Rapid diagnostic testing for seasonal influenza: an evidence-based review and comparison with unaided clinical diagnosis

Global, regional and national estimates of influenza-attributable ischemic heart disease mortality

BACKGROUND

Influenza virus infection is associated with incident ischemic heart disease (IHD) events. Here, we estimate the global, regional, and national IHD mortality burden attributable to influenza.

METHODS

We used vital registration data from deaths in adults ≥50 years (13.2 million IHD deaths as underlying cause) to assess the relationship between influenza activity and IHD mortality in a non-linear meta-regression framework from 2010 to 2019. This derived relationship was then used to estimate the global influenza attributable IHD mortality. We estimated the population attributable fraction (PAF) of influenza for IHD deaths based on the relative risk associated with a given level of weekly influenza test positivity rate and multiplied PAFs by IHD mortality from the Global Burden of Disease study.

FINDINGS

Influenza activity was associated with increased risk of IHD mortality across all countries analyzed. The mean PAF of influenza for IHD mortality was 3.9% (95% uncertainty interval [UI] 2.5-5.3%), ranging from <1% to 10%, depending on country and year. Globally, 299,858 IHD deaths (95% UI 191,216-406,809) in adults ≥50 years could be attributed to influenza, with the highest rates per 100,000 population in the Central Europe, Eastern Europe and Central Asia Region (32.3; 95% UI 20.6-43.8), and in the North Africa and Middle East Region (26.7; 95% UI 17-36.2).

INTERPRETATION

Influenza may contribute substantially to the burden of IHD. Our results suggest that if there were no influenza, an average of 4% of IHD deaths globally would not occur.

FUNDING

Collaborative study funded by Sanofi Vaccines.

Point-of-Care Testing for the Emergency Department Patient: Quantity and Quality of the Available Evidence

CONTEXT.—

Point-of-care test (POCT) instruments produce lab results with rapid turnaround times. Based on that fact, emergency department (ED) POCT requests are predicated on the belief that rapid test turnaround times lead to improved care, typically a decreased ED length of stay (LOS).

OBJECTIVE.—

To compile the available peer-reviewed data regarding use of POCT in the ED with an emphasis on ED-LOS.

DATA SOURCES.—

An English-language PubMed search using the following free text terms: ("EMERGENCY" AND "POINT OF CARE") NOT ULTRASOUND as well as "RAPID INFECTIOUS DISEASE TESTING." In addition, the PubMed "similar articles" functionality was used to identify related articles that were not identified on the initial search.

CONCLUSIONS.—

Seventy-four references were identified that studied POCT ED use to determine if they resulted in significant changes in ED processes, especially ED-LOS. They were divided into 3 groups: viral-influenza (n = 24), viral-respiratory not otherwise specified (n = 8), and nonviral (n = 42). The nonviral group was further divided into the following groups: chemistry, cardiac, bacterial/strep, C-reactive protein, D-dimer, drugs of abuse, lactate, and pregnancy. Across all groups there was a trend toward a significantly decreased ED-LOS; however, a number of studies showed no change, and a third group was not assessed for ED-LOS. For POCT to improve ED-LOS it has to be integrated into existing ED processes such that a rapid test result will allow the patient to have a shorter LOS, whether it is to discharge or admission.

The Clinical Utility of Point-of-Care Tests for Influenza in Ambulatory Care: A Systematic Review and Meta-analysis

Background

Point-of-care tests (POCTs) for influenza are diagnostically superior to clinical diagnosis, but their impact on patient outcomes is unclear.

Methods

A systematic review of influenza POCTs versus usual care in ambulatory care settings. Studies were identified by searching six databases and assessed using the Cochrane risk of bias tool. Estimates of risk ratios (RR), standardised mean differences, 95% confidence intervals and I2 were obtained by random effects meta-analyses. We explored heterogeneity with sensitivity analyses and meta-regression.

Results

12,928 citations were screened. Seven randomized studies (n = 4,324) and six non-randomized studies (n = 4,774) were included. Most evidence came from paediatric emergency departments. Risk of bias was moderate in randomized studies and higher in non-randomized studies. In randomized trials, POCTs had no effect on admissions (RR 0.93, 95% CI 0.61–1.42, I2 = 34%), returning for care (RR 1.00 95% CI = 0.77–1.29, I2 = 7%), or antibiotic prescribing (RR 0.97, 95% CI 0.82–1.15, I2 = 70%), but increased prescribing of antivirals (RR 2.65, 95% CI 1.95–3.60; I2 = 0%). Further testing was reduced for full blood counts (FBC) (RR 0.80, 95% CI 0.69–0.92 I2 = 0%), blood cultures (RR 0.82, 95% CI 0.68–0.99; I2 = 0%) and chest radiography (RR 0.81, 95% CI 0.68–0.96; I2 = 32%), but not urinalysis (RR 0.91, 95% CI 0.78–w1.07; I2 = 20%). Time in the emergency department was not changed. Fewer non-randomized studies reported these outcomes, with some findings reversed or attenuated (fewer antibiotic prescriptions and less urinalysis in tested patients).

Conclusions

Point-of-care testing for influenza influences prescribing and testing decisions, particularly for children in emergency departments. Observational evidence shows challenges for real-world implementation.

Performance and ease of use of a molecular point-of-care test for influenza A/B and RSV in patients presenting to primary care

Annual influenza epidemics cause substantial morbidity and mortality, and the majority of patients with influenza-like illness present to primary care. Point-of-care influenza tests could support treatment decisions. It is critical to establish analytic performance of these platforms in real-life patient samples before uptake can be considered. We aimed to assess the analytical performance and ease of use of the cobas® Liat® PCR POCT in detecting influenza A/B and RSV in samples collected from patients with influenza-like illness in primary care. Sensitivity and specificity of the cobas® Liat® POCT are calculated in comparison with a commercial laboratory-based PCR test (Fast-Track Respiratory Pathogens 21 Plus kit (Fast-Track Diagnostics)). Samples with discordant results were analysed additionally by the RespiFinder 2Smart (PathoFinder) using an Extended Gold Standard (EGS). Acceptability was scored on a five-point Likert scale as well as a failure mode analysis of the cobas® Liat® POCT was performed. Nasal and oropharyngeal swabs were obtained from 140 children and nasopharyngeal swabs from 604 adults (744 patients). The cobas® Liat® POCT had a sensitivity and specificity of 100% (95% CI 99-100%) and 98.1% (95%CI 96.3-99%) for influenza A, 100% (95% CI 97.7-100%) and 99.7% (95%CI 98.7-99.9%) for influenza B and 100% (95% CI 87.1-100%) and 99.4% (95%CI 98.6-99.8%) for RSV, respectively. According to trained lab technicians, the cobas® Liat® POCT was considered easy-to-use, with a fast turn-around-time. Cobas® Liat® POCT is a promising decentralised test platform for influenza A/B and RSV in primary care as it provides fairly rapid results with excellent analytic performance. Point-of-care influenza tests could support treatment decisions in primary care. Cobas® Liat® POCT is a promising decentralised test platform for influenza A/B and RSV in primary care as it provides fairly rapid results with excellent analytic performance.

Impact of implementing respiratory point-of-care testing in a regional haemato-oncology unit

Respiratory point-of-care testing (POCT) for the detection of influenza A, influenza B and respiratory syncytial virus (RSV) was implemented in response to recent RSV outbreaks at a regional haemato-oncology unit in Glasgow. This descriptive study, undertaken pre- and post-POCT implementation, suggests that POCT reduces the time taken to receive results and increases diagnostic rates in outpatients. It is likely that the reduction in turnaround time afforded by POCT also leads to a faster time to antiviral treatment, prompt isolation and a reduction in the number of hospital-acquired infections.

High performance of rapid influenza diagnostic test and variable effectiveness of influenza vaccines in Mexico

OBJECTIVES

To evaluate the performance of rapid influenza diagnostic tests (RIDT) and influenza vaccines' effectiveness (VE) during an outbreak setting.

METHODS

We compared the performance of a RIDT with RT-PCR for influenza virus detection in influenza-like illness (ILI) patients enrolled during the 2016/17 season in Mexico City. Using the test-negative design, we estimated influenza VE in all participants and stratified by age, virus subtype, and vaccine type (trivalent vs quadrivalent inactivated vaccines). The protective value of some clinical variables was evaluated by regression analyses.

RESULTS

We enrolled 592 patients. RT-PCR detected 93 cases of influenza A(H1N1)pdm09, 55 of AH3N2, 141 of B, and 13 A/B virus infections. RIDT showed 90.7% sensitivity and 95.7% specificity for influenza A virus detection, and 91.5% sensitivity and 95.3% specificity for influenza B virus detection. Overall VE was 33.2% (95% CI: 3.0-54.0; p = 0.02) against any laboratory-confirmed influenza infection. VE estimates against influenza B were higher for the quadrivalent vaccine. Immunization and occupational exposure were protective factors against influenza.

CONCLUSIONS

The RIDT was useful to detect influenza cases during an outbreak setting. Effectiveness of 2016/17 influenza vaccines administered in Mexico was low but significant. Our data should be considered for future local epidemiological policies.

Detection of Influenza A and B Viruses and Respiratory Syncytial Virus by Use of Clinical Laboratory Improvement Amendments of 1988 (CLIA)-Waived Point-of-Care Assays: a Paradigm Shift to Molecular Tests

An accurate laboratory diagnosis of influenza, respiratory syncytial virus (RSV), and other respiratory viruses can help to guide patient management, antiviral therapy, infection prevention strategies, and epidemiologic monitoring. Influenza has been the primary driver of rapid laboratory testing due to its morbidity and mortality across all ages, the availability of antiviral therapy, which must be given early to have an effect, and the constant threat of new pandemic strains. Over the past 30 years, there has been an evolution in viral diagnostic testing, from viral culture to rapid antigen detection, and more recently, to highly sensitive nucleic acid amplification tests (NAAT), as well as a trend to testing at the point of care (POC). Simple rapid antigen immunoassays have long been the mainstay for POC testing for influenza A and B viruses and respiratory syncytial virus (RSV) but have been faulted for low sensitivity. In 2015, the first POC NAAT for the detection of influenza was approved by the Food and Drug Administration (FDA), ushering in a new era. In 2017, the FDA reclassified rapid influenza diagnostic tests (RIDTs) from class I to class II devices with new minimum performance standards and a requirement for annual reactivity testing. Consequently, many previously available RIDTs can no longer be purchased in the United States. In this review, recent developments in Clinical Laboratory Improvement Amendments of 1988 (CLIA)-waived testing for respiratory virus infections will be presented, with the focus on currently available FDA-cleared rapid antigen and molecular tests primarily for influenza A and B viruses and RSV.

Duration of viral shedding and factors associated with prolonged shedding among inpatients with influenza treated with oseltamivir: a prospective cohort study

The purpose of this study was to determine the rate of decline in the diagnostic yield of influenza PCR assay after oseltamivir administration, and to identify risk factors for prolonged shedding. This was a prospective observational study. We included adult inpatients with clinical signs of influenza during the influenza seasons 2015 and 2016, who had positive influenza PCR tests and who were treated with oseltamivir. Clinical follow-up and repeat PCR testing were performed on days 2, 4 and 6 after the first positive test. We defined prolonged shedders as patients who still required hospitalization and had a positive PCR assay on day 4. Risk factors for prolonged shedding were assessed in univariate and multivariate analyses. A total of 215 patients were included in our study. The median age was 64 years and 49.3% were men. The main influenza type was H1N1 (50.1%). Rates of PCR positivity among evaluable patients on days 2, 4 and 6 were 142/215 (66%), 50/78 (64.1%) and 20/30 (66.6%), respectively. Independent risk factors for prolonged shedding (50 patients) included hypoxemia [odds ratio (OR) 2.55, 95% confidence interval (1.3-5.1)] and lower diastolic blood pressure [OR 0.94, 95% CI (0.92-0.97)] on admission. Negative PCR tests taken more than 48 h after initiation of treatment had low diagnostic yield. More severe disease, manifested by hypoxemia and lower blood pressure, is associated with prolonged shedding on oseltamivir treatment.

Clinician-targeted interventions to influence antibiotic prescribing behaviour for acute respiratory infections in primary care: an overview of systematic reviews

BACKGROUND

Antibiotic resistance is a worldwide health threat. Interventions that reduce antibiotic prescribing by clinicians are expected to reduce antibiotic resistance. Disparate interventions to change antibiotic prescribing behaviour for acute respiratory infections (ARIs) have been trialled and meta-analysed, but not yet synthesised in an overview. This overview synthesises evidence from systematic reviews, rather than individual trials.

OBJECTIVES

To systematically review the existing evidence from systematic reviews on the effects of interventions aimed at influencing clinician antibiotic prescribing behaviour for ARIs in primary care.

METHODS

We searched the Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects (DARE), MEDLINE, Embase, CINAHL, PsycINFO, and Science Citation Index to June 2016. We also searched the reference lists of all included reviews. We ran a pre-publication search in May 2017 and placed additional studies in 'awaiting classification'.We included both Cochrane and non-Cochrane reviews of randomised controlled trials evaluating the effect of any clinician-focussed intervention on antibiotic prescribing behaviour in primary care. Two overview authors independently extracted data and assessed the methodological quality of included reviews using the ROBIS tool, with disagreements reached by consensus or by discussion with a third overview author. We used the GRADE system to assess the quality of evidence in included reviews. The results are presented as a narrative overview.

MAIN RESULTS

We included eight reviews in this overview: five Cochrane Reviews (33 included trials) and three non-Cochrane reviews (11 included trials). Three reviews (all Cochrane Reviews) scored low risk across all the ROBIS domains in Phase 2 and low risk of bias overall. The remaining five reviews scored high risk on Domain 4 of Phase 2 because the 'Risk of bias' assessment had not been specifically considered and discussed in the review Results and Conclusions. The trials included in the reviews varied in both size and risk of bias. Interventions were compared to usual care.Moderate-quality evidence indicated that C-reactive protein (CRP) point-of-care testing (risk ratio (RR) 0.78, 95% confidence interval (CI) 0.66 to 0.92, 3284 participants, 6 trials), shared decision making (odds ratio (OR) 0.44, 95% CI 0.26 to 0.75, 3274 participants, 3 trials; RR 0.64, 95% CI 0.49 to 0.84, 4623 participants, 2 trials; risk difference -18.44, 95% CI -27.24 to -9.65, 481,807 participants, 4 trials), and procalcitonin-guided management (adjusted OR 0.10, 95% CI 0.07 to 0.14, 1008 participants, 2 trials) probably reduce antibiotic prescribing in general practice. We found moderate-quality evidence that procalcitonin-guided management probably reduces antibiotic prescribing in emergency departments (adjusted OR 0.34, 95% CI 0.28 to 0.43, 2605 participants, 7 trials). The overall effect of these interventions was small (few achieving greater than 50% reduction in antibiotic prescribing, most about a quarter or less), but likely to be clinically important.Compared to usual care, shared decision making probably makes little or no difference to reconsultation for the same illness (RR 0.87, 95% CI 0.74 to 1.03, 1860 participants, 4 trials, moderate-quality evidence), and may make little or no difference to patient satisfaction (RR 0.86, 95% CI 0.57 to 1.30, 1110 participants, 2 trials, low-quality evidence). Similarly, CRP testing probably has little or no effect on patient satisfaction (RR 0.79, 95% CI 0.57 to 1.08, 689 participants, 2 trials, moderate-quality evidence) or reconsultation (RR 1.08, 95% CI 0.93 to 1.27, 5132 participants, 4 trials, moderate-quality evidence). Procalcitonin-guided management probably results in little or no difference in treatment failure in general practice compared to normal care (adjusted OR 0.95, 95% CI 0.73 to 1.24, 1008 participants, 2 trials, moderate-quality evidence), however it probably reduces treatment failure in the emergency department compared to usual care (adjusted OR 0.76, 95% CI 0.61 to 0.95, 2605 participants, 7 trials, moderate-quality evidence).The quality of evidence for interventions focused on clinician educational materials and decision support in reducing antibiotic prescribing in general practice was either low or very low (no pooled result reported) and trial results were highly heterogeneous, therefore we were unable draw conclusions about the effects of these interventions. The use of rapid viral diagnostics in emergency departments may have little or no effect on antibiotic prescribing (RR 0.86, 95% CI 0.61 to 1.22, 891 participants, 3 trials, low-quality evidence) and may result in little to no difference in reconsultation (RR 0.86, 95% CI 0.59 to 1.25, 200 participants, 1 trial, low-quality evidence).None of the trials in the included reviews reported on management costs for the treatment of an ARI or any associated complications.

AUTHORS' CONCLUSIONS

We found evidence that CRP testing, shared decision making, and procalcitonin-guided management reduce antibiotic prescribing for patients with ARIs in primary care. These interventions may therefore reduce overall antibiotic consumption and consequently antibiotic resistance. There do not appear to be negative effects of these interventions on the outcomes of patient satisfaction and reconsultation, although there was limited measurement of these outcomes in the trials. This should be rectified in future trials.We could gather no information about the costs of management, and this along with the paucity of measurements meant that it was difficult to weigh the benefits and costs of implementing these interventions in practice.Most of this research was undertaken in high-income countries, and it may not generalise to other settings. The quality of evidence for the interventions of educational materials and tools for patients and clinicians was either low or very low, which prevented us from drawing any conclusions. High-quality trials are needed to further investigate these interventions.

Influenza

Influenza is an acute respiratory illness, caused by influenza A, B, and C viruses, that occurs in local outbreaks or seasonal epidemics. Clinical illness follows a short incubation period and presentation ranges from asymptomatic to fulminant, depending on the characteristics of both the virus and the individual host. Influenza A viruses can also cause sporadic infections or spread worldwide in a pandemic when novel strains emerge in the human population from an animal host. New approaches to influenza prevention and treatment for management of both seasonal influenza epidemics and pandemics are desirable. In this Seminar, we discuss the clinical presentation, transmission, diagnosis, management, and prevention of seasonal influenza infection. We also review the animal-human interface of influenza, with a focus on current pandemic threats.

Implementing an Antibiotic Stewardship Program: Guidelines by the Infectious Diseases Society of America and the Society for Healthcare Epidemiology of America

Evidence-based guidelines for implementation and measurement of antibiotic stewardship interventions in inpatient populations including long-term care were prepared by a multidisciplinary expert panel of the Infectious Diseases Society of America and the Society for Healthcare Epidemiology of America. The panel included clinicians and investigators representing internal medicine, emergency medicine, microbiology, critical care, surgery, epidemiology, pharmacy, and adult and pediatric infectious diseases specialties. These recommendations address the best approaches for antibiotic stewardship programs to influence the optimal use of antibiotics.

A prospective study to assess the diagnostic performance of the Sofia(®) Immunoassay for Influenza and RSV detection

BACKGROUND

Respiratory viruses RSV and influenza A and B viruses are responsible for important disease outbreaks during the winter season in temperate climate regions. Rapid diagnostic tests (RDTs) are assays designed to yield a rapid diagnosis, which facilitates patient management. The Sofia Influenza A+B Fluorescence Immunoassay and Sofia RSV Fluorescence Immunoassay are RDTs for Influenza and RSV detection that employ a new technology to enhance their sensitivity.

OBJECTIVES

Sensitivity, specificity and positive and negative predictive values of the assays were calculated compared with the reference diagnostic method: real-time RT-PCR.

STUDY DESIGN

A prospective evaluation was carried out on 1065 respiratory samples for Sofia Influenza A+B FIA and on 261 samples for Sofia RSV FIA from November 2013 to April 2014.

RESULTS

The sensitivities of the Sofia Influenza A+B FIA for influenza A and influenza B detection were, respectively, 75.3% (244/324) and 50.0% (8/16). The sensitivity of the Sofia RSV FIA was 92.1% (128/139). There were no differences in Sofia FIA performance depending on the virus subtype.

CONCLUSIONS

The results showed high sensitivity and specificity values for influenza A and RSV detection, but values were lower for influenza B. More information is needed regarding the performance for influenza B given the small number of positive samples assessed.

Performance of the Cobas(®) Influenza A/B Assay for Rapid Pcr-Based Detection of Influenza Compared to Prodesse ProFlu+ and Viral Culture

Rapid and accurate diagnosis of influenza is important for patient management and infection control. We determined the performance of the cobas^® Influenza A/B assay, a rapid automated nucleic acid assay performed on the cobas^® Liat System for qualitative detection of influenza A and influenza B from nasopharyngeal (NP) swab specimens. Retrospective frozen and prospectively collected NP swabs from patients with signs and symptoms of influenza collected in universal transport medium (UTM) were tested at multiple sites including CLIA-waived sites using the cobas® Influenza A/B assay. Results were compared to the Prodesse Pro-Flu+ assay and to viral culture. Compared to the Prodesse ProFlu+ Assay, sensitivities of the cobas^® Influenza A/B assay for influenza A and B were 97.7 and 98.6%, respectively; specificity was 99.2 and 99.4%. Compared to viral culture, the cobas^® Influenza A/B assay showed sensitivities of 97.5 and 96.9% for influenza virus A and B, respectively; specificities were 97.9% for both viruses. Polymerase chain reaction (PCR)/sequencing showed that the majority of viral culture negative but cobas^® Influenza A/B positive results were true positive results, indicating that the cobas^® Influenza A/B assay has higher sensitivity compared to viral culture.

In conclusion, the excellent accuracy, rapid time to result, and remarkable ease of use make the cobas^® Influenza A/B nucleic acid assay for use on the cobas^® Liat System a highly suitable point-of-care solution for the management of patients with suspected influenza A and B infection.

Evaluation of a new rapid diagnostic test for the detection of influenza and RSV

INTRODUCTION

Influenza viruses and respiratory syncytial virus (RSV) can cause an acute respiratory disease that occurs seasonally in epidemic waves. This retrospective study was conducted to evaluate the Sofia(®) Influenza A+B and the Sofia(®) RSV fluorescence immunoassays (FIAs), two novel rapid detection tests (RDTs) for influenza A and B and RSV.

METHODS

Two hundred and nine breath samples were selected from patients with respiratory symptoms determined to be positive/negative for influenza A, influenza B or RSV using one of the reference diagnostic techniques, cell culture and/or RT-PCR (Simplexa™Flu A/B & RSV). The Sofia Influenza A+B FIA was tested on 123 samples (63 from children and 60 from adults) and the Sofia RSV FIA was tested on 86 pediatric samples. Sensitivity and specificity values of both assays were calculated assuming the reference techniques as the gold standard.

RESULTS

Sensitivity and specificity values for the Sofia Influenza A+B FIA were 73.1% and 97.8%, respectively. Sensitivity and specificity values for the Sofia RSV FIA were 87.5% and 86.7%, respectively.

CONCLUSION

The sensitivity results obtained for the two assays were considerably higher than those reported for other RDTs. In conclusion, the Sofia Influenza A+B and the Sofia RSV FIAs are appropriate tools for the rapid diagnosis of these viruses.

Can newly developed, rapid immunochromatographic antigen detection tests be reliably used for the laboratory diagnosis of influenza virus infections?

Five years ago, the Point-Counterpoint series was launched. The initial article asked about the role of rapid immunochromatographic antigen testing in the diagnosis of influenza A virus 2009 H1N1 infection (D. F. Welch and C. C. Ginocchio, J Clin Microbiol 48:22-25, 2010, http://dx.doi.org/10.1128/JCM.02268-09). Since that article, not only have major changes been made in immunochromatographic antigen detection (IAD) testing for the influenza viruses, but there has also been rapid development of commercially available nucleic acid amplification tests (NAATs) for influenza virus detection. Further, a novel variant of influenza A, H7N9, has emerged in Asia, and H5N1 is also reemergent. In that initial article, the editor of this series, Peter Gilligan, identified two issues that required further consideration. One was how well IAD tests worked in clinical settings, especially in times of antigen drift and shift. The other was the role of future iterations of influenza NAATs and whether this testing would be available in a community hospital setting. James Dunn, who is Director of Medical Microbiology and Virology at Texas Children's Hospital, has extensive experience using IAD tests for diagnosing influenza. He will discuss the application and value of these tests in influenza diagnosis. Christine Ginocchio, who recently retired as the Senior Medical Director, Division of Infectious Disease Diagnostics, North Shore-LIJ Health System, and now is Vice President for Global Microbiology Affairs at bioMérieux, Durham, NC, wrote the initial counterpoint in this series, where she advocated the use of NAATs for influenza diagnosis. She will update us on the commercially available NAAT systems and explain what their role should be in the diagnosis of influenza infection.

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

Background

Rapid influenza diagnostic tests (RIDTs) have an important role in clinical decision-making; however, the performances of currently available assays vary widely.

Objectives

We 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.

Methods

A 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.

Results

Compared 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.

Conclusions

Alere™ i Influenza A&B is a promising new rapid influenza diagnostic assay with potential point-of-care applications.

Is influenza-like illness a useful concept and an appropriate test of influenza vaccine effectiveness?

PURPOSE

To assess the utility of "influenza-like illness" (ILI) and whether it appropriately tests influenza vaccine effectiveness.

PRINCIPAL RESULTS

The WHO and CDC definitions of "influenza-like illness" are similar. However many studies use other definitions, some not specifying a temperature and requiring specific respiratory and/or systemic symptoms, making many samples non-comparable. Most ILI studies find less than 25% of cases are RT-PCR-positive, those which test for other viruses and bacteria usually find multiple other pathogens, and most identify no pathogen in about 50% of cases. ILI symptom and symptom combinations do not have high sensitivity or specificity in identifying PCR-positive influenza cases. Rapid influenza diagnostic tests are increasingly used to screen ILI cases and they have low sensitivity and high specificity when compared to RT-PCR in identifying influenza.

MAIN CONCLUSIONS

The working diagnosis of ILI presumes influenza may be involved until proven otherwise. Health care workers would benefit by renaming the WHO and CDC ILI symptoms and signs as "acute respiratory illness" and also using the WHO acute severe respiratory illness definition if the illness is severe and meets this criterion. This renaming would shift attention to identify the viral and bacterial pathogens in cases and epidemics, identify new pathogens, implement vaccination plans appropriate to the identified pathogens, and estimate workload during the viral season. Randomised controlled trials testing the effectiveness of influenza vaccine require all participants to be assessed by a gold standard (RT-PCR). ILI has no role in measuring influenza vaccine effectiveness. ILI is well established in the literature and in the operational definition of many surveillance databases and its imprecise definition may be inhibiting progress in research and treatment. The current ILI definition could with benefit be renamed "acute respiratory illness," with additional definitions for "severe acute respiratory illness" (SARI) with RT-PCR testing for pathogens to facilitate prevention and treatment.

Influenza diagnosis and vaccination in Poland

In Poland between several thousand and several million cases of influenza and suspected influenza cases are registered, depending on the epidemic season. A variety of methods are available for the detection of the influenza viruses responsible for respiratory infection starting with the isolation of the virus in chick embryos or in cell lines such as MDCK, VERO, etc., and finishing with a variety of modifications of the classical PCR molecular biology such as PCR multiplex and Real-Time. The most effective way to combat influenza is through vaccination. Regular vaccination is one of the few steps that may be taken to protect individuals, especially in high-risk groups, from the potential and serious complications of influenza. In many countries, including Poland, despite the recommendations, the rate of vaccination against influenza is still low in all age groups. In the epidemic season 2011/2012, the level of distribution of the seasonal influenza vaccines was 4.5% of the population.

Detection of influenza A and B viruses with the Sofia analyzer: a novel, rapid immunofluorescence-based in vitro diagnostic device

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.

Evaluation of the limit of detection of the BD Veritor™ system flu A+B test and two rapid influenza detection tests for influenza virus

We evaluated the limits of detection of 3 rapid influenza diagnostic tests-BD Veritor™ System for Flu A+B, Binax NOW® Influenza A+B, and QuickVue® Influenza-for influenza strains circulating in 2010-2012. Limits of detection varied by influenza strain, with Veritor™ Flu A+B test showing the lowest limit of detection for all strains.

Evaluation of five rapid diagnostic kits for influenza A/B virus

Influenza viruses cause seasonal epidemics associated with high morbidity and mortality. However, even during periods of epidemic prevalence, clinical diagnoses are problematic. Rapid diagnostic tests for the detection of pandemic influenza A/B virus are valuable for their ease of use. Many rapid influenza diagnostic kits were introduced recently in the Republic of Korea (ROK), including Directizen EZ Flu A and B (Becton Dickinson, Sparks, USA), Binax Now Influenza A/B antigen kit (Binax, Portland, USA), Genedia influenza Ag (Green Cross, Yongin, ROK), Humasis Influenza A/B antigen test (Humasis, Anyang, ROK), and SD Bioline rapid influenza kit (Standard Diagnostics, Yongin, ROK). The objective of this study was to evaluate the performance of these five rapid diagnostic kits. The results were compared with those of viral culture and reverse transcription (RT)-PCR. A total of 253 nasopharyngeal swabs were analyzed from 253 patients (influenza A, n=67; B, n=86; negative samples, n=100). The specimens were tested immediately by conventional influenza virus culture and RT-PCR, stored at -80°C, and tested using five rapid test kits. The performance of the five rapid tests kits varied with sensitivities between 71.0 and 82.1% and between 37.2 and 47.7% for detecting influenza A and B, respectively. For influenza A, the sensitivities of the Directizen EZ Flu A and B, Binax Now Influenza A/B antigen kit, Genedia influenza Ag, Humasis Influenza A/B antigen test, and SD Bioline rapid influenza kits were 82.1%, 71.0%, 76.1%, 79.1%, and 82.1%, respectively; those for influenza B were 40.7%, 37.2%, 40.7%, 41.8%, and 47.7%, respectively. The specificity of all rapid tests was 100%. Commercial influenza antigen detection assays are useful tools for the rapid diagnosis of influenza. However, confirmatory testing is always recommended.

Neuraminidase inhibitors for preventing and treating influenza in children (published trials only)

BACKGROUND

During epidemics, influenza attack rates in children may exceed 40%. Options for prevention and treatment currently include the neuraminidase inhibitors zanamivir and oseltamivir. Laninamivir octanoate, the prodrug of laninamivir, is currently being developed.

OBJECTIVES

To assess the efficacy, safety and tolerability of neuraminidase inhibitors in the treatment and prevention of influenza in children.

SEARCH METHODS

For this update we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 1) which includes the Acute Respiratory Infections Group's Specialised Register, MEDLINE (1966 to January week 2, 2011) and EMBASE (January 2010 to January 2011).

SELECTION CRITERIA

Double-blind, randomised controlled trials (RCTs) comparing neuraminidase inhibitors with placebo or other antiviral drugs in children aged up to and including 12 years. We also included safety and tolerability data from other types of studies.

DATA COLLECTION AND ANALYSIS

Four review authors selected studies, assessed study quality and extracted data for the current and previous versions of this review. We analysed data separately for oseltamivir versus placebo, zanamivir versus placebo and laninamivir octanoate versus oseltamivir.

MAIN RESULTS

Six treatment trials involving 1906 children with clinical influenza and 450 children with influenza diagnosed on rapid near-patient influenza testing were included. Of these 2356 children, 1255 had laboratory-confirmed influenza. Three prophylaxis trials involving 863 children exposed to influenza were also included. In children with laboratory-confirmed influenza oseltamivir reduced median duration of illness by 36 hours (26%, P < 0.001). One trial of oseltamivir in children with asthma who had laboratory-confirmed influenza showed only a small reduction in illness duration (10.4 hours, 8%), which was not statistically significant (P = 0.542). Laninamivir octanoate 20 mg reduced symptom duration by 2.8 days (60%, P < 0.001) in children with oseltamivir-resistant influenza A/H1N1. Zanamivir reduced median duration of illness by 1.3 days (24%, P < 0.001). Oseltamivir significantly reduced acute otitis media in children aged one to five years with laboratory-confirmed influenza (risk difference (RD) -0.14, 95% confidence interval (CI) -0.24 to -0.04). Prophylaxis with either zanamivir or oseltamivir was associated with an 8% absolute reduction in developing influenza after the introduction of a case into a household (RD -0.08, 95% CI -0.12 to -0.05, P < 0.001). The adverse event profile of zanamivir was no worse than placebo but vomiting was more commonly associated with oseltamivir (number needed to harm = 17, 95% CI 10 to 34). The adverse event profiles of laninamivir octanoate and oseltamivir were similar.

AUTHORS' CONCLUSIONS

Oseltamivir and zanamivir appear to have modest benefit in reducing duration of illness in children with influenza. However, our analysis was limited by small sample sizes and an inability to pool data from different studies. In addition, the inclusion of data from published trials only may have resulted in significant publication bias. Based on published trial data, oseltamivir reduces the incidence of acute otitis media in children aged one to five years but is associated with a significantly increased risk of vomiting. One study demonstrated that laninamivir octanoate was more effective than oseltamivir in shortening duration of illness in children with oseltamivir-resistant influenza A/H1N1. The benefit of oseltamivir and zanamivir in preventing the transmission of influenza in households is modest and based on weak evidence. However, the clinical efficacy of neuraminidase inhibitors in 'at risk' children is still uncertain. Larger high-quality trials are needed with sufficient power to determine the efficacy of neuraminidase inhibitors in preventing serious complications of influenza (such as pneumonia or hospital admission), particularly in 'at risk' groups.

Discrimination of influenza A subtype by antibodies recognizing host-specific amino acids in the viral nucleoprotein

BACKGROUND

Nucleoprotein (NP) of influenza viruses is utilized to differentiate between the A, B, and C viral serotypes. The availability of influenza genome sequence data has allowed us to identify specific amino acids at particular positions in viral proteins, including NP, known as "signature residues," which can be used to discriminate human influenza A viruses from H5N1 highly pathogenic avian influenza in human cases (HPAI) and pandemic H1N1(2009) (H1N1/2009) viruses.

METHODS

Screening and epitope mapping of monoclonal antibodies (mAb) against NP of influenza A, which reacted differently with NP from human influenza A virus from HPAI and H1N1/2009 A virus. To identify the epitope(s) responsible for the discrimination of viral NP by mAbs, we prepared mutant NP proteins in the 293 cell expression system because some of the mAbs reacted with non-linear epitopes.

RESULTS AND CONCLUSIONS

In the present study, we identified 3 mAbs. The results of epitope mapping showed that the epitopes were located at the signature residues. These results indicated that signature residues of NP could discriminate influenza A viruses from different origin.

Neuraminidase inhibitors for preventing and treating influenza in children

BACKGROUND

During epidemics, influenza attack rates in children may exceed 40%. Options for prevention and treatment currently include the neuraminidase inhibitors zanamivir and oseltamivir. Laninamivir octanoate, the prodrug of laninamivir, is currently being developed.

OBJECTIVES

To assess the efficacy, safety and tolerability of neuraminidase inhibitors in the treatment and prevention of influenza in children.

SEARCH METHODS

For this update we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 1) which includes the Acute Respiratory Infections Group's Specialised Register, MEDLINE (1966 to January week 2, 2011) and EMBASE (January 2010 to January 2011).

SELECTION CRITERIA

Double-blind, randomised controlled trials (RCTs) comparing neuraminidase inhibitors with placebo or other antiviral drugs in children aged up to and including 12 years. We also included safety and tolerability data from other types of studies.

DATA COLLECTION AND ANALYSIS

Four review authors selected studies, assessed study quality and extracted data for the current and previous versions of this review. We analysed data separately for oseltamivir versus placebo, zanamivir versus placebo and laninamivir octanoate versus oseltamivir.

MAIN RESULTS

Six treatment trials involving 1906 children with clinical influenza and 450 children with influenza diagnosed on rapid near-patient influenza testing were included. Of these 2356 children, 1255 had laboratory-confirmed influenza. Three prophylaxis trials involving 863 children exposed to influenza were also included. In children with laboratory-confirmed influenza oseltamivir reduced median duration of illness by 36 hours (26%, P < 0.001). One trial of oseltamivir in children with asthma who had laboratory-confirmed influenza showed only a small reduction in illness duration (10.4 hours, 8%), which was not statistically significant (P = 0.542). Laninamivir octanoate 20 mg reduced symptom duration by 2.8 days (60%, P < 0.001) in children with oseltamivir-resistant influenza A/H1N1. Zanamivir reduced median duration of illness by 1.3 days (24%, P < 0.001). Oseltamivir significantly reduced acute otitis media in children aged one to five years with laboratory-confirmed influenza (risk difference (RD) -0.14, 95% confidence interval (CI) -0.24 to -0.04). Prophylaxis with either zanamivir or oseltamivir was associated with an 8% absolute reduction in developing influenza after the introduction of a case into a household (RD -0.08, 95% CI -0.12 to -0.05, P < 0.001). The adverse event profile of zanamivir was no worse than placebo but vomiting was more commonly associated with oseltamivir (number needed to harm = 17, 95% CI 10 to 34). The adverse event profiles of laninamivir octanoate and oseltamivir were similar.

AUTHORS' CONCLUSIONS

Oseltamivir and zanamivir appear to have modest benefit in reducing duration of illness in children with influenza. However, our analysis was limited by small sample sizes and an inability to pool data from different studies. Oseltamivir reduces the incidence of acute otitis media in children aged one to five years but is associated with a significantly increased risk of vomiting. One study demonstrated that laninamivir octanoate was more effective than oseltamivir in shortening duration of illness in children with oseltamivir-resistant influenza A/H1N1. The benefit of oseltamivir and zanamivir in preventing the transmission of influenza in households is modest and based on weak evidence. However, the clinical efficacy of neuraminidase inhibitors in 'at risk' children is still uncertain. Larger high-quality trials are needed with sufficient power to determine the efficacy of neuraminidase inhibitors in preventing serious complications of influenza (such as pneumonia or hospital admission), particularly in 'at risk' groups.