Quidel Sofia Research Articles

A-267 Evaluation of the Quidel Sofia 2 Rapid Lyme Test in a Modified Two-tier Testing Protocol

Abstract Background Several Modified two-tier testing algorithms (MTTT) for Lyme disease involving sequential enzyme immunoassays (EIA) have been approved by the FDA as an alternative to conventional two-tiered testing using EIA followed by immunoblot. The MTTT algorithms are reported to be more sensitive than conventional two-tiered algorithm’s especially in early Lyme disease. The Quidel Sofia 2 Lyme assay utilizes lateral flow with fluorescence detection (FIA) providing a rapid on-demand instrument-read alternative to central laboratory batch mode testing We compared the Quidel assay as a first-tier test in an MTTT algorithm to the Zeus Scientific VlsE1/pepC10 IgG/IgM enzyme immunoassay (EIA) followed by the Zeus monovalent IgM and IgG EIA as the confirmatory test. Methods Serum specimens (n = 179) were obtained from consecutive samples sent to our clinical laboratory for Lyme serology testing. For the first-tier the samples were tested using the Zeus EIA VlsE1/pepC10 lgG/IgM test and the Quidel Sofia 2 Lyme FIA assay. Positive or equivocal first-tier tests were then tested using the Zeus monovalent IgM and IgG EIA as the confirmatory test. Results The positive percent agreement was 100%, the negative percent agreement 97.9 % with an overall agreement of 98.3%. The Kappa statistic was 0.945 (95% confidence interval 0.883–1.000 indicating “almost perfect” agreement). Conclusion The Quidel Sofia Lyme test performs well when compared to the Zeus test in a two-tiered testing MTTT algorithm. Obtaining samples to evaluate Lyme serologic tests can be challenging. Our data should prove useful for facilities considering the use of the Quidel assay.

Evaluation of the rapid Quidel Sofia Lyme fluorescent immunoassay as a first-tier test in a modified 2-tier testing algorithm for Lyme disease: A comparison with the Zeus ELISA Borrelia VlsE1/pepC10 lgG/IgM assay followed by the Zeus monovalent IgM/IgG confirmatory assay.

Recently modified 2-tier testing (MTTT) algorithms using 2 enzyme immunoassays (EIAs) as opposed to an EIA followed by immunoblot have been approved by the US Food and Drug Administration (FDA) for the screening and confirmation of Lyme disease. The Quidel Sofia Lyme fluorescent immunoassay is a rapid lateral-flow method that can be performed in real time, permitting on-demand testing. We evaluated the performance of the Sofia assay as a first-tier test in an MTTT algorithm. We compared the Sofia Lyme test with the Zeus ELISA Borrelia VlsE1/pepC10 lgG/IgM test, followed by the Zeus monovalent IgM/IgG EIA as the confirmatory test. When used as a first-tier test compared with a standard Zeus MTTT assay, the positive percentage agreement was 91.4%% (95% CI, 77.6%-97.0%). The negative percentage agreement was 100% (95% CI, 94.0%-100%). The overall agreement was 98.3% (95% CI, 94.2%-99.4%). κ = 0.945, indicating "almost perfect agreement." The Sofia Lyme test performs well compared with an FDA-approved MTTT.

Evaluation of the Rapid Quidel Sofia 2 Lyme Immunoassay as a First-Tier Test in a Two-Tier Testing Algorithm for Lyme Disease: Comparison to the Zeus ELISA Borrelia VlsE1/pepC10 IgG/IgM Assay Followed by Immunoblot.

Two-tiered serologic testing for Lyme disease is usually performed using an enzyme-linked immunosorbent assay (ELISA) as the first-tier test. The Quidel Sofia 2 Lyme test is a relatively new lateral flow method to provide more rapid turnaround time. We evaluated its performance in comparison to an established ELISA method. The test can be performed on demand rather than batching assays in a central laboratory. We compared the Sofia 2 assay to the Zeus VlsE1/pepC10 IgG/IgM test in a standard two-tiered testing algorithm. Comparison of the Sofia 2 to the Zeus VlsE1/pepC10 IgG/IgM showed an overall agreement of 89.9% (κ statistic of 0.750, indicating "substantial agreement"). When the tests were followed by immunoblot in a two-tier algorithm, the agreement was 98.9% (κ statistic of 0.973, indicating "almost perfect" agreement). The Sofia 2 Lyme test performs well when compared with the Zeus VlsE1/pepC10 IgG/IgM in a two-tiered testing algorithm.

Performance of the Sofia SARS-CoV-2 Rapid Antigen Test in Symptomatic and Asymptomatic Pediatric Patients.

The sensitivity and specificity of SARS-CoV-2 antigen tests have not been widely assessed in children. We evaluated children presenting to outpatient care with Quidel Sofia SARS-CoV-2 antigen test (Sofia-Ag-RDT) compared against Cepheid Xpert Xpress SARS-CoV-2/Flu/RSV reverse transcriptase-polymerase chain reaction test from November 2020 to April 2021. Sofia-Ag-RDT had the highest sensitivity in symptomatic (82%; 95% confidence interval, 68%-91%) children.

Predicting Direct-Specimen SARS-CoV-2 Assay Performance Using Residual Patient Samples.

BackgroundDiagnostic sensitivities of point-of-care SARS-CoV-2 assays depend on specimen type and population-specific viral loads. Evaluation of these assays require ‘direct’ specimens from paired-swab studies rather than more accessible residual specimens in viral transport media (VTM).MethodsResidual VTM and limit-of-detection studies were conducted on Abbott ID NOW™ COVID-19, Quidel Sofia 2™ SARS Antigen FIA, and DiaSorin Simplexa™ COVID-19 Direct assays, with cycle threshold (CT) adjustments to approximate direct-specimen testing based on gene-target doubling each PCR cycle. Logistic regression was used to model assay performance by specimen CT. These models were applied to CT distributions of symptomatic and asymptomatic populations presenting to emergency services to predict the percent of specimens that would be detected by each assay. A 96-sample paired-swab study was conducted to confirm model results.ResultsWhen using direct nasopharyngeal samples and fit with either VTM or limit-of-detection data, percent positivities for ID NOW (symptomatic 94.9%/97.4%; asymptomatic 88.4.0%/89.6%) and Simplexa (symptomatic 97.8%/97.2%; asymptomatic 91.1%/90.8%) were predicted to be similar. Likewise, fit with VTM data, percent positivities for ID NOW with direct nasal specimens (symptomatic 77.8%; asymptomatic 64.5%) and Sofia 2 with direct nasopharyngeal specimens (symptomatic 76.6%, asymptomatic 60.3%) were similar. The paired-swab study comparing direct nasopharyngeal specimens on ID NOW and nasopharyngeal VTM specimens on Simplexa showed 99% concordance.ConclusionsAssay performance can be modeled as dependent on viral load, fit using laboratory bench study results, and adjusted to account for direct-specimen testing. When using nasopharyngeal specimens, direct testing on Abbott ID NOW and VTM testing on DiaSorin Simplexa have similar performance.

Comparison of SARS-CoV-2 Antigen Tests in Asymptomatic Testing of Passengers at German Airports under Time Constraints: Application of Three Different Antigen Test Formats

People infected asymptomatically with SARS-CoV-2 can spread the virus very efficiently. To break infection chains, massive testing efforts are underway. While the value of RT-PCR in asymptomatic patients is established, point-of-care (POC) antigen tests against SARS-CoV-2 are considered inferior to RT-PCR in terms of sensitivity and specificity but have demonstrated utility, mostly in symptomatic patients. We compared the performance of three different antigen tests with colorimetric (Roche), fluorometric (Quidel Sofia 2), and instrument-based chemiluminescent (Fujirebio Lumipulse® G) readout. Sensitivities for Roche, Quidel, and Fujirebio were 62.5%, 90.9%, 97.5% (≤ct 26); 43.8%, 90.9%, 95.1% (≤ct 30); and 4.3%, 0.0%, 57.6% (˃ct 30), respectively. The two assays with increased sensitivity were employed to screen > 35,000 passengers at German airports under time constraints. Under real-world conditions, the rate of false positives was low: 0.15% (Quidel) and 0.06% for the instrument based Fujirebio assay. Our study exemplifies that antigen tests with enhanced detection methods have an acceptable sensitivity of >90% in samples containing SARS-CoV-2 RNA that are considered to be infectious. Therefore, our results support the view of the WHO that discourages the use of antigen assays with a sensitivity of “only” 80% for screening travelers.

Performance of SARS-CoV-2 antigen testing in symptomatic and asymptomatic adults: a single-center evaluation

BackgroundAntigen testing offers rapid and inexpensive testing for SARS-CoV-2 but concerns regarding performance, especially sensitivity, remain. Limited data exists for use of antigen testing in asymptomatic patients; thus, performance and reliability of antigen testing remains unclear.Methods148 symptomatic and 144 asymptomatic adults were included. A nasal swab was collected for testing by Quidel Sofia SARS IFA (Sofia) as point of care. A nasopharyngeal swab was also collected and transported to the laboratory for testing by Cepheid Xpert Xpress SARS-CoV-2/Flu/RSV RT-PCR (Cepheid).ResultsOverall, Sofia had good agreement with Cepheid (> 95%) in adults, however was less sensitive. Sofia had a sensitivity of 87.8% and 33.3% for symptomatic and asymptomatic patients, respectively. Among symptomatic patients, testing > 5 days post symptom onset resulted in lower sensitivity (82%) when compared with testing within 5 days of symptom onset (90%). Of the four Sofia false-negative results in the asymptomatic cohort, 50% went on to develop COVID-19 disease within 5 days of testing. Specificity in both symptomatic and asymptomatic cohorts was 100%.ConclusionsSofia has acceptable performance in symptomatic adults when tested < 5 days of symptom onset. Caution should be taken when testing patients with ≥ 5 days of symptoms. The combination of low prevalence and reduced sensitivity results in relatively poor performance of in asymptomatic patients. NAAT-based diagnostic assays should be considered in when antigen testing is unreliable, particularly in symptomatic patients with > 5 days of symptom onset and asymptomatic patients.

Use, Safety Assessment, and Implementation of Two Point-of-Care Tests for COVID-19 Testing.

ObjectivesThe Abbot ID NOW COVID-19 assay and Quidel Sofia 2 SARS Antigen FIA are point-of-care assays that offer rapid testing for severe acute respiratory syndrome coronavirus 2 viral RNA and nucleocapsid protein, respectively. Given the utility of these devices in the field, we investigated the feasibility and safety of using the ID NOW and Sofia assays in the public health response to the coronavirus disease 2019 pandemic and in future public health emergencies.MethodsA combination of utilization and contamination testing in addition to a review of instrument workflows was conducted.ResultsUtilization testing demonstrated that both tests are intuitive, associated with high user test success (85%) in our study, and could be implemented by staff after minimal training. Contamination tests revealed potential biosafety concerns due to the open design of the ID NOW instrument and the transfer mechanisms with the Sofia. When comparing the workflow of the ID NOW and the Sofia, we found that the ID NOW was more user-friendly and that the transfer technology reduces the chance of contamination.ConclusionsThe ID NOW, Sofia, and other emerging point-of-care tests should be used only after careful consideration of testing workflow, biosafety risk mitigations, and appropriate staff training.

A SARS-CoV-2 Nucleocapsid Variant that Affects Antigen Test Performance.

More than one year into a global pandemic, SARS-CoV-2 is now defined by a variety of rapidly evolving variant lineages. Several FDA authorized molecular diagnostic tests have been impacted by viral variation, while no reports of viral variation affecting antigen test performance have occurred to date. While determining the analytical sensitivity of the Quidel Sofia SARS Antigen FIA test (Sofia 2), we uncovered a high viral load specimen that repeatedly tested negative by this antigen test. Whole genome sequencing of the specimen uncovered two mutations, T205I and D399N, present in the nucleocapsid protein of the isolate. All six SARS-CoV-2 positive clinical specimens available in our laboratory with a D399N nucleocapsid mutation and CT < 31 were not detected by the Sofia 2 but detected by the Abbott BinaxNOW COVID-19 Ag Card, while clinical specimens with the T205I mutation were detected by both assays. Testing of recombinant SARS-CoV-2 nucleocapsid with these variants demonstrated an approximate 1000-fold loss in sensitivity for the Quidel Sofia SARS Antigen FIA test associated with the D399N mutation, while the BinaxNOW and Quidel Quickvue SARS Antigen tests were unaffected by the mutation. The D399N nucleocapsid mutation has been relatively uncommon to date, appearing in only 0.02% of genomes worldwide at time of writing. Our results demonstrate how routine pathogen genomics can be integrated into the clinical microbiology laboratory to investigate diagnostic edge cases, as well as the importance of profiling antigenic diversity outside of the spike protein for SARS-CoV-2 diagnostics.

Optimizing SARS-CoV-2 Surveillance in the United States: Insights From the National Football League Occupational Health Program.

Evidence to understand effective strategies for surveillance and early detection of SARS-CoV-2 is limited. To describe the results of a rigorous, large-scale COVID-19 testing and monitoring program. The U.S. National Football League (NFL) and the NFL Players Association (NFLPA) instituted a large-scale COVID-19 monitoring program involving daily testing using 2 reverse transcription polymerase chain reaction (RT-PCR) platforms (Roche cobas and Thermo Fisher QuantStudio), a transcription-mediated amplification platform (Hologic Panther), and an antigen point-of-care (aPOC) test (Quidel Sofia). 32 NFL clubs in 24 states during the 2020 NFL season. NFL players and staff. SARS-CoV-2 test results were described in the context of medically adjudicated status. Cycle threshold (Ct) values are reported when available. A total of 632370 tests administered across 11668 persons identified 270 (2.4%) COVID-19 cases from 1 August to 14 November 2020. Positive predictive values ranged from 73.0% to 82.0% across the RT-PCR platforms. High Ct values (33 to 37) often indicated early infection. For the first positive result, the median Ct value was 32.77 (interquartile range, 30.02 to 34.72) and 22% of Ct values were above 35. Among adjudicated COVID-19 cases tested with aPOC, 42.3% had a negative result. Positive concordance between aPOC test result and adjudicated case status increased as viral load increased. Platforms varied by laboratory, and test variability may reflect procedural differences. Routine RT-PCR testing allowed early detection of infection. Cycle threshold values provided a useful guidepost for understanding results, with high values often indicating early infection. Antigen POC testing was unable to reliably rule out COVID-19 early in infection. The NFL and the NFLPA.

Diagnostic Performance of an Antigen Test with RT-PCR for the Detection of SARS-CoV-2 in a Hospital Setting - Los Angeles County, California, June-August 2020.

Prompt and accurate detection of SARS-CoV-2, the virus that causes COVID-19, has been important during public health responses for containing the spread of COVID-19, including in hospital settings (1-3). In vitro diagnostic nucleic acid amplification tests (NAAT), such as real-time reverse transcription-polymerase chain reaction (RT-PCR) can be expensive, have relatively long turnaround times, and require experienced laboratory personnel.* Antigen detection tests can be rapidly and more easily performed and are less expensive. The performance† of antigen detection tests, compared with that of NAATs, is an area of interest for the rapid diagnosis of SARS-CoV-2 infection. The Quidel Sofia 2 SARS Antigen Fluorescent Immunoassay (FIA) (Quidel Corporation) received Food and Drug Administration Emergency Use Authorization for use in symptomatic patients within 5 days of symptom onset (4). The reported test positive percentage agreement§ between this test and an RT-PCR test result is 96.7% (95% confidence interval [CI]=83.3%-99.4%), and the negative percentage agreement is 100.0% (95% CI=97.9%-100.0%) in symptomatic patients.¶ However, performance in asymptomatic persons in a university setting has shown lower sensitivity (5); assessment of performance in a clinical setting is ongoing. Data collected during June 30-August 31, 2020, were analyzed to compare antigen test performance with that of RT-PCR in a hospital setting. Among 1,732 paired samples from asymptomatic patients, the antigen test sensitivity was 60.5%, and specificity was 99.5% when compared with RT-PCR. Among 307 symptomatic persons, sensitivity and specificity were 72.1% and 98.7%, respectively. Health care providers must remain aware of the lower sensitivity of this test among asymptomatic and symptomatic persons and consider confirmatory NAAT testing in high-prevalence settings because a false-negative result might lead to failures in infection control and prevention practices and cause delays in diagnosis, isolation, and treatment.

Diagnostic Accuracy of the Quidel Sofia Rapid Influenza Fluorescent Immunoassay in Patients with Influenza-like Illness: A Systematic Review and Meta-analysis.

BackgroundAlthough the Quidel Sofia rapid influenza fluorescent immunoassay (FIA) is widely used to identify influenza A and B, the diagnostic accuracy of this test remains unclear. Thus, the objective of this study was to determine the diagnostic performance of this test compared to reverse transcriptase-polymerase chain reaction.MethodsA systematic literature search was performed using MEDLINE, EMBASE, and the Cochrane Central Register. Pooled sensitivity, specificity, diagnostic odds ratio (DOR), and a hierarchical summary receiver-operating characteristic curve (HSROC) of this test for identifying influenza A and B were determined using meta-analysis. A sensitivity subgroup analysis was performed to identify potential sources of heterogeneity within selected studies.ResultsWe identified 17 studies involving 8,334 patients. Pooled sensitivity, specificity, and DOR of the Quidel Sofia rapid influenza FIA for identifying influenza A were 0.78 (95% confidence interval [CI], 0.71–0.83), 0.99 (95% CI, 0.98–0.99), and 251.26 (95% CI, 139.39–452.89), respectively. Pooled sensitivity, specificity, and DOR of this test for identifying influenza B were 0.72 (95% CI, 0.60–0.82), 0.98 (95% CI, 0.96–0.99), and 140.20 (95% CI, 55.92–351.54), respectively. The area under the HSROC for this test for identifying influenza A was similar to that for identifying influenza B. Age was considered a probable source of heterogeneity.ConclusionPooled sensitivities of the Quidel Sofia rapid influenza FIA for identifying influenza A and B did not quite meet the target level (≥80%). Thus, caution is needed when interpreting data of this study due to substantial between-study heterogeneity.

Epidemiologic Characteristics Associated With Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Antigen-Based Test Results, Real-Time Reverse Transcription Polymerase Chain Reaction (rRT-PCR) Cycle Threshold Values, Subgenomic RNA, and Viral Culture Results From University Testing.

BackgroundReal-time reverse transcription polymerase chain reaction (rRT-PCR) and antigen tests are important diagnostics for SARS-CoV-2. Sensitivity of antigen tests has been shown to be lower than that of rRT-PCR; however, data to evaluate epidemiologic characteristics that affect test performance are limited.MethodsPaired mid-turbinate nasal swabs were collected from university students and staff and tested for SARS-CoV-2 using both Quidel Sofia SARS Antigen Fluorescent Immunoassay (FIA) and rRT-PCR assay. Specimens positive by either rRT-PCR or antigen FIA were placed in viral culture and tested for subgenomic RNA (sgRNA). Logistic regression models were used to evaluate characteristics associated with antigen results, rRT-PCR cycle threshold (Ct) values, sgRNA, and viral culture.ResultsAntigen FIA sensitivity was 78.9% and 43.8% among symptomatic and asymptomatic participants respectively. Among rRT-PCR positive participants, negative antigen results were more likely among asymptomatic participants (OR 4.6, CI:1.3-15.4) and less likely among participants reporting nasal congestion (OR 0.1, CI:0.03-0.8). rRT-PCR-positive specimens with higher Ct values (OR 0.5, CI:0.4-0.8) were less likely, and specimens positive for sgRNA (OR 10.2, CI:1.6-65.0) more likely, to yield positive virus isolation. Antigen testing was >90% positive in specimens with Ct values <29. Positive predictive value of antigen test for positive viral culture (57.7%) was similar to that of rRT-PCR (59.3%).ConclusionsSARS-CoV-2 antigen test advantages include low cost, wide availability and rapid turnaround time, making them important screening tests. The performance of antigen tests may vary with patient characteristics, so performance characteristics should be accounted for when designing testing strategies and interpreting results.

Surveillance of Respiratory Viruses in Long Term Care Facilities

ObjectiveTo assess the feasibility of conducting respiratory virus surveillance for residents of long term care facilities (LTCF) using simple nasal swab specimens and to describe the virology of acute respiratory infections (ARI) in LCTFs.IntroductionAlthough residents of LTCFs have high morbidity and mortality associated with ARIs, there is very limited information on the virology of ARI in LTCFs.[1,2] Moreover, most virological testing of LCTF residents is reactive and is triggered by a resident meeting selected surveillance criteria. We report on incidental findings from a prospective trial of introducing rapid influenza diagnostic testing (RIDT) in ten Wisconsin LTCFs over a two-year period with an approach of testing any resident with ARI.MethodsAny resident with new onset of respiratory symptoms consistent with ARI had a nasal swab specimen collected for RIDT by nursing staff. Following processing for RIDT (Quidel Sofia Influenza A+B FIA), the residual swab was placed into viral transport medium and forwarded to the Wisconsin State Laboratory of Hygiene and tested for influenza using RT-PCR (IVD CDC Human Influenza Virus Real-Time RT-PCR Diagnostic Panel), and for 17 viruses (Luminex NxTAG Respiratory Pathogen Panel [RPP]). The numbers of viruses in each of 7 categories [influenza A (FluA ), influenza B (FluB), coronaviruses (COR), human metapneumovirus (hMPV), parainfluenza (PARA), respiratory syncytial virus (RSV) and rhinovirus/enterovirus (R/E)], across the two years were compared using chi-square.ResultsTotals of 164 and 190 specimens were submitted during 2016-2017 and 2017-2018, respectively. RPP identified viruses in 56.2% of specimens, with no difference in capture rate between years (55.5% vs. 56.8%). Influenza A (21.5%), influenza B (16.5%), RSV (19.0%) and hMPV (16.5%) accounted for 73.5% of all detections, while coronaviruses (15.5%), rhino/enteroviruses (8.5%) and parainfluenza (2.5%) were less common. Specific distribution of viruses varied significantly across the two years (Table: X2=48.1, df=6; p&lt;0.001).ConclusionsSurveillance in LTCFs using nasal swabs collected for RIDT is highly feasible and yields virus identification rates similar to those obtained in clinical surveillance of ARI with collection of nasopharyngeal specimens by clinicians and those obtained in a school-based surveillance project of ARI with collection of combined nasal and oropharyngeal specimens collected by trained research assistants. Significant differences in virus composition occurred across the two study years. RSV varied little between years while hMPV demonstrated wide variation. Simple approaches to surveillance may provide a more comprehensive assessment of respiratory viruses in LTCF settings.References(1) Uršič T, Gorišek Miksić N, Lusa L, Strle F, Petrovec M. Viral respiratory infections in a nursing home: a six-month prospective study. BMC Infect Dis. 2016; 16: 637. Published online 2016 Nov 4. doi: 10.1186/s12879-016-1962-8(2) Masse S, Capai L, Falchi A. Epidemiology of Respiratory Pathogens among Elderly Nursing Home Residents with Acute Respiratory Infections in Corsica, France, 2013–2017. Biomed Res Int. 2017; 2017: 1423718. Published online 2017 Dec 17. doi: 10.1155/2017/1423718

Rapid Influenza Testing in an Austere Setting, Mongolia.

In 2015–2017, we helped rural Mongolian clinicians with poor infrastructure adopt rapid influenza diagnostic tests (RIDTs). In their hands, the Quidel Sofia Influenza A Test was both sensitive (75%) and specific (100%). If made widely available, such RIDTs would have the potential to markedly reduce influenza morbidity and mortality in Mongolia.

Sensitivity and Specificity of the Quidel Sofia Influenza A+B FIA Rapid Influenza Detection Test in Long-Term Care Facilities

BackgroundInfluenza is a significant pathogen for long-term care facility (LTCF) residents. As part of a randomized controlled trial to assess early detection of influenza in LTCFs, we deployed rapid influenza detection tests (RIDTs) at intervention LTCFs. Our primary objectives for this interim analysis were to evaluate the sensitivity and specificity of the Quidel Sofia® Influenza A+B Fluorescent Immunoassay RIDT in a high-risk, nontraditional population, and to describe the virology of acute respiratory infections (ARI) in LTCF residents.MethodsPersonnel at LCTFs identified cases of ARI, collected nasal specimens, and ran RIDTs from 10/21/2016 to 4/28/2017. The residual nasal swab and leftover lysis buffer were placed into a viral transport medium tube and sent to the Wisconsin State Laboratory of Hygiene for confirmatory influenza RT-PCR testing. In addition, all specimens were tested for other viruses using the Luminex NxTAG® Respiratory Pathogen Panel. Sensitivity and specificity of the Sofia RIDT were calculated using RT-PCR results as the reference standard.ResultsSpecimens were collected from 228 residents (mean age = 71.3 ± 22.4 years). The mean time from symptom onset to specimen collection was 1.4 ± 1.6 days (range: 0-7 days). Respiratory viruses were identified in 134/228 cases (58.8%); influenza viruses (A: 7.5% and B: 14.5%) were the most commonly detected virus by PCR, followed by rhinovirus/enterovirus (13.2%), RSV (11.0%) and coronaviruses (10.1%). The sensitivities of Sofia RIDT for influenza A and influenza B were 77.8% (95% CI: 52.4–93.6%) and 80.0% (95% CI: 61.4–92.3%), respectively, with specificities of 98.4% (95.3–99.7%) and 97.1% (93.4–99.1%), respectively. Overall performance assessment for influenza A or B yielded a sensitivity of 79.2% (65.0–89.5%) and specificity of 96.1% (91.7–98.6%). The estimated likelihood of discovering one of the first two influenza cases at a LTCF using this RIDT is estimated to be ≥95.7%.ConclusionAlthough a wide constellation of respiratory viruses cause ARIs within LTCF populations, influenza is very common. Early ARI recognition in residents, with testing shortly after symptom onset, likely contributed to high performance of the Sofia RIDT. Use of RIDTs allows early identification of influenza with high sensitivity and specificity in elderly LTCF residents.Disclosures J. Temte, Quidel: Investigator, Research support

New Method for Real Time Influenza Surveillance in Primary Care: A Wisconsin Research and Education Network (WREN) Supported Study.

The goal of public health infectious disease surveillance systems is to provide accurate laboratory results in near-real time. When it comes to influenza surveillance, most current systems are encumbered with inherent delays encountered in the real-life chaos of medical practice. To combat this, we implemented and tested near-real-time surveillance using a rapid influenza detection test (RIDT) coupled with immediate, wireless transmission of results to public health entities. A network of 19 primary care clinics across Wisconsin were recruited, including 4 sites already involved in ongoing influenza surveillance and 15 sites that were new to surveillance activities. Each site was provided with a Quidel Sofia Influenza A+B RIDT analyzer attached to a wireless router. Influenza test results, along with patient age, were transmitted immediately to a cloud-based server, automatically compiled, and forwarded to the surveillance team daily. Weekly counts of positive influenza A and B cases were compared with positive polymerase chain reaction (PCR) detections from an independent surveillance system within the state. Following Institutional Review Board (IRB) and institutional approvals, we recruited 19 surveillance sites, installed equipment, and trained staff within 4 months. Of the 1119 cases tested between September 15, 2013 and June 28, 2014, 316 were positive for influenza. The system provided early detection of the influenza outbreak in Wisconsin. The influenza peak between January 12 and 25, 2014, as well as the epidemic curve, closely matched that derived from the established PCR laboratory network (r = 0.927; P < .001). A network of influenza RIDTs with wireless transmission of results approximated the long-sought-after goal of real-time influenza surveillance. Results from the initial year strongly support this approach to highly accurate and timely influenza surveillance.

Detection of influenza A and B with the Alere ™ i Influenza A & B: a novel isothermal nucleic acid amplification assay.

BackgroundRapid influenza diagnostic tests (RIDTs) have an important role in clinical decision-making; however, the performances of currently available assays vary widely.ObjectivesWe evaluated the performance of the Alere™ i Influenza A&B (Alere™ iNAT), a rapid isothermal nucleic acid amplification assay that has recently received FDA clearance, for the detection of influenza A and B viruses during the Australian influenza season of 2013. Results were compared to two other RIDTs tested in parallel; Quidel Sofia® Influenza A+B fluorescent immunoassay (FIA) and Alere™ BinaxNOW® Influenza A & B immunochromatographic (ICT) assay.MethodsA total of 202 paired nasopharyngeal swabs collected from patients ≥16 years old with an influenza-like illness (ILI) were eluted in 2 ml of universal transport medium (UTM) that was used to perform all three RIDTs in parallel. Reverse-transcription polymerase chain reaction (RT-PCR) was used as the reference standard.ResultsCompared to RT-PCR, Alere™ iNAT detected 77·8% influenza A positive samples versus 71·4% and 44·4% for the Quidel Sofia® Influenza A+B FIA and BinaxNOW® Influenza A & B ICT assay, respectively. For influenza B, Alere™ iNAT detected 75% of those positive by RT-PCR, versus 33·3% and 25·0% for Sofia® and BinaxNOW®, respectively. The specificity of Alere™ iNAT was 100% for influenza A and 99% for influenza B.ConclusionsAlere™ i Influenza A&B is a promising new rapid influenza diagnostic assay with potential point-of-care applications.

Comparison of commercial influenza A virus assays in detecting avian influenza H7N9 among poultry cloacal swabs, China

BackgroundAvian H7N9 virus emerged in China in February 2013 and has since spread widely among China's poultry, causing numerous human infections. ObjectivesTo compare World Health Organization (WHO) and US commercial influenza assays in detecting avian H7N9 virus in poultry cloacal specimens. Study designBetween April 6 and July 15, 2013, 261 cloacal swabs were collected from commercial poultry in Nanjing and Wuxi City, Jiangsu Province, China. Swabs were screened with the WHO's influenza A and H7N9 real-time RT-PCR (qRT-PCR) assays. A blinded panel of 97 specimens (27 H7N9-positive and 70 influenza A-negative) was then used to compare 3 antigen based commercial assays (Remel Xpect Flu A&B, Quidel Quickvue influenza, and Quidel Sofia Influenza A+B), and 2 molecular commercial assays (Quidel Molecular Influenza A+B assay and Life Technologies VetMAX™-Gold SIV Detection Kit). None of these commercial assays were approved for use with poultry specimens. ResultsConsidering the WHO H7N9 qRT-PCR assay as the gold standard, all assays except the Quidel Quickvue influenza assay had high specificity (ranging from 96 to 99%). Regarding sensitivity, the Life Technologies VetMAX™-Gold SIV Detection Kit (100%; 95% CI 87–100%) and the Quidel Molecular Influenza A+B assay (85%; 95% CI 66–96%) performed the best. The sensitivities of the non-molecular antigen detection assays were either unable to detect small amounts of H7N9 viral RNA or were inhibited by specimen type. ConclusionsThe Life Technologies VetMAX™-Gold SIV Detection Kit and the Quidel Molecular Influenza A+B assay are comparable in performance to the WHO H7N9 qRT-PCR assay in detecting H7N9 from poultry cloacal specimens.