Accuracy and interpretation of rapid influenza tests in children

Determining the timing of respiratory syncytial virus (RSV) epidemics: a systematic review, 2016 to 2021; method categorisation and identification of influencing factors

BackgroundThere is currently no standardised approach to estimate respiratory syncytial virus (RSV) epidemics' timing (or seasonality), a critical information for their effective prevention and control.AimWe aimed to provide an overview of methods to define RSV seasonality and identify factors supporting method choice or interpretation/comparison of seasonal estimates.MethodsWe systematically searched PubMed and Embase (2016-2021) for studies using quantitative approaches to determine the start and end of RSV epidemics. Studies' features (data-collection purpose, location, regional/(sub)national scope), methods, and assessment characteristics (case definitions, sampled population's age, in/outpatient status, setting, diagnostics) were extracted. Methods were categorised by their need of a denominator (i.e. numbers of specimens tested) and their retrospective vs real-time application. Factors worth considering when choosing methods and assessing seasonal estimates were sought by analysing studies.ResultsWe included 32 articles presenting 49 seasonality estimates (18 thereof through the 10% positivity threshold method). Methods were classified into eight categories, two requiring a denominator (1 retrospective; 1 real-time) and six not (3 retrospective; 3 real-time). A wide range of assessment characteristics was observed. Several studies showed that seasonality estimates varied when methods differed, or data with dissimilar assessment characteristics were employed. Five factors (comprising study purpose, application time, assessment characteristics, healthcare system and policies, and context) were identified that could support method choice and result interpretation.ConclusionMethods and assessment characteristics used to define RSV seasonality are heterogeneous. Our categorisation of methods and proposed framework of factors may assist in choosing RSV seasonality methods and interpretating results.

Influenza in Children and Adolescents: Epidemiology, Management, and Prevention

EDUCATION GAP

Influenza is among the most common infectious causes of pediatric emergency department visits and hospitalizations. Clinicians should use evidence-based guidelines to learn how to identify, manage, prevent, and treat influenza cases. Disease caused by influenza virus can be mitigated with appropriate treatment and prevention efforts.

OBJECTIVES After completing this article, readers should be able to:

1. Describe the virology and epidemiology of influenza.

2. List the clinical features and complications of influenza infections.

3. List the benefits and limitations of testing modalities for the diagnosis of influenza.

4. Appropriately apply American Academy of Pediatrics, Infectious Diseases Society of America, and Centers for Disease Control and Prevention (CDC) treatment guidelines for influenza or suspected influenza.

5. Describe the importance of influenza vaccination.

Diagnostic Accuracy of an At-Home, Rapid Self-test for Influenza: Prospective Comparative Accuracy Study

Background

Rapid diagnostic tests (RDTs) for influenza used by individuals at home could potentially expand access to testing and reduce the impact of influenza on health systems. Improving access to testing could lead to earlier diagnosis following symptom onset, allowing more rapid interventions for those who test positive, including behavioral changes to minimize spread. However, the accuracy of RDTs for influenza has not been determined in self-testing populations.

Objective

This study aims to assess the accuracy of an influenza RDT conducted at home by lay users with acute respiratory illness compared with that of a self-collected sample by the same individual mailed to a laboratory for reference testing.

Methods

We conducted a comparative accuracy study of an at-home influenza RDT (Ellume) in a convenience sample of individuals experiencing acute respiratory illness symptoms. Participants were enrolled in February and March 2020 from the Greater Seattle region in Washington, United States. Participants were mailed the influenza RDT and reference sample collection materials, which they completed and returned for quantitative reverse-transcription polymerase chain reaction influenza testing in a central laboratory. We explored the impact of age, influenza type, duration, and severity of symptoms on RDT accuracy and on cycle threshold for influenza virus and ribonuclease P, a marker of human DNA.

Results

A total of 605 participants completed all study steps and were included in our analysis, of whom 87 (14.4%) tested positive for influenza by quantitative reverse-transcription polymerase chain reaction (70/87, 80% for influenza A and 17/87, 20% for influenza B). The overall sensitivity and specificity of the RDT compared with the reference test were 61% (95% CI 50%-71%) and 95% (95% CI 93%-97%), respectively. Among individuals with symptom onset ≤72 hours, sensitivity was 63% (95% CI 48%-76%) and specificity was 94% (95% CI 91%-97%), whereas, for those with duration >72 hours, sensitivity and specificity were 58% (95% CI 41%-74%) and 96% (95% CI 93%-98%), respectively. Viral load on reference swabs was negatively correlated with symptom onset, and quantities of the endogenous marker gene ribonuclease P did not differ among reference standard positive and negative groups, age groups, or influenza subtypes. The RDT did not have higher sensitivity or specificity among those who reported more severe illnesses.

Conclusions

The sensitivity and specificity of the self-test were comparable with those of influenza RDTs used in clinical settings. False-negative self-test results were more common when the test was used after 72 hours of symptom onset but were not related to inadequate swab collection or severity of illness. Therefore, the deployment of home tests may provide a valuable tool to support the management of influenza and other respiratory infections.

Novel point-of-care biomarker combination tests to differentiate acute bacterial from viral respiratory tract infections to guide antibiotic prescribing: a systematic review

BACKGROUND

Acute respiratory tract infections (RTIs) are the most common reason to seek medical care, with many patients receiving inappropriate antibiotics. Novel testing approaches to identify aetiology at the point-of-care are required to accurately guide antibiotic treatment.

OBJECTIVE

To assess the diagnostic accuracy of biomarker combinations to rapidly differentiate between acute bacterial or viral RTI aetiology.

DATA SOURCES

MEDLINE, Embase and Web of Science databases were searched to February 2021.

STUDY ELIGIBILITY CRITERIA

Diagnostic accuracy studies comparing accuracy of point-of-care and rapid diagnostic tests in primary or secondary care, consisting of biomarker combinations, to identify bacterial or viral aetiology of RTI.

METHODS

Risk of bias was assessed using the QUADAS-2 tool. Sensitivity and specificity of tests reported by more than one study were meta-analysed using a random effects model.

RESULTS

Twenty observational studies (3514 patients) were identified. Eighteen were judged at high risk of bias. For bacterial aetiologies, sensitivity ranged from 61% to 100% and specificity from 18% to 96%. For viral aetiologies, sensitivity ranged from 59% to 97% and specificity from 74% to 100%. Studies evaluating two commercial tests were meta-analysed. For ImmunoXpert, the summary sensitivity and specificity were 85% (95% CI 75%-91%, k = 4) and 86% (95% CI 73%-93%, k = 4) for bacterial infections, and 90% (95% CI 79%-96%, k = 3) and 92% (95% CI 83%-96%, k = 3) for viral infections, respectively. FebriDx had pooled sensitivity and specificity of 84% (95% CI 75%-90%, k = 4) and 93% (95% CI 90%-95%, k = 4) for bacterial infections, and 87% (95% CI 72%-95%; k = 4) and 82% (95% CI 66%-86%, k = 4) for viral infections, respectively.

CONCLUSION

Combinations of biomarkers show potential clinical utility in discriminating the aetiology of RTIs. However, the limitations in the evidence base, due to a high proportion of studies with high risk of bias, preclude firm conclusions. Future research should be in primary care and evaluate patient outcomes and cost-effectiveness with experimental study designs.

CLINICAL TRIAL

PROSPERO registration number: CRD42020178973.

Performance of BioFire array or QuickVue influenza A + B test versus a validation qPCR assay for detection of influenza A during a volunteer A/California/2009/H1N1 challenge study

Background

Influenza places a significant burden on global health and economics. Individual case management and public health efforts to mitigate the spread of influenza are both strongly impacted by our ability to accurately and efficiently detect influenza viruses in clinical samples. Therefore, it is important to understand the performance characteristics of available assays to detect influenza in a variety of settings. We provide the first report of relative performance between two products marketed to streamline detection of influenza virus in the context of a highly controlled volunteer influenza challenge study.

Methods

Nasopharyngeal swab samples were collected during a controlled A/California/2009/H1N1 influenza challenge study and analyzed for detection of virus shedding using a validated qRT-PCR (qPCR) assay, a sample-to-answer qRT-PCR device (BioMerieux BioFire FilmArray RP), and an immunoassay based rapid test kit (Quidel QuickVue Influenza A + B Test).

Results

Relative to qPCR, the sensitivity and specificity of the BioFire assay was 72.1% [63.7–79.5%, 95% confidence interval (CI)] and 93.5% (89.3–96.4%, 95% CI) respectively. For the QuickVue rapid test the sensitivity was 8.5% (4.8–13.7%, 95% CI) and specificity was 99.2% (95.6–100%, 95% CI).

Conclusion

Relative to qPCR, the BioFire assay had superior performance compared to rapid test in the context of a controlled influenza challenge study.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-021-01516-0.

Laboratory evaluation of two point-of-care detection systems for early and accurate detection of influenza viruses in the Lao People's Democratic Republic

BACKGROUND

We evaluated molecular-based point-of-care influenza virus detection systems in a laboratory prior to a field evaluation of on-site specimen testing.

METHODS

The performance characteristics of 1) insulated isothermal polymerase chain reaction (PCR) on a POCKIT™ device and 2) real-time reverse transcription-PCR (rRT-PCR) on a MyGo Mini™ device were evaluated using human clinical specimens, beta-propiolactone-inactivated influenza viruses, and RNA controls. The rRT-PCR carried out on a CXF-96™ real-time detection system was used as a gold standard for comparison.

RESULTS

Both systems demonstrated 100% sensitivity and specificity and test results were in 100% agreement with the gold standard. POCKIT™ only correctly identified influenza A (M gene) in clinical specimens due to the unavailability of typing and subtyping reagents for human influenza viruses, while MyGo Mini™ had either a one log higher or the same sensitivity in detecting influenza viruses in clinical specimens compared to the gold standard. For inactivated viruses and/or viral RNA, the analytic sensitivity of POCKIT™ was shown to be comparable to, or more sensitive, than the gold standard. The analytic sensitivity of MyGo Mini™ had mixed results depending on the types and subtypes of influenza viruses.

CONCLUSIONS

The performance of the two systems in a laboratory is promising and supports further evaluation in field settings.

Influenza Screening via Deep Learning Using a Combination of Epidemiological and Patient-Generated Health Data: Development and Validation Study

Background

Screening for influenza in primary care is challenging due to the low sensitivity of rapid antigen tests and the lack of proper screening tests.

Objective

The aim of this study was to develop a machine learning–based screening tool using patient-generated health data (PGHD) obtained from a mobile health (mHealth) app.

Methods

We trained a deep learning model based on a gated recurrent unit to screen influenza using PGHD, including each patient’s fever pattern and drug administration records. We used meteorological data and app-based surveillance of the weekly number of patients with influenza. We defined a single episode as the set of consecutive days, including the day the user was diagnosed with influenza or another disease. Any record a user entered 24 hours after his or her last record was considered to be the start of a new episode. Each episode contained data on the user’s age, gender, weight, and at least one body temperature record. The total number of episodes was 6657. Of these, there were 3326 episodes within which influenza was diagnosed. We divided these episodes into 80% training sets (2664/3330) and 20% test sets (666/3330). A 5-fold cross-validation was used on the training set.

Results

We achieved reliable performance with an accuracy of 82%, a sensitivity of 84%, and a specificity of 80% in the test set. After the effect of each input variable was evaluated, app-based surveillance was observed to be the most influential variable. The correlation between the duration of input data and performance was not statistically significant (P=.09).

Conclusions

These findings suggest that PGHD from an mHealth app could be a complementary tool for influenza screening. In addition, PGHD, along with traditional clinical data, could be used to improve health conditions.

Impact of Rapid On-demand Molecular Diagnosis of Pediatric Seasonal Influenza on Laboratory Workflow and Testing Costs: A Retrospective Study

BACKGROUND

Seasonal influenza imposes a considerable burden worldwide. We aimed to evaluate impact of rapid pediatric seasonal influenza diagnosis on laboratory workflow and cost using a rapid antigen detection-based test combined with either a reverse transcriptase polymerase chain reaction (RT-PCR) or the Alere i Influenza A and B (Alere i) assay for confirmation of negative results as well as single Alere i testing on nasopharyngeal aspirates. A secondary objective was assessing performance of Alere i against RT-PCR.

METHODS

Effects of implementing the 3 diagnostic algorithms were assessed in the Emergency Department of Hospital Sant Joan de Déu (Barcelona, Spain) across the 2014-2015, 2015-2016 and 2016-2017 influenza seasons. Alere i performance against RT-PCR was determined during the 2015-2016 epidemic period.

RESULTS

Median time to result decreased when using Alere i as a confirmatory test of previous antigen detection and RT-PCR results or alone (9.7vs. 3.5/2.0 and 0.7 hours, P < 0.001) along with mean testing costs (&OV0556;87.3 vs. &OV0556;38.2 and &OV0556;25.0, P < 0.001). Results available before patient discharge from the emergency department increased from 42.7% for sequential testing by antigen detection and RT-PCR to 80.0% when Alere i was utilized as a stand-alone test. Alere i sensitivity and specificity values were 96.6% (95% confidence interval: 82.8%-99.4%) and 94.4% (95% confidence interval: 86.6%-97.8%), respectively.

CONCLUSIONS

Rapid Alere i testing facilitated efficient laboratory workflow near the patient during influenza epidemics while contributing cost savings when compared with serial testing by antigen and RT-PCR assays.

Clinical Practice Guidelines by the Infectious Diseases Society of America: 2018 Update on Diagnosis, Treatment, Chemoprophylaxis, and Institutional Outbreak Management of Seasonal Influenzaa

These clinical practice guidelines are an update of the guidelines published by the Infectious Diseases Society of America (IDSA) in 2009, prior to the 2009 H1N1 influenza pandemic. This document addresses new information regarding diagnostic testing, treatment and chemoprophylaxis with antiviral medications, and issues related to institutional outbreak management for seasonal influenza. It is intended for use by primary care clinicians, obstetricians, emergency medicine providers, hospitalists, laboratorians, and infectious disease specialists, as well as other clinicians managing patients with suspected or laboratory-confirmed influenza. The guidelines consider the care of children and adults, including special populations such as pregnant and postpartum women and immunocompromised patients.

Clinical Practice Guidelines by the Infectious Diseases Society of America: 2018 Update on Diagnosis, Treatment, Chemoprophylaxis, and Institutional Outbreak Management of Seasonal Influenzaa

These clinical practice guidelines are an update of the guidelines published by the Infectious Diseases Society of America (IDSA) in 2009, prior to the 2009 H1N1 influenza pandemic. This document addresses new information regarding diagnostic testing, treatment and chemoprophylaxis with antiviral medications, and issues related to institutional outbreak management for seasonal influenza. It is intended for use by primary care clinicians, obstetricians, emergency medicine providers, hospitalists, laboratorians, and infectious disease specialists, as well as other clinicians managing patients with suspected or laboratory-confirmed influenza. The guidelines consider the care of children and adults, including special populations such as pregnant and postpartum women and immunocompromised patients.

Effect of rapid influenza diagnostic tests on patient management in an emergency department

Objective

We evaluated the effect of rapid influenza diagnostic tests (RIDTs) on patient management in an emergency department for 3 years after 2009, and also identified factors associated with the choice of treatment for patients with influenza-like illnesses.

Methods

The study period consisted of three influenza epidemic seasons. Patients older than 15 years who underwent RIDTs in the emergency department and were then discharged without admission were included.

Results

A total of 453 patients were enrolled, 114 of whom had positive RIDT results and 339 had negative results. Antiviral medication was prescribed to 103 patients (90.4%) who had positive RIDT results, while 1 patient (0.3%) who tested negative was treated with antivirals (P<0.001). Conservative care was administered to 11 RIDT-positive patients (9.6%) and 244 RIDT-negative patients (72.0%) (P<0.001). Symptom onset in less than 48 hours, being older than 65 years, and the presence of comorbidities were not associated with the administration of antiviral therapy.

Conclusion

RIDT results had a critical effect on physician decision-making regarding antiviral treatment for patients with influenza-like illnesses in the emergency department. However, symptom onset in less than 48 hours, old age, and comorbidities, which are all indications for antiviral therapy, were not found to influence the administration of antiviral treatment.

Microbiological Diagnosis of Respiratory Illness

A wide variety of microorganisms are potential respiratory pathogens, and the spectrum of known pathogens for each respiratory infection syndrome has not changed markers over recent years. Detection of likely etiologic agents of respiratory infections can help direct management and can also play an important role in disease surveillance. For this purpose, we are still reliant on many traditional diagnostic tools that have been used for decades in order to determine the microbial etiology of respiratory infections. However, these tools have been increasingly supplemented by newer methods, particular molecular diagnostic techniques, which have enabled the more rapid detection of many pathogens that were previously difficult to detect. These advances have particularly lead to improvements in the ability to detect respiratory viruses and also other microorganisms that do not normally colonize the respiratory tract. Recognition of the existence of the lung microbiome has challenged the traditional views of pneumonia pathogenesis and may provide the opportunity for new diagnostic tools that are focused on more than just detection of specific known pathogens. Continued liaison between clinicians and laboratory staff is vital in order to facilitate the most cost-effective use of laboratory diagnostics.

Immunogenicity and safety of a Trivalent Influenza HA vaccine in Indonesian infants and children

INTRODUCTION

High rate of influenza infection in children made influenza vaccination strongly recommended for all person aged >6 months in Indonesia. Bio Farma Trivalent Influenza HA (Flubio®) vaccine has been used in adolescents and adults, resulted in increased seroconversion, seroprotection rates and geometric mean titer (GMT). However, no data is available regarding its efficacy and safety in children. This study aimed to assess the immunogenicity and safety of Flubio® vaccine in infants and children.

MATERIALS AND METHODS

This was a phase II, open-labeled, clinical trial conducted on healthy children aged 6 month-11 years, vaccinated with 1 or 2 doses of Influenza HA vaccine, with a 28-day interval. Flubio® vaccine composed of A/California/7/2009 (H1N1) pandemic 09, A/Texas/50/2012 (H3N2), and B/Massachusetts/2/2012 strain. This study was held at East Jakarta, Indonesia from May until July 2014. A Total of 405 subjects were included and divided into three groups: A(6-35 months), B(3-8 years), and C(9-11 years). Antibody titer was measured at visit V1 (Day 0), V2 (28 days/+7days after the first dose) and V3 (28 days/+7days after second dose). The seroprotection and seroconversion rates were assessed. Safety was assessed up to 28 days following each dose.

RESULTS

A total of 404 subjects completed the study. After vaccination, all subjects achieved seroprotection and increased seroconversion rates, with post-vaccination antibody titer of ≥1:40 HI for all strains. The GMT also increased significantly. Within 30 min after vaccination, 14.6% and 2% had local and systemic reactions; meanwhile, between 30 min to 72 h after vaccination, 35.1% and 13.6% subjects had local and systemic reactions, respectively. Most reactions were mild. No serious adverse event (SAE) was reported related to vaccine.

CONCLUSION

Flubio® (Influenza HA Trivalent) vaccine is immunogenic and safe for children aged 6 months-11 years.

TRIAL REGISTRATION

The trial is registered at the US National Institutes of Health (ClinicalTrials.gov) #NCT02093260.

Evaluating oseltamivir prescriptions in Centers for Medicare and Medicaid Services medical claims records as an indicator of seasonal influenza in the United States

Background

Over 34 million residents of the United States aged 65 years and older are also Medicare prescription drug beneficiaries. Medical claims records for this age group potentially provide a wealth of data for better understanding influenza epidemiology.

Objective

The purpose of this study was to evaluate data on oseltamivir dispensing extracted from medical claims records as an indicator of influenza activity in the United States for the 2010‐11 through 2014‐15 influenza seasons.

Methods

We used Centers for Medicare and Medicaid Services (CMS) medical claims data to evaluate the weekly number of therapeutic oseltamivir prescriptions dispensed following a rapid influenza diagnostic test among beneficiaries 65 years old and older as an indicator of influenza timing and intensity. We compared the temporal changes in this indicator to changes in the proportion of influenza‐like illnesses among outpatient visits in the US Outpatient Influenza‐like Illness Surveillance Network (ILINet) by administrative regions defined by the US Department of Health and Human Services. Using the moving epidemic method, we determined intensity thresholds and categorized the severity of seasons for both CMS and ILINet data.

Results

Centers for Medicare and Medicaid Services oseltamivir data and ILINet data were strongly correlated by administrative region (median Spearman's ρ = 0.78; interquartile range = 0.73‐0.80). CMS oseltamivir data and ILINet data substantially agreed (Cohen's weighted κ = 0.62) as to the seasonal severity across administrative regions.

Conclusions

Our results support the use of oseltamivir dispensing in medical claims data as an indicator of US influenza activity.

Respiratory RNA Viruses

Acute upper and lower respiratory infections are a major public health problem and a leading cause of morbidity and mortality worldwide. At greatest risk are young children, the elderly, the chronically ill, and those with suppressed or compromised immune systems. Viruses are the predominant cause of respiratory tract illnesses and include RNA viruses such as respiratory syncytial virus, influenza virus, parainfluenza virus, metapneumovirus, rhinovirus, and coronavirus. Laboratory testing is required for a reliable diagnosis of viral respiratory infections, as a clinical diagnosis can be difficult since signs and symptoms are often overlapping and not specific for any one virus. Recent advances in technology have resulted in the development of newer diagnostic assays that offer great promise for rapid and accurate detection of respiratory viral infections. This chapter emphasizes the fundamental characteristics and clinical importance of the various RNA viruses that cause upper and lower respiratory tract diseases in the immunocompromised host. It highlights the laboratory methods that can be used to make a rapid and definitive diagnosis for the greatest impact on the care and management of ill patients, and the prevention and control of hospital-acquired infections and community outbreaks.

Evaluation of the point-of-care Becton Dickinson Veritor™ Rapid influenza diagnostic test in Kenya, 2013-2014

BACKGROUND

We evaluated the performance of the Becton Dickinson Veritor™ System Flu A + B rapid influenza diagnostic test (RIDT) to detect influenza viruses in respiratory specimens from patients enrolled at five surveillance sites in Kenya, a tropical country where influenza seasonality is variable.

METHODS

Nasal swab (NS) and nasopharyngeal (NP)/oropharyngeal (OP) swabs were collected from patients with influenza like illness and/or severe acute respiratory infection. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the RIDT using NS specimens were evaluated against nasal swabs tested by real time reverse transcription polymerase chain reaction (rRT-PCR). The performance parameter results were expressed as 95% confidence intervals (CI) calculated using binomial exact methods, with P < 0.05 considered significant. Two-sample Z tests were used to test for differences in sample proportions. Analysis was performed using SAS software version 9.3.

RESULTS

From July 2013 to July 2014, 3,569 patients were recruited, of which 78.7% were aged <5 years. Overall, 14.4% of NS specimens were influenza-positive by RIDT. RIDT overall sensitivity was 77.1% (95% CI 72.8-81.0%) and specificity was 94.9% (95% CI 94.0-95.7%) compared to rRT-PCR using NS specimens. RIDT sensitivity for influenza A virus compared to rRT-PCR using NS specimens was 71.8% (95% CI 66.7-76.4%) and was significantly higher than for influenza B which was 43.8% (95% CI 33.8-54.2%). PPV ranged from 30%-80% depending on background prevalence of influenza.

CONCLUSION

Although the variable seasonality of influenza in tropical Africa presents unique challenges, RIDTs may have a role in making influenza surveillance sustainable in more remote areas of Africa, where laboratory capacity is limited.

Finnish guidelines for the treatment of laryngitis, wheezing bronchitis and bronchiolitis in children

Evidence-based guidelines are needed to harmonise and improve the diagnostics and treatment of children's lower respiratory tract infections. Following a professional literature search, an interdisciplinary working group evaluated and graded the available evidence and constructed guidelines for treating laryngitis, bronchitis, wheezing bronchitis and bronchiolitis.

CONCLUSION

Currently available drugs were not effective in relieving cough symptoms. Salbutamol inhalations could relieve the symptoms of wheezing bronchitis and should be administered via a holding chamber. Nebulised adrenaline or inhaled or oral glucocorticoids did not reduce hospitalisation rates or relieve symptoms in infants with bronchiolitis and should not be routinely used.

Performance of rapid influenza diagnostic tests (QuickVue) for influenza A and B Infection in India

BACKGROUND

Rapid point-of-care (POC) tests provide an economical alternative for rapid diagnosis and treatment of influenza, especially in public health emergency situations.

OBJECTIVES

To test the performance of a rapid influenza diagnostic test, QuickVue (Quidel) as a POC test against a real-time polymerase chain reaction (RT-PCR) assay for detection of influenza A and B in a developing country setting.

STUDY DESIGN

In a prospective observational design, 600 patients with influenza-like illness (ILI) or with severe acute respiratory illness (SARI) who were referred to the Influenza Clinic of a tertiary care hospital in Srinagar, India from September 2012 to April 2013, were enrolled for diagnostic testing for influenza using QuickVue or RT-PCR. All influenza A-positive patients by RT-PCR were further subtyped using primers and probes for A/H1pdm09 and A/H3.

RESULTS

Of the 600 patients, 186 tested positive for influenza A or B by RT-PCR (90 A/H1N1pdm09, 7 A/H3 and 89 influenza B), whereas only 43 tested positive for influenza (influenza A=22 and influenza B=21) by QuickVue. Thus, the sensitivity of the QuickVue was only 23% (95% confidence interval, CI: 17.3-29.8) and specificity was 100% (95% CI: 99.1-100) with a positive predictive value (PPV) of 100% (95% CI 91.8-100) and a negative predictive value (NPV) of 74.3% (95% CI: 70.5-77.9) as compared to RT-PCR.

CONCLUSIONS

The high specificity of QuickVue suggest that this POC test can be a useful tool for patient management or triaging during a public health crisis but a low sensitivity suggests that a negative test result need to be further tested using RT-PCR.

Common childhood viral infections

Infections caused by viruses are universal during childhood and adolescence. Clinicians will regularly care for children and adolescents who present with infections caused by a wide number of viral pathogens. These infections have varied presentations. Many infections may have clinical presentations that are specific to the infecting virus but present differently, based on the age and immunocompetence of the patient. Some children are directly impacted early in their lives when maternal disease results in an in utero infection (cytomegalovirus, rubella virus, or parvovirus B19). Other viruses may infect children in a predictable pattern as they grow older (rhinovirus or influenza virus). Fortunately, many viral infections frequently encountered in the past are no longer extant due to widespread immunization efforts. Recognition of these vaccine-preventable infections is important because outbreaks of some of these diseases (mumps or measles) continue to occur in the United States. Vigilance in vaccine programs against these viral agents can prevent their re-emergence. In addition, an increasing number of viral infections (herpes simplex virus, influenza virus, varicella zoster virus, or cytomegalovirus) can now be successfully treated with antiviral medications. Most viral infections in children result in self-limited illness and are treated symptomatically and infected children experience full recovery. This review will address the epidemiology, clinical presentation, diagnosis, treatment, and prevention of viral infections commonly encountered by the clinician.

Factors affecting the success of influenza laboratory diagnosis

Influenza is one of the most common human infectious diseases, and has profound health and economic consequences. The laboratory diag- nosis of influenza virus infections plays an important role in the global surveillance of influenza. Therefore, there is a growing demand for highly sensitive and rapid methods for detecting influenza. The performance of particular diagnostic methods is affected by various factors. In this study, we assess the effects of patients' age and time to diagnosis on the probability of detecting influenza using four diagnostic methods (virus isolation, rapid test, RT-PCR and real-time RT-PCR). We examined 3,546 samples from central and eastern Slovakia during the influenza seasons from 2005-2006 to 2010-2011. In general, the probability of influenza detection significantly decreased with the time from onset of illness to sample collection (T1) as well as with patients' age (AGE). On the contrary, time from sample collection to delivery (T2) did not play a role in the prob- ability of influenza detection. As judged by odds ratios, the virus isolation method was most sensitive to T1, followed by the rapid test and RT-PCR methods. For the effect of AGE, the rapid test and virus isolation methods were more sensitive than PCR-based methods. The effects of T1 and AGE were independent of each other. Laboratories which participate in inifluenza surveillance should use several methods to enable rapid and accurate influenza A and B virus detection.

Quantitative influenza follow-up testing (QIFT)--a novel biomarker for the monitoring of disease activity at the point-of-care

BACKGROUND

Influenza infections induce considerable disease burden in young children. Biomarkers for the monitoring of disease activity at the point-of-care (POC) are currently lacking. Recent methodologies for fluorescence-based rapid testing have been developed to provide improved sensitivities with the initial diagnosis. The present study aims to explore the utility of second-generation rapid testing during longitudinal follow-up of influenza patients (Rapid Influenza Follow-up Testing = RIFT). Signal/control fluorescent readouts (Quantitative Influenza Follow-up Testing = QIFT) are evaluated as a potential biomarker for the monitoring of disease activity at the POC.

METHODS AND FINDINGS

RIFT (SOFIA) and QIFT were performed at the POC and compared to blinded RT-PCR at the National Reference Centre for Influenza. From 10/2011-4/2013, a total of 2048 paediatric cases were studied prospectively; 273 cases were PCR-confirmed for influenza. During follow-up, RIFT results turned negative either prior to PCR (68%), or simultaneously (30%). The first negative RIFT occurred after a median of 8 days with a median virus load (VL) of 5.6×10∧3 copies/ml and cycle threshold of 37, with no evidence of viral rebound. Binning analysis revealed that QIFT differentiated accurately between patients with low, medium and high viral titres. QIFT increase/decrease showed 88% agreement (sensitivity = 52%, specificity = 95%) with VL increase/decrease, respectively. QIFT-based viral clearance estimates showed similar values compared to PCR-based estimates. Variations in viral clearance rates were lower in treated compared to untreated patients. The study was limited by use of non-invasive, semi-quantitative nasopharyngeal samples. VL measurements below the limit of detection could not be quantified reliably.

CONCLUSIONS

During follow-up, RIFT provides a first surrogate measure for influenza disease activity. A "switch" from positive to negative values may indicate a drop in viral load below a critical threshold, where rebound is no longer expected. QIFT may provide a useful tool for the monitoring of disease burden and viral clearance at the POC.

Performance of a rapid multi-analyte 2-photon excitation assay in children with acute respiratory infection

The purpose of this study is to evaluate the diagnostic performance of the novel 2-photon excitation-based mariPOC© Assay (ArcDia Laboratories, Turku, Finland) for antigen detection of respiratory viruses versus real-time polymerase chain reaction (PCR). The mariPOC Assay and 2 multiplex real-time PCR techniques were performed on nasopharyngeal samples from pediatric patients with suspicion of acute respiratory infection admitted to a children's hospital in Spain during October 2011 to January 2013. A total of 233 samples were studied. Sensitivities and specificities (95% confidence interval) of the mariPOC Assay were for respiratory syncytial virus (RSV), 78.4% (69.7-85.6) and 99.2% (96.3-100.0); influenza virus (IFV) A, 66.7% (26.2-94.0) and 99.6% (97.9-100.0); IFV-B, 63.6% (33.6-87.2) and 100.0% (98.7-100.0); human metapneumovirus (hMPV), 60.0% (34.5-81.9) and 100.0% (98.6-100.0); adenovirus (ADV), 12.5% (0.6-48.0) and 100.0% (98.7-100.0), respectively. The mariPOC Assay is a highly specific method for simultaneous detection of 8 respiratory viruses but has sensitivities that range from moderately high for RSV to moderate for IFV and hMPV and low for ADV.

Burden of pediatric influenza A virus infection post swine-flu H1N1 pandemic in Egypt

OBJECTIVE

To screen children with influenza like illness or with symptoms of acute respiratory tract infections for influenza A virus infection - post swine flu pandemic era - using rapid influenza diagnostic tests.

METHODS

During two years (2010 & 2011), 1 200 children with influenza like illness or acute respiratory tract infections (according to World Health Organization criteria) were recruited. Their ages ranged from 2-60 months. Nasopharyngeal aspirates specimens were collected from all children for rapid influenza A diagnostic test.

RESULTS

Influenza A virus rapid test was positive in 47.5% of the children; the majority (89.6%) were presented with lower respiratory tract infections. Respiratory rate and temperature were significantly higher among positive rapid influenza test patients.

CONCLUSIONS

Influenza A virus infection is still a major cause of respiratory tract infections in Egyptian children. It should be considered in all cases with cough and febrile episodes and influenza like symptoms even post swine flu pandemic.

Sensitivity and specificity of in vitro diagnostic device used for influenza rapid test in Taiwan

The pandemic influenza A/H1N1 outbreak resulted in 18,449 deaths in over 214 countries. In Taiwan, the influenza rapid test, an in vitro diagnostic device (Flu-IVD), only requires documented reviews for market approval by the Taiwan Food and Drug Administration. The purpose of this study was to investigate the analytical sensitivity and specificity of Flu-IVDs used in Taiwan. Analytical sensitivity and specificity tests were performed for influenza antigens A/California/7/2009 (H1N1) virus, A/Victoria/210/2009 (H3N2) virus, B/ Brisbane/60/08 virus, and human coronavirus OC43. A total of seven domestic and 31 imported Flu-IVD samples were collected, of which, 20 samples had inadequate labeling, including those with removed package inserts or incorrect insert information. The analytical sensitivity of Flu-IVDs for A/H1N1, A/H3N2, and Flu B was 500-1000 ng/mL, 1000 ng/mL, and 1000 ng/mL, respectively. For the 50% cell culture infective dose (CCID50) label, the average A/H1N1 and A/H3N2 sensitivity for Flu-IVDs was log10 5.8 ± 0.5 and log10 6.6 ± 0.5 CCID50/mL, respectively. As to the specificity test, no product cross-reacted with human coronavirus OC43. This study provides important information on the Flu-IVD regulation status and can thus help the government formulate policies for the regulation of in vitro diagnostic devices in Taiwan.

Influenza testing, diagnosis, and treatment in the emergency department in 2009-2010 and 2010-2011

OBJECTIVES

The objective was to describe patterns of rapid influenza test ordering, diagnosis of influenza, and antiviral prescribing by the treating physician for children and adults presenting to emergency departments (EDs) with fever and acute respiratory symptoms in Winston-Salem, North Carolina, over two influenza seasons.

METHODS

The authors prospectively enrolled patients presenting to the ED with fever and acute respiratory symptoms for two influenza seasons: H1N1 pandemic of September 2009 through mid-May 2010 and November 2010 through April 2011. Enrolled patients had nose or and throat swabs obtained and tested for influenza by viral culture and polymerase chain reaction (PCR) testing. Demographic information and medical history were obtained by patient or guardian report. Testing, treatment, and discharge diagnosis from the ED visit, as well as medical history and insurance status, were ascertained from chart review.

RESULTS

Among 2,293 eligible patients approached, 1,657 (72%) were enrolled, of whom 38% were younger than 18 years, 47% were 18 to 49 years, and 15% were 50 years of age and older. Overall, 14% had culture- or PCR-confirmed influenza. The odds of 1) rapid influenza test ordering, 2) a physician diagnosis of influenza, and 3) prescribing antiviral treatment during the ED visit were fourfold higher among patients with than without culture- or PCR-confirmed influenza. The odds of rapid influenza test ordering were threefold lower in 2009/2010 than 2010/2011, whereas the odds of physician diagnosis of influenza and antiviral prescriptions were 2- and 3.5-fold higher, respectively.

CONCLUSIONS

In 2009/2010 compared to 2010/2011, the odds of rapid influenza test ordering were lower, whereas the odds of influenza-specific discharge diagnoses and antiviral prescriptions were higher among patients presenting to the ED with culture/PCR-confirmed influenza. These results demonstrated a gap between clinical practice and recommendations for the diagnosis and treatment of influenza from the Centers for Disease Control and Prevention (CDC).

Potentialities of aberrantly methylated circulating DNA for diagnostics and post-treatment follow-up of lung cancer patients

To date, aberrant DNA methylation has been shown to be one of the most common and early causes of malignant cell transformation and tumors of different localizations, including lung cancer. Cancer cell-specific methylated DNA has been found in the blood of cancer patients, indicating that cell-free DNA circulating in the blood (cirDNA) is a convenient tumor-associated DNA marker that can be used as a minimally invasive diagnostic test. In the current study, we investigated the methylation status in blood samples of 32 healthy donors and 60 lung cancer patients before and after treatment with neoadjuvant chemotherapy followed by total tumor resection. Using quantitative methylation-specific PCR, we found that the index of methylation (IM), calculated as IM = 100 × [copy number of methylated/(copy number of methylated + unmethylated gene)], for the RASSF1A and RARB2 genes in the cirDNA isolated from blood plasma and cell-surface-bound cirDNA was elevated 2- to 3-fold in lung cancer patients compared with healthy donors. Random forest classification tree model based on these variables combined (RARB2 and RASSF1A IM in both plasma and cell-surface-bound cirDNA) lead to NSCLC patients' and healthy subjects' differentiation with 87% sensitivity and 75% specificity. An association of increased IM values with an advanced stage of non-small-cell lung cancer was found for RARB2 but not for RASSF1A. Chemotherapy and total tumor resection resulted in a significant decrease in the IM for RARB2 and RASSF1A, in both cirDNA fractions, comparable to the IM level of healthy subjects. Importantly, a rise in the IM for RARB2 was detected in patients within the follow-up period, which manifested in disease relapse at 9 months, confirmed with instrumental and pathologic methods. Our data indicate that quantitative analysis of the methylation status of the RARB2 and RASSF1A tumor suppressor genes in both cirDNA fractions is a useful tool for lung cancer diagnostics, evaluation of cancer treatment efficiency and post-treatment monitoring.

Value of rapid antigen test for pandemic influenza A (H1N1) 2009 in the pediatric emergency department

OBJECTIVE

Pandemic H1N1 influenza is the predominant influenza virus circulating in Turkey in 2009. Because of the clinical manifestations of influenza overlap with those attributable to other common respiratory illnesses of childhood, establishing a diagnosis of influenza requires confirmatory testing. The aim of our study was to define the predictive value of rapid influenza antigen detection test in children presenting to a pediatric emergency care department with influenza-like illness and to compare with clinical signs and symptoms.

METHODS

From October to November 2009, 3646 patients presented with influenza-like illness to the pediatric emergency department. Influenza-like illness is defined as fever with cough or sore throat in the absence of a known cause other than influenza. Enrollment criteria included fever and at least one of the following symptoms: coryza, cough, headache, sore throat, or myalgia. All 322 enrolled patients received a nasal wash for rapid influenza diagnostic tests, and the results were compared with clinical signs.

RESULTS

Rapid influenza detection test result was found positive in 167 (51.9%) of 322 patients. Clinical findings included fever as the presenting complaint (100%), fever (≥38 °C) (93.4%), cough (91.3%), rhinorrhea (66.1%), sore throat (35.1%), vomiting-diarrhea (22.4%), myalgia (20.2%), headache (18%) and shortness of breath (12.1%). There were 211 patients (65.5%) at high risk for the development of complications of pandemic H1N1 influenza A such as chronic lung disease (asthma) (n = 103, 48.8%), age younger than 2 years (n = 78, 37%), and neurologic disease (n = 10, 4.7%). The positivity rate and sensitivity of the test increase up to 70% in patients, who had the high body temperature (≥39 °C). The rapid test achieved the highest sensitivity in patients, who have high fever (≥39 °C), myalgia, vomiting, and diarrhea.

CONCLUSIONS

We found that if the patients have high fever (≥39 °C), myalgia, and vomiting-diarrhea together, the likelihood of rapid antigen test positivity rate increases in patients, who presented with influenza-like illness.

Point-of-Care Testing as an Influenza Surveillance Tool: Methodology and Lessons Learned from Implementation

Objectives. Disease surveillance combines data collection and analysis with dissemination of findings to decision makers. The timeliness of these activities affects the ability to implement preventive measures. Influenza surveillance has traditionally been hampered by delays in both data collection and dissemination. Methods. We used statistical process control (SPC) to evaluate the daily percentage of outpatient visits with a positive point-of-care (POC) influenza test in the University of Utah Primary Care Research Network. Results. Retrospectively, POC testing generated an alert in each of 4 seasons (2004-2008, median 16 days before epidemic onset), suggesting that email notification of clinicians would be 9 days earlier than surveillance alerts posted to the Utah Department of Health website. In the 2008-09 season, the algorithm generated a real-time alert 19 days before epidemic onset. Clinicians in 4 intervention clinics received email notification of the alert within 4 days. Compared with clinicians in 6 control clinics, intervention clinicians were 40% more likely to perform rapid testing (P = 0.105) and twice as likely to vaccinate for seasonal influenza (P = 0.104) after notification. Conclusions. Email notification of SPC-generated alerts provided significantly earlier notification of the epidemic onset than traditional surveillance. Clinician preventive behavior was not significantly different in intervention clinics.

Identification of respiratory viruses with a novel point-of-care multianalyte antigen detection test in children with acute respiratory tract infection

BACKGROUND

Rapid etiological diagnosis of a respiratory virus infection may have impact on antiviral and antibiotic therapy, patient cohorting, and prediction of the clinical course. Most point-of-care tests for detection of respiratory viruses have limitations in diagnostic performance and clinical usability. A novel, multianalyte point-of-care antigen detection test system (mariPOC(®); ArcDia International Oy Ltd., Turku, Finland) detects eight respiratory viruses (influenza A and B viruses, respiratory syncytial virus (RSV), adenovirus, human metapneumovirus, and parainfluenza type 1, 2, and 3 viruses) from a single nasopharyngeal swab specimen by a fully automated, random-access immunoassay method.

OBJECTIVES

To evaluate mariPOC(®) point-of-care test system in comparison with reverse transcription polymerase chain reaction (RT-PCR) in a pediatric emergency department setting.

STUDY DESIGN

Prospectively collected samples from 158 children (mean age, 1.8 years) with respiratory symptoms and/or fever were analyzed both by mariPOC(®) and by multiplex RT-PCR.

RESULTS

The sensitivities and specificities (95% confidence intervals) of the mariPOC(®) test were for influenza A (n = 7), 71% (38-100) and 100%; influenza B (n = 22), 86% (72-100) and 98% (95-100); RSV (n = 35), 89% (78-99) and 100%; adenovirus (n = 12), 25% (1-50) and 97% (95-99); and for human metapneumovirus (n = 8), 50% (15-85) and 100%, respectively. Parainfluenzaviruses were detected only in five patients.

CONCLUSIONS

This novel point-of-care test system is a rapid, practical, and specific method for simultaneous detection of eight respiratory viruses. Compared with RT-PCR, its sensitivity is moderately high for detection of RSV and influenza viruses, and low for adenovirus.

Clinical Predictors of Influenza in Young Children: The Limitations of "Influenza-Like Illness"

BACKGROUND

Influenza-like illness (ILI) definitions have been infrequently studied in young children. Despite this, clinical definitions of ILI play an important role in influenza surveillance. This study aims to identify clinical predictors of influenza infection in children ≤5 years old from which age-specific ILI definitions are then constructed.

METHODS

Children aged 6-59 months with a history of fever and acute respiratory symptoms were recruited in the Western Australia Influenza Vaccine Effectiveness (WAIVE) Study. Clinical data and per-nasal specimens were obtained from all children. Logistic regression identified significant predictors of influenza infection. Different ILI definitions were compared for diagnostic accuracy.

RESULTS

Children were recruited from 2 winter influenza seasons (2008-2009; n = 944). Of 919 eligible children, 179 (19.5%) had laboratory-confirmed influenza infection. Predictors of infection included increasing age, lack of influenza vaccination, lower birth weight, fever, cough, and absence of wheeze. An ILI definition comprising fever ≥38°C, cough, and no wheeze had 58% sensitivity (95% confidence interval [CI], 50-66), 60% specificity (95% CI, 56-64), 26% positive predictive value (95% CI, 21-31), and 86% negative predictive value (95% CI, 82-89). The addition of other symptoms or higher fever thresholds to ILI definition had little impact. The Centers for Disease Control and Prevention definition of ILI (presence of fever [≥37.8°C] and cough and/or sore throat) was sensitive (92%; 95% CI, 86-95), yet lacked specificity (10%; 95% CI, 8-13) in this population.

CONCLUSIONS

Influenza-like illness is a poor predictor of laboratory-confirmed influenza infection in young children but can be improved using age-specific data. Incorporating age-specific ILI definitions and/or diagnostic testing into influenza surveillance systems will improve the accuracy of epidemiological data.

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.

Early detection of influenza A and B infection in infants and children using conventional and fluorescence-based rapid testing

BACKGROUND

The appropriate management of infants and children with influenza depends on the accurate and timely diagnosis, ideally at the point of care (POC).

OBJECTIVES

To evaluate the use of simultaneous RSV/influenza rapid testing with QuickVue™ test strips as well as (the use of) novel, fluorescence-based, rapid influenza antigen testing (SOFIA™) in infants and children with influenza-like illness (ILI).

STUDY DESIGN

The Study was conducted in a real-time surveillance program at the Charité Department of Pediatrics in collaboration with the National Reference Centre for Influenza at the Robert Koch Institute (RKI) in Berlin, Germany (Charité Influenza-Like Disease=ChILD Cohort).

RESULTS

During the 2010/2011 influenza season, 395 infants and children were simultaneously tested using QuickVue™ FluA&B and RSV10 rapid tests at POC compared to independent RT-PCR. Sensitivities were 62.7/67.8% for Influenza/RSV overall, but highest in infants <1 year with 76.0/76.2%. The evaluation of the fluorescence-based rapid test SOFIA™ with frozen laboratory samples (derived from the 2008/2009 and 2010/2011 national surveillance) yielded sensitivities of 97.7/86.7/86.7/81.7% for influenza A(H1N1)pdm09/A(H3N2)/B-Victoria/B-Yamagata in samples with CT values <34, and 80.2/79.8/67.5/62.5% for all CT values combined. The same method used at POC with 649 consecutive ChILD patients in 2011-2012 yielded sensitivity/specificity/PPV/NPV values of 78.9/99.7/96.6/97.3%. Again, sensitivities were highest in infants (85.7%) and small children <2 years (88%).

CONCLUSIONS

Fluorescence-based rapid antigen testing provides a highly sensitive and specific tool for POC diagnostics of acute influenza in the paediatric age group, especially in infants and small children <2 years, when viral loads are at their peak and treatment decisions are imminent.

Update on influenza diagnostics: lessons from the novel H1N1 influenza A pandemic

The menu of diagnostic tools that can be utilized to establish a diagnosis of influenza is extensive and includes classic virology techniques as well as new and emerging methods. This review of how the various existing diagnostic methods have been utilized, first in the context of a rapidly evolving outbreak of novel influenza virus and then during the different subsequent phases and waves of the pandemic, demonstrates the unique roles, advantages, and limitations of each of these methods. Rapid antigen tests were used extensively throughout the pandemic. Recognition of the low negative predictive values of these tests is important. Private laboratories with preexisting expertise, infrastructure, and resources for rapid development, validation, and implementation of laboratory-developed assays played an unprecedented role in helping to meet the diagnostic demands during the pandemic. FDA-cleared assays remain an important element of the diagnostic armamentarium during a pandemic, and a process must be developed with the FDA to allow manufacturers to modify these assays for detection of novel strains in a timely fashion. The need and role for subtyping of influenza viruses and antiviral susceptibility testing will likely depend on qualitative (circulating subtypes and their resistance patterns) and quantitative (relative prevalence) characterization of influenza viruses circulating during future epidemics and pandemics.

Diagnostic performance of the BinaxNow Influenza A&B rapid antigen test in ED patients

OBJECTIVE

The objective of this study is to evaluate the diagnostic performance of the BinaxNow Influenza A&B rapid antigen test (RAT) in emergency department (ED) patients.

METHODS

We prospectively enrolled a systematic sample of ED patients older than 6 months with acute respiratory symptoms or nonlocalizing fever during 3 consecutive influenza seasons (2008-2011). Nasal and throat swabs collected by research personnel were tested for influenza by real-time reverse transcription-polymerase chain reaction (RT-PCR). Clinicians independently ordered RATs during clinical care; these specimens were collected by clinical staff and tested for influenza using the BinaxNow RAT. Patients with both a research RT-PCR and clinical RAT were included in the study. Rapid antigen test diagnostic performance was evaluated using RT-PCR as a criterion standard, with preplanned, stratified analysis for subject age, duration of symptoms, influenza subtype, and polymerase chain reaction cycle threshold, which provides a semiquantitative estimate of viral load.

RESULTS

Of 561 subjects enrolled, 131 (23.4%) had a positive RT-PCR, and 37 (6.6%) had a positive RAT. Overall, RAT performance included sensitivity of 24.4% (95% confidence interval [CI], 17.5%-32.9%), specificity of 98.8% (95% CI, 97.1%-99.6%), positive predictive value of 86.5% (95% CI, 70.4%-94.9%), negative predictive value of 81.1% (95% CI, 77.4%-84.3%). Rapid antigen test sensitivities were low for all categories of subject age, symptom duration, influenza subtype, and cycle threshold.

CONCLUSION

The BinaxNow RAT demonstrated high specificity and poor sensitivity in ED patients selected by treating clinicians for influenza testing. A negative RAT is a poor predictor for the absence of influenza in the ED and should not be used as a criterion to withhold antiviral medications.

Viral load and clinical features in children infected with seasonal influenza B in 2006/2007

BACKGROUND/PURPOSE

In influenza B infection, viral load is believed to be related to the severity of clinical illness. The correlation between viral load and symptoms is not known. We conducted a study to assess the relationship between virus load and clinical features in children infected with influenza B, in the hope that clinical features could be used as surrogate markers of viral load to guide treatment.

METHODS

Between December 2006 and February 2007, 228 patients with fever and respiratory symptoms were prospectively enrolled in our tertiary hospital-based study. Real-time reverse transcription polymerase chain reaction (RT-PCR) was performed to determine viral load.

RESULTS

Real-time RT-PCR was positive for influenza B in 76 patients. Using virus culture as the gold standard, the sensitivity and specificity were 95% and 87%, respectively. Influenza culture positive rate significantly correlated with viral load (p = 0.03). The median copy number of influenza B virus in the 76 RT-PCR positive patients was 9735 copies/ml (range 4.8×10¹-2.0×10⁶ copies/ml). Samples obtained later in the clinical course tended to have lower viral load (p = 0.7), while patient age (p = 0.72) and fever duration (p = 0.96) positively related to viral load. In patients >3 years of age, myalgia was related to statistically lower viral loads (14300 vs. 1180; p = 0.025). Patients with chills tended to have higher viral loads (72450 vs. 7640; p = 0.1). Patients with abdominal pain tended to have lower viral loads (1998 vs. 12550; p = 0.06).

CONCLUSION

Culture rate positively correlated with viral load. Patients with myalgia had a lower viral load.

A scoring system for predicting results of influenza rapid test in children: a possible model facing overwhelming pandemic infection

Background

The pandemic novel influenza H1N1 (swine) influenza A virus (H1N1v) infection has caused large-scale community infection in Taiwan. Anxiety developed in the general public and physicians faced a huge challenge in many aspects. We conducted this prospective study to develop a scoring system based on the clinical manifestations for predicting the results of influenza rapid testing, as a surrogate of influenza rapid testing, to lower the anxiety and decrease the burden for the test.

Methods

From September 1, 2009 to October 5, 2009, pediatric patients who received influenza rapid tests were enrolled, and questionnaires were recorded and analyzed in the first 2 weeks. A further scoring system was conducted to predict the results of influenza rapid tests and validated in the next 3 weeks.

Results

Eight hundred and forty-five children were enrolled in our study. In the first phase, data from 506 patients showed that those with age ≥ 5 years, fever ≥ 38°C, contact history of influenza A infection, myalgia, lethargy, sore throat, cough, and headache had a higher risk of positive results (odds ratio: 1.1–2.53). A scoring system was designed, with ≥5 points indicating acceptable sensitivity (69.5%) and specificity (63.6%). Three hundred and thirty-nine patients in the second phase were enrolled to validate the scoring system and the positive and negative predictive values were 52.0% and 73.8%.

Conclusion

The emergence of H1N1v infection is not only an important medical issue, but also a socioeconomic problem. Based on easily available clinical information, we develop a scoring system as a preliminary screening tool for the general public and first-line health care providers to evaluate the possibility of influenza virus infection. Although this study was limited by the sensitivity of rapid tests, this type of model may be a surrogate weapon when faced with overwhelming pandemic infection in the future, especially in areas with scarce medical resources.

Global burden of respiratory infections due to seasonal influenza in young children: a systematic review and meta-analysis

BACKGROUND

The global burden of disease attributable to seasonal influenza virus in children is unknown. We aimed to estimate the global incidence of and mortality from lower respiratory infections associated with influenza in children younger than 5 years.

METHODS

We estimated the incidence of influenza episodes, influenza-associated acute lower respiratory infections (ALRI), and influenza-associated severe ALRI in children younger than 5 years, stratified by age, with data from a systematic review of studies published between Jan 1, 1995, and Oct 31, 2010, and 16 unpublished population-based studies. We applied these incidence estimates to global population estimates for 2008 to calculate estimates for that year. We estimated possible bounds for influenza-associated ALRI mortality by combining incidence estimates with case fatality ratios from hospital-based reports and identifying studies with population-based data for influenza seasonality and monthly ALRI mortality.

FINDINGS

We identified 43 suitable studies, with data for around 8 million children. We estimated that, in 2008, 90 million (95% CI 49-162 million) new cases of influenza (data from nine studies), 20 million (13-32 million) cases of influenza-associated ALRI (13% of all cases of paediatric ALRI; data from six studies), and 1 million (1-2 million) cases of influenza-associated severe ALRI (7% of cases of all severe paediatric ALRI; data from 39 studies) occurred worldwide in children younger than 5 years. We estimated there were 28,000-111,500 deaths in children younger than 5 years attributable to influenza-associated ALRI in 2008, with 99% of these deaths occurring in developing countries. Incidence and mortality varied substantially from year to year in any one setting.

INTERPRETATION

Influenza is a common pathogen identified in children with ALRI and results in a substantial burden on health services worldwide. Sufficient data to precisely estimate the role of influenza in childhood mortality from ALRI are not available.

FUNDING

WHO; Bill & Melinda Gates Foundation.

Signs and symptoms predicting influenza in children: a matched case-control analysis of prospectively collected clinical data

We aimed to determine whether there are signs or symptoms that could help clinicians to distinguish between influenza and other respiratory infections. The clinical data for this matched case-control analysis were derived from a 2-year prospective cohort study of respiratory infections among children aged≤13 years. At any signs of respiratory infection, the children were examined and nasal swabs were obtained for virologic analyses. Cases were 353 children with laboratory-confirmed influenza and controls were 353 children with respiratory symptoms who tested negative for influenza. Cases and controls were matched for gender, age, and timing of the visit. In the multivariate conditional logistic regression analyses, fever was the only sign that independently predicted influenza virus infection, with odds ratios ranging from 13.55 (95% confidence interval [CI], 6.90-26.63) to 50.10 (95% CI, 16.25-154.45), depending on the degree of fever. In all analyses, the predictive capability of fever increased with incremental elevations in the child's temperature. The likelihood ratio of fever≥40.0°C in predicting influenza was 6.00 (95% CI, 2.80-12.96). Among unselected children seen as outpatients during influenza outbreaks, fever is the only reliable predictor of influenza virus infection. The optimal use of influenza-specific antiviral drugs in children may require virologic confirmation.

Influenza vaccination, diagnosis, and treatment in children

Between 2009 and 2010, the influenza H1N1 pandemic swept across the globe, disproportionately affecting the pediatric population. This pandemic strain is expected to circulate again with other seasonal influenza strains during the 2010-2011 season. This article reviews the new 2010 to 2011 Centers for Disease Control and Prevention and American Academy of Pediatrics recommendations for vaccination against the influenza virus for pediatric patients. It reviews the various testing modalities and the benefits and disadvantage of each test and offers an approach to diagnostic testing. Lastly, it reviews the indications and recommendations for treatment of children with presumed or confirmed influenza infection.

Seasonal influenza vaccination status among children with laboratory evidence of pandemic H1N1 infection

BACKGROUND

The 2009 pandemic H1N1 influenza virus emerged in March 2009 and spread rapidly, causing many thousands of deaths worldwide. A case-control study of 60 Mexican adults with H1N1 suggested that the seasonal influenza vaccine protected against H1N1 infection (odds ratio [OR], 0.27; 95% confidence interval [CI], 0.11-0.66), but subsequent studies have had varied results and few have addressed this question in children. The objective of this study was to evaluate the effect of 2008-2009 seasonal influenza vaccination on pandemic H1N1 infection in children.

METHODS

Cases (n = 165) were Kaiser Permanente Colorado inpatients and outpatients aged between 18 months and 18 years, with laboratory-confirmed pandemic H1N1 infection from May to November 2009. Controls (n = 660) were pediatric Kaiser Permanente members without documented H1N1 infection who were matched by age and gender. Seasonal influenza vaccination status was recorded for all cases and controls; conditional logistic regression analyses were used to calculate matched odds ratios.

RESULTS

Cases were more likely than controls to have underlying chronic health conditions (45% vs. 21%, P < 0.0001). Pandemic H1N1 cases were neither more nor less likely to have received the 2008-2009 seasonal influenza vaccine (OR, 1.31; 95% CI, 0.92-1.88). After adjustment for chronic medical conditions and health-seeking behavior, H1N1 cases were as likely as controls to have received the 2008-2009 seasonal influenza vaccine (OR, 1.08; 95% CI, 0.75-1.57).

CONCLUSIONS

There was no overall association--either protection or risk--between seasonal influenza vaccination and medically attended pandemic H1N1 infection in children. These results have important implications for understanding influenza immunity and future public health efforts to prevent pandemic influenza.