Rapid Antigen Detection Research Articles

Diagnóstico de onicomicosis. La utilidad del test rápido de detección antigénica en comparación con el cultivo

BackgroundRingworm is highly prevalent in our setting and is frequently observed in our routine clinical practice. Diagnostic confirmation depends on techniques that are not always accessible (PCR), with highly variable sensitivity depending on the observer (direct microscopy) or delayed results (culture, histopathology). Recently, an immunochromatography-based rapid test (Diafactory®) for the antigenic detection of dermatophytes has been developed. This diagnostic tool can help diagnose ringworm, allowing early initiation of treatment and fewer consultation visits. ObjectiveTo determine the sensitivity and specificity of the rapid antigen detection test compared to conventional culture. Material and methodsFor a full year, 333 nail samples were collected from patients with suspected onychomycosis. The rapid test and the conventional culture were simultaneously performed on each sample. Those with a positive antigenic test result began treatment early. The remaining patients had appointments for serial cultures and subsequent medical consultation to evaluate the results. ResultsCompared to conventional culture, the sensitivity and specificity rates of the rapid antigen detection test are 97.2% and 80.7%, respectively. ConclusionThe effectiveness of the rapid antigen detection test is similar to that of conventional culture for the detection of dermatophytes in nail samples. It is a quick and simple diagnostic technique that reduces the number of patient visits to the hospital, and allows early treatment start.

Enhancing the sensitivity of rapid antigen detection test (RADT) of different SARS-COV-2 variants and lineages using fluorescence-labeled antibodies and a fluorescent meter

Enhancing the sensitivity of rapid antigen detection test (RADT) of different SARS-COV-2 variants and lineages using fluorescence-labeled antibodies and a fluorescent meter

METODE DIAGNOSIS INFEKSI TRICHOMONAS VAGINALIS TERKINI

Recent advances in tests for the sexually transmitted protozoan parasite Trichomonas vaginalis have increased opportunities for diagnosis and treatment of this important sexually transmitted infection. This review summarizes current available tests, highlighting their performance characteristics, advantages, and limitations. The recent development of molecular tests for the detection of T vaginalis, including rapid antigen detection and nucleic acid amplification tests, has significantly improved the quality of diagnostics for trichomoniasis, particularly in women. In light of the expanded menu of testing options now available, improved recognition and better control of trichomoniasis are in sight, which should enable the eventual reduction of adverse reproductive consequences associated with T vaginalis infection.

Tonsils at Telethon: developing a standardised collection of tonsil photographs for group A streptococcal (GAS) research.

Group A streptococcus (GAS) infections, such as pharyngitis and impetigo, can lead to rheumatic fever and rheumatic heart disease (RHD). Australian Aboriginal and Torres Strait Islander populations experience high rates of RHD and GAS skin infection, yet rates of GAS pharyngitis are unclear. Anecdotally, clinical presentations of pharyngitis, including tonsillar hypertrophy and sore throat, are uncommon. This study aimed to develop a standardised set of tonsil photographs and determine tonsil size distribution from an urban paediatric population. A prospective cohort of children aged 3-15 years were recruited at the public events "Discover Day" and "Telethon Weekend" (October 2017) in Perth, Western Australia, Australia. Tonsil photographs, symptomatology, and GAS rapid antigen detection tests (RADT) were collected. Tonsil size was graded from the photographs using the Brodsky Grading Scale of tonsillar hypertrophy (Brodsky) by two independent clinicians, and inter-rater reliability calculated. Pharyngitis symptoms and GAS RADT were correlated, and immediate results provided. Four hundred and twenty-six healthy children participated in the study over three days. The median age was seven years [interquartile range (IQR) 5.9-9.7 years]. Tonsil photographs were collected for 92% of participants, of which 62% were rated as good-quality photographs and 79% were deemed of adequate quality for assessment by both clinicians. When scored by two independent clinicians, 57% received the same grade. Average Brodsky grades (between clinicians) were 11%, 35%, 28%, 22% and 5% of grades 0,1,2,3 and 4, respectively. There was moderate agreement in grading using photographs, and minimal to weak agreement for signs of infection. Of 394 participants, 8% reported a sore throat. Of 334 GAS RADT performed, <1% were positive. We report the first standardised use of paediatric tonsil photographs to assess tonsil size in urban-living Australian children. This provides a proof of concept from an urban-living cohort that could be compared with children in other settings with high risk of GAS pharyngitis or rheumatic fever such as remote-living Australian Indigenous populations.

Hydrangea-like TiO2/Bi2MoO6 porous nanoflowers triggering highly sensitive electrochemical immunosensing to tumor marker.

Rapid and sensitive detection of carcinoembryonic antigen (CEA) is of great significance for cancer patients. Here, molybdenum (Mo) was doped into bismuth oxide (Bi2O3) by one-pot hydrothermal method forming porous tremella Bi2MoO6 nanocomposites with a larger specific surface area than the spherical structure. Then, a new kind of hydrangea-like TiO2/Bi2MoO6 porous nanoflowers (NFs) was prepared by doping titanium into Bi2MoO6, where titanium dioxide (TiO2) grew in situ on the surface of Bi2MoO6 nanoparticles (NPs). The hydrangea-like structure provides larger specific surface area, higher electron transfer ability and biocompatibility as well as more active sites conducive to the attachment of anti-carcinoembryonic antigen (anti-CEA) to TiO2/Bi2MoO6 NFs. A novel label-free electrochemical immunosensor was then constructed for the quantitative detection of CEA using TiO2/Bi2MoO6 NFs as sensing platform, showing a good linear relationship with CEA in the concentration range 1.0pg/mL ~ 1.0mg/mL and a detection limit of 0.125pg/mL (S/N = 3). The results achieved with the designed immunosensor are comparable with many existing immunosensors used for the detection of CEA in real samples.

Assessing the Burden of Respiratory Syncytial Virus-related Bronchiolitis in Primary Care and at 15-Day and 6-Month Follow-up Before Prophylaxis in France: A Test-negative Study.

To assess the burden of respiratory syncytial virus (RSV)-related bronchiolitis in primary care and at 15 days and 6 months after a primary care visit. In this test-negative study, children <2 years old with a first episode of bronchiolitis were prospectively enrolled by 45 ambulatory pediatricians in France from February 2021 to April 2023. RSV was assessed with a rapid antigen detection test. The burden of the disease was assessed with a questionnaire, including quality of life (PedsQL 1.0 Infant Scales), at 15-day and 6-month follow-up. Children with a positive RSV test result (RSV+) were compared to those with a negative test result (RSV-). Among the 1591 children enrolled, 750 (47.1%) were RSV+. At 15 days follow-up (data availability: 69%), as compared with RSV- children, RSV+ children more frequently had fever (20.5% vs. 13.7%, P = 0.004) and decreased food intake (27.0% vs. 17.4%, P < 0.001) during the last 3 days. They had higher rates of hospitalization (11.8% vs. 5.8%, P < 0.001), childcare absenteeism (83.5% vs. 66.1%, P < 0.001) and parents who had to stop working to care for them (59.1% vs. 41.0%, P < 0.001) as well as lower quality of life (median PedsQL score 76.2 vs. 78.4, P = 0.03). At 6 months (data availability: 48.5%), the 2 groups did not differ in proportion of medical attendance, hospitalization, antibiotic treatment or quality of life. RSV+ children experienced much more severe disease and follow-up family and societal burden than RSV- children. These data may be used as baseline data as RSV prophylaxis is about to be implemented.

Rapid detection of carcinoembryonic antigen by means of an electrochemical aptasensor

Rapid detection of carcinoembryonic antigen by means of an electrochemical aptasensor

Appropriateness of Use of Streptococcal Pharyngitis Testing and Associated Antibiotic Prescribing in the Urgent Care Setting.

The primary objective was to evaluate Group A streptococcal (GAS) tests performed with a Modified Centor Criteria (MCC) Score < 3 at Urgent Care Clinics (UCC). Secondary objectives included evaluating the MCC sensitivity and specificity, antibiotics prescribed with an MCC score < 3, and association between palatal petechiae and GAS pharyngitis infections. This was a retrospective review from July 1, 2018, to June 30, 2019, of Rapid Antigen Detection Tests (RADTs) on patients with ICD codes associated with pharyngitis. Fifteen hundred patient charts were reviewed. The majority of MCC scores were < 3 at 60.0% (878/1464). Sensitivity of GAS testing (RADT/culture) slightly increased for MCC scores ≥ 3 and was better than the specificity of those scores. In comparison, MCC scores < 3, showed better specificity compared to sensitivity. Over 50% of RADTs performed were inappropriate per clinical guidelines. MCC score < 3 had higher rates of negative test results.

Genetic characterisation of canine adenovirus type 1 in an 18‐month‐old mixed breed male dog and its effect on clinico‐pathology, hemato‐biochemistry and serum oxidant–antioxidant status

AbstractAn 18‐month‐old, mixed breed male dog was presented with hypothermia, recumbency, hematemesis, melena, and moribund condition, and screened by rapid antigen detection kit followed by polymerase chain reaction confirmation for canine adenovirus type 1 infection. The phylogenetic analysis of the sequence revealed clustering with Indian, Spanish, Italian, Portuguese, Chinese, and Australian sequences with amino acid homology of 98.81%–100%. There was a mutation (N127D) in the E3 protein encoding sequence, which was hitherto reported only in one Indian (GQ340423) sequence. Haemogram revealed anaemia, neutropenic leukopenia, and thrombocytopenia. Serum biochemistry revealed marked hyperglycaemia, hypoproteinemia, hypoalbuminemia, and an increase in the activities of hepatic enzymes. Serum oxidant antioxidant parameters revealed a marked increase in the level of oxidant and a decreased level of antioxidants. Postmortem examination revealed multifocal necrotic patches in the liver, marked haemorrhage in the stomach and intestines, emphysematous lungs, splenomegaly, and congested kidney. Histopathology revealed necrohaemorrhagic hepatitis and intranuclear inclusion bodies in the hepatocytes and glomerular degeneration.

Group A Streptococcus pharyngitis in Children: New Perspectives on Rapid Diagnostic Testing and Antimicrobial Stewardship.

The most common cause of bacterial pharyngitis is Group A Streptococcus (GAS). Accurate diagnosis of GAS pharyngitis is crucial to identify children who would benefit from antibiotic treatment. Rapid diagnosis has the potential to reduce antibiotic overuse. Current national guidelines differ in their recommendations for GAS testing. While rapid antigen detection tests (RADTs) are widely used, their sensitivity is considered too low for stand-alone testing by several expert bodies. Newer molecular tests using nucleic acid amplification show higher accuracy and fast results, but their cost, complexity, and very high sensitivity may limit widespread adoption. This review provides up-to-date evidence regarding rapid diagnostic testing and antimicrobial stewardship in children with sore throat. We discuss discrepancies across GAS testing guidelines at the international level, patient selection for testing for GAS, rapid test accuracy, and the potential role of rapid GAS tests to promote antibiotic stewardship, with emphasis on emerging rapid molecular tests.

Antimicrobial Stewardship in Pediatric Emergency Medicine: A Narrative Exploration of Antibiotic Overprescribing, Stewardship Interventions, and Performance Metrics.

Antibiotic overprescribing is prevalent in pediatric emergency medicine, influenced by clinician-caregiver dynamics and diagnostic uncertainties, and poses substantial risks such as increasing antibacterial resistance, adverse drug reactions, and increased healthcare expenditures. While antimicrobial stewardship programs have proven effective in optimizing antibiotic use within inpatient healthcare settings, their implementation in pediatric emergency medicine presents specific challenges. Existing biomarkers like white blood cell count, C-reactive protein, procalcitonin, and presepsin have limitations in their ability to distinguish (serious) bacterial infections from other etiologies of fever. Furthermore, rapid antigen detection tests and guidelines aimed at guiding antibiotic prescriptions for children have not consistently reduced unnecessary antibiotic use. To improve antibiotic prescribing practices, potential strategies include the utilization of decision support tools, audit and feedback, establishing follow-up procedures, implementing safety netting systems, and delivering comprehensive training and supervision. Notably, host genome signatures have also gained attention for their potential to facilitate rapid and precise diagnoses of inflammatory syndromes. Standardized metrics are crucial for evaluating antimicrobial use within pediatric healthcare settings, enabling the establishment of benchmarks for assessing antibiotic utilization, quality enhancement initiatives, and research endeavors.

AIEgens-enhanced rapid sensitive immunofluorescent assay for SARS-CoV-2 with digital microfluidics

BackgroundSensitive and rapid antigen detection is critical for the diagnosis and treatment of infectious diseases, but conventional ELISAs including chemiluminescence-based assays are limited in sensitivity and require many operation steps. Fluorescence immunoassays are fast and convenient but often show limited sensitivity and dynamic range. ResultsTo address the need, an aggregation-induced emission fluorgens (AIEgens) enhanced immunofluorescent assay with beads-based quantification on the digital microfluidic (DMF) platform was developed. Portable DMF devices and chips with small electrodes were fabricated, capable of manipulating droplets within 100 nL and boosting the reaction efficiency. AIEgen nanoparticles (NPs) with high fluorescence and photostability were synthesized to enhance the test sensitivity and detection range. The integration of AIEgen probes, transparent DMF chip design, and the large magnetic beads (10 μm) as capture agents enabled rapid and direct image-taking and signal calculation of the test result. The performance of this platform was demonstrated by point-of-care quantification of SARS-CoV-2 nucleocapsid (N) protein. Within 25 min, a limit of detection of 5.08 pg mL−1 and a limit of quantification of 8.91 pg mL−1 can be achieved using <1 μL sample. The system showed high reproducibility across the wide dynamic range (10–105 pg mL−1), with the coefficient of variance ranging from 2.6% to 9.8%. SignificanceThis rapid, sensitive AIEgens-enhanced immunofluorescent assay on the DMF platform showed simplified reaction steps and improved performance, providing insight into the small-volume point-of-care testing of different biomarkers in research and clinical applications.

Comparative study between gold standard real-time RT-PCR assay and rapid antigen test for detection of COVID-19 in Sylhet CMH

Background: The notorious pandemic coronavirus disease 2019 (COVID-19) has been spread all over the world. Its third pandemic wave has been completed and now a fourth wave is running over many countries. Almost 60 million people have been infected and more than 5.7 million people have died. Till now almost 1.2 million people have been infected and about 30000 people have died in Bangladesh from Covid-19. It has not only taken away human lives but also has put a tremendous impact on our society and economy. So early detection of this virus and isolating the patients have a significant role to control the disease. Henceforth there is an urgent need for simple, accurate and rapid identifications of C0VID -19. Rapid antigen tests can provide timely results, which is of particular importance in a primary setting. So, Performance of the Rapid antigen detection test (RAT) should be evaluated and compared with gold standard real-time reverse transcription-polymerase chain reaction (RT-PCR) test for diagnosis of COVID-19. Methods: Specimens were collected from both naso and oropharyngeal region from 1000 patients who reported to the flu centre in CMH Sylhet with the complaints of fever, cough &amp; headache for detection of COVID virus-2 RNA by rapid antigen (RAT) and RT-PCR test. We used real time RT-PCR kit (Sansure, Biotech china, gene RdRP &amp; N) and COVID-19 Ag Kit (Wondfo, Republic of China) for detection of COVID-19 RNA. Results: Out of 1000 samples 158 were positive and 842 were negative by real-time RT-PCR assay where 154 samples were positive, and 846 cases were negative by rapid antigen test for severe acute respiratory syndrome (SARS) CoV-2. The duration from the onset of symptoms to laboratory test in all suspected cases ranged from 0 to 02 days (with a median of 01 days). The rapid SARS-CoV-2 antigen detection tests sensitivity and specificity were 97.29% (95% CI, 90.06–99.89%) and 97.94% (95% CI, 97.26–98.57%), respectively. Seven samples were found negative in RAT but were found positive in RT-PCR, other three samples were found positive in RAT while they were found negative in RT-PCR. Conclusions: It is observed that most rapid antigen tests for COVID-19 are significantly comparable with RT-PCR tests and had enough sensitivity and specificity for 158 individuals, infected with severe acute respiratory syndrome-CoV-2.

Point-of-care testing and antibiotics prescribing in out-of-hours general practice: a register-based study in Denmark

BackgroundPoint-of-care testing may reduce diagnostic uncertainty in case of suspicion of bacterial infection, thereby contributing to prudent antibiotic prescribing. We aimed to study variations in the use of point-of-care tests (C-reactive protein test, rapid streptococcal antigen detection test, and urine dipstick) among general practitioners (GPs) and the potential association between point-of-care testing and antibiotic prescribing in out-of-hours general practice.MethodsWe conducted a population-based observational register-based study, based on patient contacts with out-of-hours general practice in the Central Denmark Region in 2014–2017. The tendency of GPs to use point-of-care testing was calculated, and the association between the use of point-of-care testing and antibiotic prescribing was evaluated with the use of binomial regression.ResultsOut-of-hours general practice conducted 794,220 clinic consultations from 2014 to 2017, of which 16.1% resulted in an antibiotic prescription. The GP variation in the use of point-of-care testing was largest for C-reactive protein tests, with an observed variation (p90/p10 ratio) of 3.0; this means that the GPs in the 90th percentile used C-reactive protein tests three times as often as the GPs in the 10th percentile. The observed variation was 2.1 for rapid streptococcal antigen detection tests and 1.9 for urine dipsticks. The GPs who tended to use more point-of-care tests prescribed significantly more antibiotics than the GPs who tended to use fewer point-of-care tests. The GPs in the upper quintile of the tendency to use C-reactive protein test prescribed 22% more antibiotics than the GPs in the lowest quintile (21% for rapid streptococcal antigen detection tests and 8% for urine dipsticks). Up through the quintiles, this effect exhibited a positive linear dose–response correlation.ConclusionThe GPs varied in use of point-of-care testing. The GPs who tended to perform more point-of-care testing prescribed more antibiotics compared with the GPs who tended to perform fewer of these tests.

Diagnosis of COVID-19 obtained by rapid antigen test and reverse transcription–polymerase chain reaction in a medical college in Eastern India-a record-based observational descriptive study

Background: In December 2019 in Wuhan, China, a new coronavirus known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) appeared. Gradually, the virus started spreading around the world, which was life-threatening. Aims and Objectives: The study’s objective was to find out the positivity rate of infection, the category of patients included in the study, the percentage of positive and negative cases, comparison of rapid antigen detection in relation to real-time reverse transcription–polymerase chain reaction (RT-PCR) test, and rapid antigen detection test’s sensitivity and specificity. Materials and Methods: Eight hundred sixty-five patients’ samples and nasopharyngeal swabs were collected within 3 months as routine samples. Two hundred thirty-two samples were compared by both rapid antigen test (RAT) and RT-PCR. To rule out false negatives, those who tested negative for COVID-19 using a RAT underwent testing by RT-PCR. To rule out false positives, a small number of patients who tested positive for COVID-19 by RAT also underwent validation by RT-PCR test. Results: Two hundred thirty-two samples were obtained for rapid antigen detection, then RT-PCR testing. Both the results were compared. According to the findings, the positivity rate of COVID-19 infection was 0.86%. Two patients (0.86%) tested positive (either by one or both methods) and the number of patients who tested negative was 230 (99.14%). RAT sensitivity and specificity were 50% and 100%, respectively, compared to gold standard RT-PCR. The positive predictive value was 100% and the negative predictive value was 99%. Conclusion: We conclude that antigen detection methods are less sensitive than real-time RT-PCR but they can be used for COVID-19 mass screening and can be used as a quick diagnostic tool in remote locations without molecular testing facilities.

Development and characterization of a lateral flow immunochromatographic assay test strip for rapid detection of rubella virus antigen

Rubella is still considered a dangerous infectious disease, especially for pregnant women. The symptoms of rubella can be similar to those of other illnesses. Therefore, an early and accurate diagnosis of the rubella virus will help doctors make a reasonable treatment plan. This study presents the development and characterization of a novel lateral flow immunochromatographic assay test strip for rapid recognition of rubella virus antigen. Rabbit polyclonal antibodies against the rubella virus were purified with a purity of 95%. Optimal conditions for the production of the main components of a test strip were determined. Anti-rubella virus polyclonal antibodies were physically adsorbed onto the star-shaped gold nanoparticles at the optimal concentration of 1.0 μg/ml at 25°C for 30 min. The amounts of antibody per conjugate pad and immobilized on the test line were 0.2 μg/pad and 4.5 μg/cm, respectively. The properties of the test strip were characterized by testing mock clinical specimens. Reproducibility and repeatability were achieved at 100%. The limit of detection of the test strip was determined to be as low as 5 × 105 virus particles/mL. The test strip did not cross-react with six different potential interfering pathogens. The sensitivity and specificity of the test strip were determined by testing with 400 mock clinical samples and reached 99.5% and 98.5%, respectively. The Kappa statistics (k coefficient = 0.98) showed very good agreement between the generated test strip and real-time PCR results. According to the findings, the test strip can be used as an additional rapid test tool for the detection of the rubella virus.

Performance of two SARS-CoV-2 rapid antigen detection tests in resource limited settings, the case of Mali.

While real-time reverse transcription PCR (RT-PCR) is the recommended laboratory method to diagnose severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) infection, its use in resource limited settings can be difficult to maintain due to high testing demand and shortage of reagents. The aim of this study was to evaluate the performances of Realy Tech™ and Standard Q™ in comparison to RT-PCR in a relatively low COVID-19 prevalence setting, Mali. We conducted a cross-sectional study between January and April 2021 in Bamako and Kati regions to evaluate both rapid tests during a large SARS-CoV-2 prevalence study in Mali. Of the 390 samples tested, the sensitivity and specificity of Realy Tech™ and Standard Q™ were 57.1% (95%CI: 44.1-69.2), 95.8% (95%CI: 93.1-97.5); 61.9% (95%CI: 46.8-75.0), and 94.1% (95%CI: 89.5-96.8) respectively. Using RT-PCR, the global prevalence of SARS-CoV-2 was 14.4% (56/390). In both rapid antigen tests, the performance was better when used in suspected patients compared to positive patients under treatment. Moreover, higher viral loads equivalent to Ct < 25 were associated with better detection rates. While waiting for more complete data, these preliminary studies suggest that Realy Tech™ and Standard Q™ should not be used alone for COVID-19 diagnosis in Mali.

Ensuring diagnostic testing accuracy for patient care and public health- COVID-19 testing scale-up from an EQA provider's perspective.

In response to the coronavirus pandemic (COVID-19) and scale up of diagnostic testing, the Canadian Microbiology Proficiency Testing program created a new proficiency testing (PT) program for the molecular and antigen detection of SARS-CoV-2. The program was geared to point of care testing (POCT) sites located in each of the eight provincial Health Authorities across British Columbia, Canada, with the intention to monitor testing quality. The PT program consisted of 6 shipments in a year, each containing a set of 4 samples either positive for SARS-CoV-2 virus or negative. The program began with initial 23 sites enrolling in March 2021, expanding to >100 participants by December 2021. After the first two surveys, it was observed that testing performance (accuracy) was consistently acceptable for sites using nucleic acid technology (NAT), however performance by sites using rapid antigen detection (RAD) methods was poor, especially when testing the weakly positive samples. A root cause investigation of poor testing performance revealed gaps in the execution of testing methods and also in results interpretation. These quality issues were most commonly associated with new testers who lacked experience with diagnostic testing. Tester training and mentoring was reinforced as was retraining of personnel; sample processing instructions were modified, and a training video was also created for testing sites. As a result of these interventions, sites improved their testing accuracy and the performance of POCT sites using RAD methods came to more closely match the performance of sites utilizing NAT. Overall, the PT program was highly successfully and improved quality of testing in the province. This work demonstrates the critical value of an external quality assessment (EQA) partner towards improving patient and public health and safety, especially when testing is conducted outside of an accredited medical laboratory setting.

A single-center experience on long-term clinical performance of a rapid SARS-CoV-2 Antigen Detection Test, STANDARD Q COVID-19 Ag Test

The COVID-19 pandemic in Korea has dynamically changed with the occurrence of more easily transmissible variants. A rapid and reliable diagnostic tool for detection of SARS-CoV-2 is needed. While RT-PCR is currently the gold standard for detecting SARS-CoV-2, the procedure is time-consuming and requires expert technicians. The rapid antigen detection test (RADT) was approved as a confirmatory test on 14 March 2022 due to rapid dissemination of the Omicron variant. The benefits of the RADT are speed, simplicity, and point-of-care feasibility. The aim of our study was to evaluate the clinical performance of RADT compared to RT-PCR in a single center over 15 months, fully covering the SARS-CoV-2 ‘Variants of Concern (VOC).’ A total of 14,194 cases was simultaneously tested by RT-PCR and RADT from January 2021 to March 2022 in Gangnam Severance Hospital and were retrospectively reviewed. PowerChek SARS-CoV-2, Influenza A&B Multiplex Real-time PCR Kit, and STANDARD Q COVID-19 Ag Test were used. Positive rates, sensitivities, specificities, positive predictive values (PPV), and negative predictive values (NPV) were estimated for five periods (3 months/period). Receiver operator characteristic curve (ROC) analysis was performed, and Spearman’s rank test assessed the correlation between RT-PCR Ct values and semi-quantitative RADT results. The overall positive rate of RT-PCR was 4.64%. The overall sensitivity and specificity were 0.577 [95% confidence interval (CI) 0.539–0.614] and 0.991 [95% CI 0.989–0.993], respectively. ROC analysis resulted in an area under the curve of 0.786 (P < 0.0001, Yuden’s index = 0.568). The PCR positive rates were estimated as 0.11%, 0.71%, 4.51%, 2.02%, and 13.72%, and PPV was estimated as 0.045, 0.421, 0.951, 0.720, and 0.798 in Periods 1, 2, 3, 4, and 5, respectively. A significant and moderate negative correlation between PCR Ct values and semi-quantitative RADT results was observed (Spearman’s ρ = − 0.646, P < 0.0001). The RADT exhibited good performance in specimens with low Ct values (Ct ≤ 25.00) by RT-PCR. The PPV was significantly higher in Periods 3 and 5, which corresponds to rapid dissemination of the Delta and Omicron variants. The high PPV implies that individuals with a positive RADT result are very likely infected with SARS-CoV-2 and would require prompt quarantine rather than additional RT-PCR testing. The sensitivity of 0.577 indicates that RADT should not replace RT-PCR. Nonetheless, given the high PPV and the ability to track infected persons through rapid results, our findings suggest that RADT could play a significant role in control strategies for further SARS-CoV-2 variants.

2632. Duration of viable SARS-CoV-2 shedding in immunocompromised COVID-19 patients during the widespread vaccination era

Abstract Background Individuals with COVID-19 who are immunocompromised have been reported to experience prolonged shedding of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) compared to those who are immunocompetent. However, it remains unclear how long viable SARS-CoV-2 shedding persists in immunocompromised individuals during the era of widespread vaccination against COVID-19. This study aimed to evaluate the association between the duration of viable SARS-CoV-2 detection among immunocompromised individuals and their COVID-19 vaccination status. Methods We retrospectively reviewed patients who admitted to our institute for COVID-19 treatment between November 2022 and March 2023. We defined immunocompromised individuals as those who had received corticosteroids, immunosuppressants, or cytotoxic chemotherapy. We performed daily COVID-19 rapid antigen detection tests (RAD) on immunocompromised patients from 10 days after the onset of COVID-19 until two consecutive negative results were obtained. Results Among 181 patients admitted for COVID-19 treatment, 22 immunocompromised patients participated in this study. Of these, 14 (64%), 6 (27%), and 10 (46%) patients received corticosteroids, immunosuppressants, and cytotoxic chemotherapy, respectively. Twelve (55%) patients were fully vaccinated. Nine (41%) patients required oxygen therapy for respiratory failure. All patients received antiviral therapy, with 5 (23%), 12 (55%), 5 (23%) patients receiving remdesivir, ritonavir-boosted nirmatrelvir, and molnupiravir, respectively. Three (14%) patients died from COVID-19. The median duration from COVID-19 onset to confirmation of negative RAD or death was 15.5 (interquartile range: 12 to 17) days. Until 20 days after the onset of COVID-19, 17 (77%) patients had achieved two consecutive negative RAD results. There was no association between vaccination status and the duration of positive RAD results (p = 0.59) or the proportion of patients achieving negative RAD results within 20 days of COVID-19 onset (P &amp;gt; 0.99). Conclusion Most immunocompromised COVID-19 patients in our hospital achieved two consecutive negative RAD results within 20 days of COVID-19 onset. Vaccination status was not associated with the duration of detectable SARS-CoV-2 shedding. Disclosures All Authors: No reported disclosures