Abstract Background The potential benefits of using rapid influenza diagnostic tests (RIDTs) in urgent care facilities for clinical care and prescribing practices are understudied. We compared antiviral and antibiotic prescribing, imaging, and laboratory ordering in clinical encounters with and without RIDT results. Methods We compared patients with acute respiratory infection (ARI) symptoms who received an RIDT and patients who did not at 2 urgent care facilities. Primary analysis using 1-to-1 exact matching resulted in 1145 matched pairs to which McNemar 2 × 2 tests were used to assess the association between the likelihood of prescribing, imaging/laboratory ordering, and RIDT use. Secondary analysis compared the same outcomes using logistic regression among the RIDT-tested population between participants who tested negative (RIDT(−)) and positive (RIDT(+)). Results Primary analysis revealed that compared to the non-RIDT-tested population, RIDT(+) patients were more likely to be prescribed antivirals (OR, 10.23; 95% CI, 5.78–19.72) and less likely to be prescribed antibiotics (OR, 0.15; 95% CI, .08–.27). Comparing RIDT-tested to non-RIDT-tested participants, RIDT use increased antiviral prescribing odds (OR, 3.07; 95% CI, 2.25–4.26) and reduced antibiotic prescribing odds (OR, 0.52; 95% CI, .43–.63). Secondary analysis identified increased odds of prescribing antivirals (OR, 28.21; 95% CI, 18.15–43.86) and decreased odds of prescribing antibiotics (OR, 0.20; 95% CI, .13–.30) for RIDT(+) participants compared with RIDT(−). Conclusions Use of RIDTs in patients presenting with ARI symptoms influences clinician diagnostic and treatment decision-making, which could lead to improved patient outcomes, population-level reductions in influenza burden, and a decreased threat of antibiotic resistance.

Rapid influenza diagnostic tests (RIDT) demonstrate varying sensitivities, often necessitating reverse transcriptase polymerase chain reaction (RT-PCR) to confirm results. The two methods generally require separate specimens. Using the same anterior nasal swab for both RIDT and molecular confirmation would reduce cost and waste and increase patient comfort. The aim of this study was to determine if RIDT residual nasal swab (rNS) specimens are adequate for RT-PCR and whole genome sequencing (WGS). We performed RT-PCR and WGS on paired rNS and nasopharyngeal or oropharyngeal (NP/OP) swab specimens that were collected from primary care patients across all ages. We randomly selected 199 and 40 paired specimens for RT-PCR and WGS, respectively, from the 962 paired surveillance specimens collected during the 2014-2015 influenza season. Sensitivity and specificity for rNS specimens were 81.3% and 96.7%, respectively, as compared to NP/OP specimens. The mean cycle threshold (Ct) value for the NP/OP specimen was significantly lower when the paired specimens were both positive than when the NP/OP swab was positive and the nasal swab was negative (25.5 vs 29.5; p<0.001). Genomic information was extracted from all 40 rNS specimens and 37 of the 40 NP/OP specimens. Complete WGS reads were available for 67.5% (14 influenza A; 13 influenza B) of the rNS specimens and 59.5% (14 influenza A; 8 influenza B) of the NP/OP specimens. It is feasible to use a single anterior nasal swab for RIDT followed by RT-PCR and/or WGS. This approach may be appropriate in situations where training and supplies are limited. Additional studies are needed to determine if residual nasal swabs from other rapid diagnostic tests produce similar results.

Background: School closures were mandated in response to COVID-19 as a nonpharmaceutical intervention. Influenza A was widespread in Wisconsin at the time of mandate, March 18, 2020, allowing its evaluation for influenza interruption. Methods: Daily percent positivity of influenza A among primary care patients who received a rapid influenza diagnostic test was evaluated throughout two influenza seasons while schools were open and closed. Results: Median deviation from baseline of percent positivity was significantly lower when schools were closed than when open (-2.25% vs 1.08%; H=7.84; P=0.005). Median deviation in percent positivity for the eight days following statewide school closure was -20.0. Discussion: Unprecedented closures of all Wisconsin schools was associated with a rapid decline in influenza A. Additional evaluations within other jurisdictions are warranted.

Objective Demonstrate performance of the Virena Global Wireless Surveillance System, an automated platform utilized in conjunction with the Sofia FIA Analyzer, for near real-time transmission of infectious disease test results to public health and other healthcare organizations. Introduction Public health agencies worldwide all enjoy the same mission—providing healthcare warnings, guidance, and support to the public and healthcare professionals they represent. A critical element in achieving this mission is accessing timely and comprehensive surveillance information about disease in their regions of responsibility. Advances in diagnostic technologies for infectious disease and in the wireless conveyance of information hold great promise for advancing the quality of surveillance information and in facilitating the delivery of timely, accurate, and impactful public health information. Quidel Corporation has developed a cloud–based, wireless communications system that is fully integrated with its Sofia fluorescence immunoassay (FIA) platform for rapid, point-of-care diagnosis of infectious disease. The system, called the Virena Global Wireless Surveillance System (hereinafter, Virena) provides test results to public health organizations and other appropriate entities in near-real time. Currently, more than 4,000 Sofia instruments are transmitting results automatically by Virena. This presentation describes the use of Virena in surveilling influenza in the U.S. in the 2016-2017 influenza season, when over 700,000 influenza-like-illness (ILI) patient results were transmitted. The methods employed, results, and the promise of this innovative system will be discussed. Methods The Sofia Fluorescent Immunoassay Analyzer (FIA) is a small FDA-cleared, CLIA-waived bench top device that uses immunofluorescence-based, lateral-flow technology for rapid analyte detection within 15 minutes for influenza. With Sofia2, a recent upgrade, positive influenza test results can be obtained in as few as 3 minutes, depending on virus levels. The results are encrypted, and automatically transmitted by Virena--often within 5 seconds--to a dual cloud system for further encryption and formatting. The test results (also including location, date, and patient age) are subsequently pushed to participating public health and healthcare organizations for daily collection and analysis. Healthcare providers utilizing the Virena system may also access their own data and facility-de-identified regional and national data, using a password-enabled internet application called MyVirena.com. Results Between August 1, 2016 and October 6, 2017, 706,654 ILI patient results were transmitted by Virena from over 3,000 clinical sites in the United States. The influenza positivity rate (influenza A and B combined) peaked on February 9th at 33% and maintained this level for two weeks (Figure 1). During this period, as many as 7,048 results were transmitted by Virena per day. Influenza A activity peaked on the same day at 26%, and influenza B peaked at 18% nearly 6.5 weeks later. In the six months from December 15 th to June 15 th , the influenza positivity rate for patients with ILI was 10% or greater in the United States. Data analysis for individual states revealed significant differences in time of onset of influenza and in the peak positivity rates. For example, the state of Arizona experienced peak positivity rates for influenza activity (42%) as late as mid-May, driven largely by influenza B. In California, influenza A peaked at 43% on January 16 th and maintained a positivity rate greater than 15% for nearly three months, while influenza B averaged below 4% for the entire period. Age-specific analysis showed that children in the 2 to 18 year old group had the highest positivity rate (44%, n=251,756) and the longest incidence period. Virena data demonstrated similar influenza activity trends on national and regional levels as that depicted by the clinical laboratory and NREVSS data collected by the CDC; however, the Virena data were collected and reported sooner (Figure 2). Conclusions The Virena system represents a major stride for disease surveillance, providing clinical testing data in near real-time time, with local, national, and global scope. This first substantial evaluation of the Virena system, with over 4,000 transmitting Sofia Analyzers, demonstrates capabilities for near real-time assessment of disease onset, regionally varying positivity rates, durations of outbreaks, differential assessment of influenza A and B prevalence, and dynamic mapping throughout the year. With expanding regional and metropolitan coverage, the Virena system holds promise as both a powerful surveillance tool, and as a valuable resource for healthcare quality initiatives, epidemiological research, and the development of new mathematical models for influenza forecasting .

Introduction: 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. Methods: 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. Results: 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). Conclusions: 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.

Background: Variability in the timing of influenza epidemics has been observed across global and regional scales, but this variability has not been studied extensively at finer spatial scales. As such, the aim of this study was to test whether influenza cases were synchronized across sites and/or age-groups within a major city.Methods: We used influenza cases identified by rapid influenza tests from a network of clinics across Phoenix, AZ during the 2015-2016 influenza A season. We used a combination of KS tests and a bootstrapping approach to evaluate whether the temporal distribution of cases varied by site and/or age group.Results: Our analysis indicates that the timing of influenza cases during the 2015-2016 seasonal influenza epidemic were generally synchronized across sites and age groups. That said, we did observe some statistically significant differences in the timing of cases across some sites, and by site and age group. We found no evidence that influenza activity consistently begins or peaks earlier in children than in adults.Conclusions: To our knowledge, this is the first study to investigate differences in the intra-urban timing of influenza using influenza-specific case data. We were able to show evidence that influenza cases are not entirely synchronized across an urban area, but the differences we observed were relatively minor. It is important to understand the geographic scale at which influenza is synchronized in order to gain a better understanding of local transmission dynamics, and to determine the appropriate geographic scale that influenza surveillance data should be aggregated for prediction and warning systems.

This report describes the clinical evaluation of a novel fluorescent immunoassay (FIA), Sofia Influenza A+B FIA (Quidel, San Diego, CA), for the rapid detection and differentiation of influenza A and B viruses. A total of 2,047 subjects provided nasal swabs and nasopharyngeal swabs or aspirates. The overall sensitivity and specificity for influenza A virus vs virus culture were 94% and 95%, respectively, and for influenza B virus were 89% and 96%, respectively. Fourteen hundred and sixty-one specimens were available for testing with reverse transcriptase-polymerase chain reaction (RT-PCR). The sensitivity of the Sofia Influenza A+B FIA for detecting influenza A and B viruses compared with the RT-PCR method was 78% and 86%, respectively. A high percentage of the positive specimens had low cycle threshold values, and almost all of these were positive with the Sofia test. This high level of sensitivity demonstrates that the Sofia influenza A+B FIA could improve the usefulness of rapid influenza virus testing.