accuracy of the developed Ag-RDT against the Omicron variant where the sensitivity and specificity were 94.8% and 100%, respectively. In addition, to identify the influenza A virus, a noninferiority test was conducted using a commercial Ag-RDT, which has a sensitivity and specificity in comparison with viral culture of 94.8% and 98.4%, respectively. The positive and negative predictive values for influenza A virus were 98.5% and 98.1%, respectively, for the Panbio COVID-19/Flu A&B test. The evaluation of this newly developed Ag-RDT using clinical samples suggests that it has a high efficacy in clinical settings.

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.