Clinical manifestations and consequences of influenza

Anti-influenza virus activity of the REV-ERBα agonist SR9009 and related analogues

REV-ERBα is a member of the nuclear receptor superfamily of transcription factors that aids in the regulation of many diseases. However, the prospect of using REV-ERBα for anti-influenza virus treatment remains poorly described, and there is an urgent need to develop effective anti-influenza agents due to the emergence of drug-resistant influenza viruses. In this study, eight SR9009 analogues were designed, synthesized, and evaluated for their biological activities against multiple influenza virus strains (H1N1, H3N2, adamantane- and oseltamivir-resistant H1N1 and influenza B virus), using ribavirin as the positive control. SR9009 and its analogues showed low micromolar or submicromolar EC₅₀ values and exhibited modestly improved antiviral potency compared to that of ribavirin. In particular, compound 5a possessed the most potent inhibitory activity (EC₅₀ = 0.471, 0.644, 1.644, 0.712 and 0.661 μM for A/PR/8/34, A/WSN/33, A/Wisconsin/67/2005, B/Yamagata/16/88 and Hebei/SWL1/2006, respectively). Cotransfection assays showed that all synthesized derivatives efficaciously suppressed transcription driven by the Bmal1 promoter. Mechanistic study results indicated that 5a efficiently inhibited IAV replication and interfered with the ealry stage of influenza virus life cycle. In addition, we found that 5a upregulated the key antiviral interferon-stimulated genes MxA, OAS2 and CH25H. Further in-depth transcriptome analysis revealed a series of upregulated genes that may contribute to the antiviral activities of 5a. These findings may provide an important direction for the development of new host-targeted broad-spectrum antiviral agents.

Mathematical Modeling Finds Disparate Interferon Production Rates Drive Strain-Specific Immunodynamics during Deadly Influenza Infection

The timing and magnitude of the immune response (i.e., the immunodynamics) associated with the early innate immune response to viral infection display distinct trends across influenza A virus subtypes in vivo. Evidence shows that the timing of the type-I interferon response and the overall magnitude of immune cell infiltration are both correlated with more severe outcomes. However, the mechanisms driving the distinct immunodynamics between infections of different virus strains (strain-specific immunodynamics) remain unclear. Here, computational modeling and strain-specific immunologic data are used to identify the immune interactions that differ in mice infected with low-pathogenic H1N1 or high-pathogenic H5N1 influenza viruses. Computational exploration of free parameters between strains suggests that the production rate of interferon is the major driver of strain-specific immune responses observed in vivo, and points towards the relationship between the viral load and lung epithelial interferon production as the main source of variance between infection outcomes. A greater understanding of the contributors to strain-specific immunodynamics can be utilized in future efforts aimed at treatment development to improve clinical outcomes of high-pathogenic viral strains.

School Attendance Registers for the Syndromic Surveillance of Infectious Intestinal Disease in UK Children: Protocol for a Retrospective Analysis

Background

Infectious intestinal disease (IID) is common, and children are more likely than adults both to have IID and to transmit infection onto others. Before the introduction of the vaccine, rotavirus was the leading cause of severe childhood diarrhea, with norovirus and Campylobacter predominate pathogens. Public health surveillance of IID is primarily based on health care data, and as such, illness that is managed within the community will often go undetected. School attendance registers offer a novel data set that has the potential to identify community cases and outbreaks of IID that would otherwise be missed by current health surveillance systems. Although studies have explored the role of school attendance registers in the monitoring of influenza among children, no studies have been identified that consider this approach in the surveillance of IID.

Objective

The aim of this study is to explore the role and utility of school attendance registers in the detection and surveillance of IID in children. The secondary aims are to estimate the burden of IID on school absenteeism and to assess the impact of the rotavirus vaccine on illness absence among school-aged children.

Methods

This study is a retrospective analysis of school attendance registers to investigate whether school absences due to illness can be used to capture seasonal trends and outbreaks of infectious intestinal disease among school-aged children. School absences in Merseyside, United Kingdom will be compared and combined with routine health surveillance data from primary care, laboratories, and telehealth services. These data will be used to model spatial and temporal variations in the incidence of IID and to apportion likely causes to changes in school absenteeism trends. This will be used to assess the potential utility of school attendance data in the surveillance of IID and to estimate the burden of IID absenteeism in schools. It will also inform an analysis of the impact of the rotavirus vaccine on disease within this age group.

Results

This study has received ethical approval from the University of Liverpool Research Ethics Committee (reference number 1819). Use of general practice data has been approved for the evaluation of rotavirus vaccination in Merseyside by NHS Research Ethics Committee, South Central-Berkshire REC Reference 14/SC/1140.

Conclusions

This study is unique in considering whether school attendance registers could be used to enhance the surveillance of IID. Such data have multiple potential applications and could improve the identification of outbreaks within schools, allowing early intervention to reduce transmission both within and outside of school settings. These data have the potential to act as an early warning system, identifying infections circulating within the community before they enter health care settings. School attendance data could also inform the evaluation of vaccination programs, such as rotavirus and, in time, norovirus.

International Registered Report Identifier (IRRID)

DERR1-10.2196/30078

Predictors of Influenza PCR Positivity in Acute Exacerbations of Chronic Obstructive Pulmonary Disease

Purpose

Influenza infection is an important cause of acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Clinical features predicting influenza PCR positivity are unknown. We aim to identify predictors of influenza PCR positivity in AECOPD.

Patients and Methods

A retrospective study of AECOPD cases admitted between 1st January 2016 to 30 June 2017 with combined nasal/throat swabs sent for influenza PCR (Xpert Xpress Flu/RSV) within 24 hours of admission was performed. Clinical parameters and investigations within 24 hours of admission were retrieved from electronic medical records.

Results

Influenza PCR were sent for 925 AECOPD cases (mean age 75 years, 87.9% male). There were 90 PCR positive cases (68 Influenza A, 22 Influenza B). Influenza PCR positive cases had higher temperatures, higher heart rates, lower white cell and lower eosinophil counts. Age, gender, COPD severity, comorbidities and smoking status were similar in both groups. There were no differences in blood pressure, oxygen status, neutrophil or lymphocyte counts, C reactive protein, procalcitonin or chest X-ray consolidation between groups. Higher temperature, higher heart rate, white cell count in the lowest quartile (Q1 < 8.1 x10⁹/L) and non-eosinophilic exacerbations predicted influenza PCR positivity on univariate logistic regression and these factors remained significant after multivariate adjustment (temperature adjusted odds ratio [adj OR] 1.324 [1.009–1.737], p = 0.043; heart rate adj OR 1.017 [1.004–1.030], p = 0.011; white cell count Q1 adj OR 3.330 [1.690–6.562], p = 0.001; eosinophilic exacerbations adj OR 0.390 [0.202–0.756], p = 0.005).

Conclusion

Higher temperature, higher heart rate, low white cell count (especially when < 8.1 x10⁹/L) and non-eosinophilic exacerbations are independent predictors of influenza PCR positivity in AECOPD cases.

School-based surveillance of acute infectious disease in children: a systematic review

BACKGROUND

Syndromic surveillance systems are an essential component of public health surveillance and can provide timely detection of infectious disease cases and outbreaks. Whilst surveillance systems are generally embedded within healthcare, there is increasing interest in novel data sources for monitoring trends in illness, such as over-the-counter purchases, internet-based health searches and worker absenteeism. This systematic review considers the utility of school attendance registers in the surveillance of infectious disease outbreaks and occurrences amongst children.

METHODS

We searched eight databases using key words related to school absence, infectious disease and syndromic surveillance. Studies were limited to those published after 1st January 1995. Studies based in nursery schools or higher education settings were excluded. Article screening was undertaken by two independent reviewers using agreed eligibility criteria. Data extraction was performed using a standardised data extraction form. Outcomes included estimates of absenteeism, correlation with existing surveillance systems and associated lead or lag times.

RESULTS

Fifteen studies met the inclusion criteria, all of which were concerned with the surveillance of influenza. The specificity of absence data varied between all-cause absence, illness absence and syndrome-specific absence. Systems differed in terms of the frequency of data submissions from schools and the level of aggregation of the data. Baseline rates of illness absence varied between 2.3-3.7%, with peak absences ranging between 4.1-9.8%. Syndrome-specific absenteeism had the strongest correlation with other surveillance systems (r = 0.92), with illness absenteeism generating mixed results and all-cause absenteeism performing the least well. A similar pattern of results emerged in terms of lead and lag times, with influenza-like illness (ILI)-specific absence providing a 1-2 week lead time, compared to lag times reported for all-cause absence data and inconsistent results for illness absence data.

CONCLUSION

Syndrome-specific school absences have potential utility in the syndromic surveillance of influenza, demonstrating good correlation with healthcare surveillance data and a lead time of 1-2 weeks ahead of existing surveillance measures. Further research should consider the utility of school attendance registers for conditions other than influenza, to broaden our understanding of the potential application of this data for infectious disease surveillance in children.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO 2019 CRD42019119737.

The effect of control strategies to reduce social mixing on outcomes of the COVID-19 epidemic in Wuhan, China: a modelling study

BACKGROUND

In December, 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel coronavirus, emerged in Wuhan, China. Since then, the city of Wuhan has taken unprecedented measures in response to the outbreak, including extended school and workplace closures. We aimed to estimate the effects of physical distancing measures on the progression of the COVID-19 epidemic, hoping to provide some insights for the rest of the world.

METHODS

To examine how changes in population mixing have affected outbreak progression in Wuhan, we used synthetic location-specific contact patterns in Wuhan and adapted these in the presence of school closures, extended workplace closures, and a reduction in mixing in the general community. Using these matrices and the latest estimates of the epidemiological parameters of the Wuhan outbreak, we simulated the ongoing trajectory of an outbreak in Wuhan using an age-structured susceptible-exposed-infected-removed (SEIR) model for several physical distancing measures. We fitted the latest estimates of epidemic parameters from a transmission model to data on local and internationally exported cases from Wuhan in an age-structured epidemic framework and investigated the age distribution of cases. We also simulated lifting of the control measures by allowing people to return to work in a phased-in way and looked at the effects of returning to work at different stages of the underlying outbreak (at the beginning of March or April).

FINDINGS

Our projections show that physical distancing measures were most effective if the staggered return to work was at the beginning of April; this reduced the median number of infections by more than 92% (IQR 66-97) and 24% (13-90) in mid-2020 and end-2020, respectively. There are benefits to sustaining these measures until April in terms of delaying and reducing the height of the peak, median epidemic size at end-2020, and affording health-care systems more time to expand and respond. However, the modelled effects of physical distancing measures vary by the duration of infectiousness and the role school children have in the epidemic.

INTERPRETATION

Restrictions on activities in Wuhan, if maintained until April, would probably help to delay the epidemic peak. Our projections suggest that premature and sudden lifting of interventions could lead to an earlier secondary peak, which could be flattened by relaxing the interventions gradually. However, there are limitations to our analysis, including large uncertainties around estimates of R0 and the duration of infectiousness.

FUNDING

Bill & Melinda Gates Foundation, National Institute for Health Research, Wellcome Trust, and Health Data Research UK.

Is there a clinical difference between influenza A and B virus infections in hospitalized patients? : Results after routine polymerase chain reaction point-of-care testing in the emergency room from 2017/2018

PURPOSE

The clinical presentation, complications and mortality in molecularly confirmed influenza A and B infections were analyzed.

METHODS

This retrospective observational single-centre study included all influenza positive patients older than 18 years who were hospitalized and treated at the flu isolation ward during 2017/2018. The diagnosis was based on point-of-care tests with the Alere^TM.

RESULTS

Of the 396 patients tested positive for influenza, 24.2% had influenza A and 75.8% influenza B. Influenza A patients were younger (median age 67.5 years vs. 77 years, p < 0.001), were more often smokers (27.7% vs. 16.8%, p = 0.021), had chronic pulmonary diseases more frequently (39.6% vs. 26.3%, p = 0.013), presented with a higher body temperature (38.6 °C vs. 38.3 °C, p = 0.004), leucocyte count (8 G/L vs. 6.8 G/L, p = 0.002), C‑reactive protein (CRP) level (41 mg/l vs. 23 mg/l, p < 0.001) and had dyspnea more often (41.7% vs. 28%, p = 0.012). Influenza B patients had an underlying chronic kidney disease in 37% vs. 18.8% (p < 0.001) and presented with vomiting on admission more frequently (21.7% vs. 11.5%, p = 0.027). Influenza A patients were admitted for 8 days vs. 7 days (p = 0.023). There were no differences in the rate of complications; however, 22 (5.6%) patients died during the hospital stay. The in-hospital mortality was higher in influenza A patients (8.3% vs 4.7%, p = 0.172).

CONCLUSION

Some differences were found between influenza A and B virus infections but symptoms were overlapping, which necessitates polymerase chain reaction point-of-care testing for accurate diagnosis. Influenza A was a more severe disease than influenza B during the period 2017/2018.

Influenza virus infection: an approach to identify predictors for in-hospital and 90-day mortality from patients in Vienna during the season 2017/18

BACKGROUND

Seasonal influenza outbreaks are associated with increased mortality and hospitalisation rates. Herein we tried to identify predictors of mortality in hospitalised patients with influenza virus infection.

MATERIALS/METHODS

In this exploratory retrospective observational single-centre-study we included all influenza-positive patients older than 18 years who were hospitalised and treated at the flu-isolation-ward during the influenza season 2017/18. Diagnosis was based on point-of-care-test with the Alere™ i. First we performed χ² tests and Mann-Whitney U tests to identify predictors of mortality. Significant variables were used in a stepwise-forward-logistic-regression-model to predict in-hospital and 90-day mortality.

RESULTS

Of the 396 patients who tested positive for influenza 96 (24.2%) had influenza A and 300 (75.8%) influenza B. Twenty-two (5.6%) died in hospital and the 90-day mortality rate was 9.4%. In the stepwise logistic regression older age (OR 1.1 per year 95% CI 1.03-1.17), history of atrial fibrillation (OR 5.91 95% CI 1.91-18.34), dementia (OR 3.98 95% CI 1.24-12.78), leucocyte count (OR 1.11 per G/L 95% CI 1.03-1.20), pneumonia (OR 4.39 95% CI 1.44-13.39) and acute heart failure (OR 23.15 95% CI 4.33-123.76) increased the risk of in-hospital mortality. The risk for 90-day mortality was increased by older age (OR 1.04 per year 95% CI 1.01-1.07), history of atrial fibrillation (OR 3.1, 95% CI 1.36-7.05), history of congestive heart failure (OR 4.7 95% CI 1.94-11.48), pneumonia (OR 3.2 95% CI 1.45-6.91) and decreased by statin use (OR 0.28 95% CI 0.10-0.78).

CONCLUSIONS

Older age, history of atrial fibrillation and pneumonia are associated with increased risk of influenza-associated in-hospital and 90-day mortality. Statin use may decrease 90-day mortality.

Unsupervised extraction of epidemic syndromes from participatory influenza surveillance self-reported symptoms

Seasonal influenza surveillance is usually carried out by sentinel general practitioners (GPs) who compile weekly reports based on the number of influenza-like illness (ILI) clinical cases observed among visited patients. This traditional practice for surveillance generally presents several issues, such as a delay of one week or more in releasing reports, population biases in the health-seeking behaviour, and the lack of a common definition of ILI case. On the other hand, the availability of novel data streams has recently led to the emergence of non-traditional approaches for disease surveillance that can alleviate these issues. In Europe, a participatory web-based surveillance system called Influenzanet represents a powerful tool for monitoring seasonal influenza epidemics thanks to aid of self-selected volunteers from the general population who monitor and report their health status through Internet-based surveys, thus allowing a real-time estimate of the level of influenza circulating in the population. In this work, we propose an unsupervised probabilistic framework that combines time series analysis of self-reported symptoms collected by the Influenzanet platforms and performs an algorithmic detection of groups of symptoms, called syndromes. The aim of this study is to show that participatory web-based surveillance systems are capable of detecting the temporal trends of influenza-like illness even without relying on a specific case definition. The methodology was applied to data collected by Influenzanet platforms over the course of six influenza seasons, from 2011-2012 to 2016-2017, with an average of 34,000 participants per season. Results show that our framework is capable of selecting temporal trends of syndromes that closely follow the ILI incidence rates reported by the traditional surveillance systems in the various countries (Pearson correlations ranging from 0.69 for Italy to 0.88 for the Netherlands, with the sole exception of Ireland with a correlation of 0.38). The proposed framework was able to forecast quite accurately the ILI trend of the forthcoming influenza season (2016-2017) based only on the available information of the previous years (2011-2016). Furthermore, to broaden the scope of our approach, we applied it both in a forecasting fashion to predict the ILI trend of the 2016-2017 influenza season (Pearson correlations ranging from 0.60 for Ireland and UK, and 0.85 for the Netherlands) and also to detect gastrointestinal syndrome in France (Pearson correlation of 0.66). The final result is a near-real-time flexible surveillance framework not constrained by any specific case definition and capable of capturing the heterogeneity in symptoms circulation during influenza epidemics in the various European countries.

Production and characterization of a conserved M2e peptide-based specific IgY antibody: evaluation of the diagnostic potential via conjugation with latex nanoparticles

Antibodies play an important role in combating and controlling viral diseases such as influenza. Immunoglobulin Y (IgY) antibodies have several advantages such as a less invasive manufacturing process, ease of isolation, higher affinity compared with IgG antibodies, and cost-effectiveness. To date, although specific IgY production has been performed for different strains of influenza A, to the best of our knowledge, an IgY against the M2e peptide has not been produced. In the current study, IgY antibodies are produced, purified, and characterized using the M2e peptide sequence for the first time with the intent to apply them for the diagnosis of influenza A virus. Anti-M2e IgY antibodies are obtained from eggs using a two-step purification method. The activity and characterization of the antibodies are determined using an enzyme-linked immunosorbent assay, a nano-spectrophotometer, an SDS-Page assay, and a Western Blot analysis. Finally, anti-M2e IgY antibodies are conjugated to the latex nanoparticles, and the reaction between the influenza A virus and the nanoparticles is demonstrated using light microscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy. In conclusion, this study shows that anti-M2e IgY antibodies can contribute to the diagnosis, treatment, and prevention of the influenza A virus.

Increasing influenza vaccination rates via low cost messaging interventions

This article tests low cost interventions to increase influenza vaccination rates. By changing an email announcement sent out to employees in 2014 (n > 30,000), the following interventions are tested: incentives, attention to the negative impacts of not get vaccinated, and showing a map to the vaccination centers at the end of the email announcement. Only the map condition helped increase influenza vaccination rates. The use of low-cost interventions can improve influenza vaccination rates though not all interventions work as well as others in the field. In particular, while including maps helped increase vaccination rates, other factors such as negative impact reminders and incentives, which previous studies have found to be successful in the laboratory, did not.

Influenza in Older Adults

Annually, influenza viruses cause significant disease in older adults, varying with the virulence of the circulating strain, prior exposure to circulating strain, and influenza vaccine effectiveness. Older adults often present atypically (eg, without fever) and with complications of influenza infection such as chronic obstructive pulmonary disease and congestive heart failure exacerbations. Prevention methods include antiviral medications and vaccines. Current influenza vaccines have moderate effectiveness for the prevention of hospitalization, but newer more immunogenic vaccines designed for adults 65 years of age and older have been licensed.

Projecting social contact matrices in 152 countries using contact surveys and demographic data

Heterogeneities in contact networks have a major effect in determining whether a pathogen can become epidemic or persist at endemic levels. Epidemic models that determine which interventions can successfully prevent an outbreak need to account for social structure and mixing patterns. Contact patterns vary across age and locations (e.g. home, work, and school), and including them as predictors in transmission dynamic models of pathogens that spread socially will improve the models' realism. Data from population-based contact diaries in eight European countries from the POLYMOD study were projected to 144 other countries using a Bayesian hierarchical model that estimated the proclivity of age-and-location-specific contact patterns for the countries, using Markov chain Monte Carlo simulation. Household level data from the Demographic and Health Surveys for nine lower-income countries and socio-demographic factors from several on-line databases for 152 countries were used to quantify similarity of countries to estimate contact patterns in the home, work, school and other locations for countries for which no contact data are available, accounting for demographic structure, household structure where known, and a variety of metrics including workforce participation and school enrolment. Contacts are highly assortative with age across all countries considered, but pronounced regional differences in the age-specific contacts at home were noticeable, with more inter-generational contacts in Asian countries than in other settings. Moreover, there were variations in contact patterns by location, with work-place contacts being least assortative. These variations led to differences in the effect of social distancing measures in an age structured epidemic model. Contacts have an important role in transmission dynamic models that use contact rates to characterize the spread of contact-transmissible diseases. This study provides estimates of mixing patterns for societies for which contact data such as POLYMOD are not yet available.

The presence of fever in adults with influenza and other viral respiratory infections

We compared the rates of fever in adult subjects with laboratory-confirmed influenza and other respiratory viruses and examined the factors that predict fever in adults. Symptom data on 158 healthcare workers (HCWs) with a laboratory-confirmed respiratory virus infection were collected using standardized data collection forms from three separate studies. Overall, the rate of fever in confirmed viral respiratory infections in adult HCWs was 23·4% (37/158). Rates varied by virus: human rhinovirus (25·3%, 19/75), influenza A virus (30%, 3/10), coronavirus (28·6%, 2/7), human metapneumovirus (28·6%, 2/7), respiratory syncytial virus (14·3%, 4/28) and parainfluenza virus (8·3%, 1/12). Smoking [relative risk (RR) 4·65, 95% confidence interval (CI) 1·33-16·25] and co-infection with two or more viruses (RR 4·19, 95% CI 1·21-14·52) were significant predictors of fever. Fever is less common in adults with confirmed viral respiratory infections, including influenza, than described in children. More than 75% of adults with a viral respiratory infection do not have fever, which is an important finding for clinical triage of adult patients with respiratory infections. The accepted definition of 'influenza-like illness' includes fever and may be insensitive for surveillance when high case-finding is required. A more sensitive case definition could be used to identify adult cases, particularly in event of an emerging viral infection.

Effect of an Echinacea-Based Hot Drink Versus Oseltamivir in Influenza Treatment: A Randomized, Double-Blind, Double-Dummy, Multicenter, Noninferiority Clinical Trial

BACKGROUND

Echinacea has antiviral activity against influenza viruses in vitro and has traditionally been used for treatment of colds and flu.

OBJECTIVES

This randomized, double-blind, double-dummy, multicenter, controlled clinical trial compared a new echinacea formulation with the neuraminidase inhibitor oseltamivir, the gold standard treatment for influenza.

METHODS

Following informed consent, 473 patients with early influenza symptoms (≤48 hours) were recruited in primary care in the Czech Republic and randomized to either 5 days of oseltamivir followed by 5 days of placebo, or 10 days of an Echinacea purpurea-based formulation called Echinaforce Hotdrink (A. Vogel Bioforce AG, Roggwil, Switzerland). The proportion of recovered patients (influenza symptoms rated as absent or mild in the evening) was analyzed for noninferiority between treatment groups using a generalized Wilcoxon test with significance level α = 0.05 (2-sided) and using a CI approach in the per-protocol sample.

RESULTS

Recovery from illness was comparable in the 2 treatment groups at 1.5% versus 4.1% after 1 day, 50.2% versus 48.8% after 5 days, and 90.1% versus 84.8% after 10 days of treatment with Echinaforce Hotdrink and oseltamivir, respectively. Noninferiority was demonstrated for each day and overall (95% CI, 0.487-0.5265 by generalized Wilcoxon test). Very similar results were obtained in the group with virologically confirmed influenza virus infections and in a retrospective analysis during the peak influenza period. The incidence of complications was lower with Echinaforce Hotdrink than with oseltamivir (2.46% vs 6.45%; P = 0.076) and fewer adverse events (particularly nausea and vomiting) were observed with Echinaforce Hotdrink.

CONCLUSIONS

Echinaforce Hotdrink is as effective as oseltamivir in the early treatment of clinically diagnosed and virologically confirmed influenza virus infections with a reduced risk of complications and adverse events. It appears to be an attractive treatment option, particularly suitable for self-care. Clinical trial identifier: Eudra-CT: 2010-021571-88. (Curr Ther Res Clin Exp. 2015; 77:66-72).

Clinical predictors for laboratory-confirmed influenza infections: exploring case definitions for influenza-like illness

OBJECTIVE

To identify clinical signs and symptoms (ie, "terms") that accurately predict laboratory-confirmed influenza cases and thereafter generate and evaluate various influenza-like illness (ILI) case definitions for detecting influenza. A secondary objective explored whether surveillance of data beyond the chief complaint improves the accuracy of predicting influenza.

DESIGN

Retrospective, cross-sectional study.

SETTING

Large urban academic medical center hospital.

PARTICIPANTS

A total of 1,581 emergency department (ED) patients who received a nasopharyngeal swab followed by rRT-PCR testing between August 30, 2009, and January 2, 2010, and between November 28, 2010, and March 26, 2011.

METHODS

An electronic surveillance system (GUARDIAN) scanned the entire electronic medical record (EMR) and identified cases containing 29 clinical terms relevant to influenza. Analyses were conducted using logistic regressions, diagnostic odds ratio (DOR), sensitivity, and specificity.

RESULTS

The best predictive model for identifying influenza for all ages consisted of cough (DOR=5.87), fever (DOR=4.49), rhinorrhea (DOR=1.98), and myalgias (DOR=1.44). The 3 best case definitions that included combinations of some or all of these 4 symptoms had comparable performance (ie, sensitivity=89%-92% and specificity=38%-44%). For children <5 years of age, the addition of rhinorrhea to the fever and cough case definition achieved a better balance between sensitivity (85%) and specificity (47%). For the fever and cough ILI case definition, using the entire EMR, GUARDIAN identified 37.1% more influenza cases than it did using only the chief complaint data.

CONCLUSIONS

A simplified case definition of fever and cough may be suitable for implementation for all ages, while inclusion of rhinorrhea may further improve influenza detection for the 0-4-year-old age group. Finally, ILI surveillance based on the entire EMR is recommended.

Use of simple clinical and laboratory predictors to differentiate influenza from dengue and other febrile illnesses in the emergency room

Background

Clinical differentiation of influenza from dengue and other febrile illnesses (OFI) is difficult, and available rapid diagnostic tests have limited sensitivity.

Methods

We conducted a retrospective study to compare clinical and laboratory findings between (i) influenza and dengue and (ii) influenza and OFI.

Results

Of 849 enrolled patients, the mean time between illness onset and hospital presentation was 1.7, 3.7, and 3 days for influenza, dengue, and OFI, respectively. Among pediatric patients (≤18 years) (445 influenza, 24 dengue, and 130 OFI), we identified absence of rashes, no leukopenia, and no marked thrombocytopenia (platelet counts <100 × 10⁹ cells/L) as predictors to distinguish influenza from dengue, whereas rhinorrhea, malaise, sore throat, and mild thrombocytopenia (platelet counts 100-149 × 10⁹/L) were predictors that differentiated influenza from OFI. Among adults (>18 years) (81 influenza, 124 dengue, and 45 OFI), no leukopenia and no marked thrombocytopenia distinguished influenza from dengue, while rhinorrhea and malaise differentiated influenza from OFI. A diagnostic algorithm developed to distinguish influenza from dengue using rash, leukopenia, and marked thrombocytopenia showed >90% sensitivity to identify influenza in pediatric patients.

Conclusions

This study identified simple clinical and laboratory parameters that can assist clinicians to distinguish influenza from dengue and OFI. These findings may help clinicians diagnose influenza and facilitate appropriate management of affected patients, particularly in resource-poor settings.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-014-0623-z) contains supplementary material, which is available to authorized users.

The Epidemiology of Upper Respiratory Infections at a Tertiary Care Center: Prevalence, Seasonality, and Clinical Symptoms

Improved multiplex PCR detection methods are facilitating the correlation of the etiology of respiratory tract infections with specific symptoms or clinical manifestations. We conducted a retrospective analysis of the incidence of respiratory pathogens and initial symptoms in 1,286 patients at a tertiary care center tested by multiplex respiratory pathogen PCR from July 1, 2012, to June 30, 2013. Rhinovirus/enterovirus (Rhino/Entero) infections were the most prevalent (25.4%) followed by respiratory syncytial virus (RSV) (13.6%) and influenza A (6.2%). Eleven percent of patients were positive for multiple analytes with Rhino/Entero and RSV being the most common combination. Asthma or asthma exacerbation was the most common presenting symptom in patients positive for Rhino/Entero (38.4%) or positive for Rhino/Entero along with RSV or hMPV (34.8%). Of the patients positive for Rhino/Entero and presenting with asthma, 97% were ≤17 years of age. RSV positive patients most commonly presented with respiratory distress (40.3%) followed by asthma (18%) or pneumonia (18%). The most prevalent initial clinical manifestation for influenza was fever (27.4%) followed by respiratory distress (13%) or pneumonia (11.9%). The significant percentage of patients positive for Rhino/Entero virus presenting with asthma supports the role of rhinovirus as an important trigger for asthma exacerbation.

Characterization of glycan binding specificities of influenza B viruses with correlation with hemagglutinin genotypes and clinical features

The carbohydrate binding specificities are different among avian and human influenza A viruses and may affect the tissue tropism and transmission of these viruses. The glycan binding biology for influenza B, however, has not been systematically characterized. Glycan binding specificities of influenza B viral isolates were analyzed and correlated to hemagglutinin (HA) genotypes and clinical manifestations. A newly developed solution glycan array was applied to characterize the receptor binding specificities of influenza B virus clinical isolates from 2001 to 2007 in Taiwan. Thirty oligosaccharides which include α-2,3 and α-2,6 linkage glycans were subjected to analysis. The glycan binding patterns of 53 influenza B isolates could be categorized into three groups and were well correlated to their HA genotypes. The Yamagata-like strains predominantly bound to α-2,6-linkage glycan (24:29, 83%) while Victoria-like strains preferentially bound to both α-2,3- and α-2,6-linkage glycans (13:24, 54%). A third group of viruses bound to sulfated glycans and these all belonged to Victoria-like strains. Based on the HA sequences, Asn-163, Glu-198, Ala-202, and Lys-203 were conserved among Victoria-like strains which may influence their carbohydrate recognition. The viruses bound to dual type glycans were more likely to be associated with the development of bronchopneumonia and gastrointestinal illness than those bound only to α-2,6 sialyl glycans (P < 0.05). Glycan binding analyses provide additional information to monitor the antigenic shift, tissue tropism, and transmission capability of influenza B viruses, and will contribute to virus surveillance and vaccine strain selection.

Influenza vaccination for older adults

Influenza vaccines were developed in the 1930s and were shown in randomized clinical trials to prevent influenza in young healthy adults. The significant morbidity and mortality associated with influenza in adults, age 65 y and older, prompted the early recommendation for influenza vaccination in that age group, based on efficacy data in younger adults. Subsequently a number of studies have demonstrated vaccine effectiveness in older adults, but it appears to be lower than in younger adults. New vaccines are being developed with enhanced immunogenicity to improve the protection of older adults. In the meantime, the currently licensed influenza vaccines need to be administered annually to prevent the estimated 90,000 hospitalizations and 5,000 deaths attributed to influenza in adults ≥65 y of age each year.

Adaption of seasonal H1N1 influenza virus in mice

The experimental infection of a mouse lung with influenza A virus has proven to be an invaluable model for studying the mechanisms of viral adaptation and virulence. The mouse adaption of human influenza A virus can result in mutations in the HA and other proteins, which is associated with increased virulence in mouse lungs. In this study, a mouse-adapted seasonal H1N1 virus was obtained through serial lung-to-lung passages and had significantly increased virulence and pathogenicity in mice. Genetic analysis indicated that the increased virulence of the mouse-adapted virus was attributed to incremental acquisition of three mutations in the HA protein (T89I, N125T, and D221G). However, the mouse adaption of influenza A virus did not change the specificity and affinity of receptor binding and the pH-dependent membrane fusion of HA, as well as the in vitro replication in MDCK cells. Notably, infection with the mouse adapted virus induced severe lymphopenia and modulated cytokine and chemokine responses in mice. Apparently, mouse adaption of human influenza A virus may change the ability to replicate in mouse lungs, which induces strong immune responses and inflammation in mice. Therefore, our findings may provide new insights into understanding the mechanisms underlying the mouse adaption and pathogenicity of highly virulent influenza viruses.

Impact of pneumococcal conjugate vaccination of infants on pneumonia and influenza hospitalization and mortality in all age groups in the United States

A seven-valent pneumococcal conjugate vaccine (PCV7) introduced in the United States in 2000 has been shown to reduce invasive pneumococcal disease (IPD) in both vaccinated children and adults through induction of herd immunity. We assessed the impact of infant immunization on pneumococcal pneumonia hospitalizations and mortality in all age groups using Health Care Utilization Project State Inpatient Databases (SID) for 1996 to 2006 from 10 states; SID contain 100% samples of ICD9-coded hospitalization data for the selected states. Compared to a 1996–1997 through 1998–1999 baseline, by the 2005–2006 season, both IPD and pneumococcal pneumonia hospitalizations and deaths had decreased substantially in all age groups, including a 47% (95% confidence interval [CI], 38 to 54%) reduction in nonbacteremic pneumococcal pneumonia (ICD9 code 481 with no codes indicating IPD) in infants <2 years old and a 54% reduction (CI, 53 to 56%) in adults ≥65 years of age. A model developed to calculate the total burden of pneumococcal pneumonia prevented by infant PCV7 vaccination in the United States from 2000 to 2006 estimated a reduction of 788,838 (CI, 695,406 to 875,476) hospitalizations for pneumococcal pneumonia. Ninety percent of the reduction in model-attributed pneumococcal pneumonia hospitalizations occurred through herd immunity among adults 18 years old and older; similar proportions were found in pneumococcal disease mortality prevented by the vaccine. In the first seasons after PCV introduction, when there were substantial state differences in coverage among <5-year-olds, states with greater coverage had significantly fewer influenza-associated pneumonia hospitalizations among children, suggesting that PCV7 use also reduces influenza-attributable pneumonia hospitalizations.

Pneumonia is the world’s leading cause of death in children and the leading infectious cause of death among U.S. adults 65 years old and older. Pneumococcal conjugate vaccination of infants has previously been shown to reduce invasive pneumococcal disease (IPD) among seniors through prevention of pneumococcal transmission from infants to adults (herd immunity). Our analysis documents a significant vaccine-associated reduction not only in IPD but also in pneumococcal pneumonia hospitalizations and inpatient mortality rates among both vaccinated children and unvaccinated adults. We estimate that fully 90% of the reduction in the pneumonia hospitalization burden occurred among adults. Moreover, states that more rapidly introduced their infant pneumococcal immunization programs had greater reductions in influenza-associated pneumonia hospitalization of children, presumably because the vaccine acts to prevent the pneumococcal pneumonia that frequently follows influenza virus infection. Our results indicate that seven-valent pneumococcal conjugate vaccine use has yielded far greater benefits through herd immunity than have previously been recognized.

Safety review: squalene and thimerosal in vaccines

Few studies show the reluctance of the people to get vaccinated against A (H1N1) influenza for fear of side effects of squalene (MF59, AS03, AF03) and thimerosal. The aim of this paper is to assess the safety in using these adjuvants and preservative reviewing data of clinical trials relative to which formulation includes these compounds. In the current state of knowledge, these vaccines have proved to be effective even though they more frequently give local adverse events than non-adjuvanted influenza vaccines. Systemic side effects are generally not serious. In the studies, adjuvanted vaccines do not increase neither the risk of Guillain Barre syndrome nor auto-immune diseases. There is no convincing evidence that exposure to thimerosal in vaccines had any deletorious effect on physiological outcome.

Evaluation of an influenza-like illness case definition in the diagnosis of influenza among patients with acute febrile illness in Cambodia

Background

Influenza-like illness (ILI) is often defined as fever (>38.0°C) with cough or sore throat. In this study, we tested the sensitivity, specificity, and positive and negative predictive values of this case definition in a Cambodia patient population.

Methods

Passive clinic-based surveillance was established at nine healthcare centers to identify the causes of acute undifferentiated fever in patients aged two years and older seeking treatment. Fever was defined as tympanic membrane temperature >38°C lasting more than 24 hours and less than 10 days. Influenza virus infections were identified by polymerase chain reaction.

Results

From July 2008 to December 2008, 2,639 patients were enrolled. From 884 (33%) patients positive for influenza, 652 presented with ILI and 232 acute fever patients presented without ILI. Analysis by age group identified no significant differences between influenza positive patients from the two groups. Positive predictive values (PPVs) varied during the course of the influenza season and among age groups.

Conclusion

The ILI case definition can be used to identify a significant percentage of patients with influenza infection during the influenza season in Cambodia, assisting healthcare providers in its diagnosis and treatment. However, testing samples based on the criteria of fever alone increased our case detection by 34%.

The diagnosis of viral respiratory disease in older adults

Viral respiratory disease in older adults has been increasingly recognized as a significant cause of hospitalizations and death. Unfortunately, the recognition and diagnosis of infection due to many viral respiratory pathogens in older adults can be elusive because of atypical clinical presentations and the insensitivity of current laboratory diagnostic tests in this population. For influenza diagnosis, rapid antigen tests followed by viral culture (if antigen test results are negative), can be useful in older adults as long as clinicians are mindful of test limitations. Although specific, rapid antigen tests are insensitive in this population. Erroneous negative results may lead to delays in timely administration of antiviral treatment and institution of appropriate isolation precautions. The increasing availability of new, rapid, and sensitive molecular diagnostics, such as polymerase chain reaction testing, should provide more accurate and timely diagnoses of viral respiratory infections in older adults in the near future.

Immunogenicity of three different influenza vaccines against homologous and heterologous strains in nursing home elderly residents

We studied whether MF59-adjuvanted influenza vaccine improves immunity against drifted influenza strains in institutionalised elderly with underling chronic health conditions. Sera from a randomized study, comparing MF59-adjuvanted (Sub/MF59, n = 72), virosomal (SVV, n = 39), and split (n = 88) vaccines, were retested using a hemagglutination inhibition (HI) assay against homologous (Northern Hemisphere [NH] 1998/99) and drifted (NH 2006/07) strains. Corrected postvaccination HI antibody titres were significantly higher with Sub/MF59 than SVV for all strains; GMTs against homologous A/H3N2 and B and both drifted A strains were significantly higher for Sub/MF59 than split. Seroprotection rates and mean-fold titer increases were generally higher with Sub/MF59 for all A influenza strains. MF59-adjuvanted influenza vaccine induced greater and broader immune responses in elderly people with chronic conditions, than conventional virosomal and split vaccines, particularly for A/H1 and A/H3 strains, potentially giving clinical benefit in seasons where antigenic mismatch occurs.

Pandemic influenza: implications for occupational medicine

This article reviews the biological and occupational medicine literature related to H5N1 pandemic influenza and its impact on infection control, cost and business continuity in settings outside the health care community. The literature on H5N1 biology is reviewed including the treatment and infection control mechanisms as they pertain to occupational medicine. Planning activity for the potential arrival of pandemic avian influenza is growing rapidly. Much has been published on the molecular biology of H5N1 but there remains a paucity of literature on the occupational medicine impacts to organizations. This review summarizes some of the basic science surrounding H5N1 influenza and raises some key concerns in pandemic planning for the occupational medicine professional. Workplaces other than health care settings will be impacted greatly by an H5N1 pandemic and the occupational physician will play an essential role in corporate preparation, response, and business continuity strategies.

Severe seasonal influenza in ferrets correlates with reduced interferon and increased IL-6 induction

Even though ferrets are one of the principal animal models for influenza pathogenesis, the lack of suitable immunological reagents has so far limited their use in host response studies. Using recently established real-time PCR assays for a panel of ferret cytokines, we analyzed the local ferret immune response to human influenza isolates of the H1N1 and H3N2 subtypes that varied in their virulence. We observed that the severity of clinical signs correlated with gross- and histopathological changes in the lungs and was subtype-independent. Strains causing a mild disease were associated with a strong and rapid innate response and upregulation of IL-8, while severe infections were characterized by a lesser induction of type I and II interferons and strong IL-6 upregulation. These findings suggest that more virulent strains may interfere more efficiently with the host response at early disease stages.

Clinical features of children infected with different strains of influenza B in southern Taiwan

BACKGROUND

This study was designed to determine the clinical characteristics of children infected with different strains of influenza B viruses isolated in southern Taiwan. The clinical features were compared with influenza A infection occurring in the same period.

METHODS

All children enrolled in the study had laboratory-confirmed infection with influenza A or B viruses. Influenza B speciation was performed by RNA extraction, cDNA synthesis, and amplification by polymerase chain reaction and sequencing. Demographic data, clinical findings, diagnoses, and outcomes were obtained.

RESULTS

During the study period, 163 strains of influenza A and 118 strains of influenza B were isolated. The Yamagata-like strains were most prevalent in 2001. New reassortant strains were identified since 2002 and became predominant in 2005 and 2006. Children with influenza B were more likely than those with influenza A to be diagnosed as upper respiratory tract infection, myositis, and gastroenteritis (P < 0.05). Children infected with Yamagata-like strains were more likely to develop lower respiratory tract infection (P < 0.05) and accounted for all cases of invasive disease. Children infected with the Victoria-like group had the longest hospital stays associated with severe bacterial superinfection.

CONCLUSIONS

Currently new reassortant influenza B viruses are the predominant strains circulating in southern Taiwan. There is considerable similarity of clinical features between influenza A and B in children. The Yamagata-like strains were associated with more invasive infections. Continuous influenza virus surveillance is essential particularly in Taiwan where pandemic strains tend to appear earlier than in other countries.

Community-acquired viral pneumonia

Advanced age often is associated with functional and immunologic decline and chronic cardiopulmonary diseases that predispose to pneumonia when viral infection occurs. Influenza virus remains the primary viral pathogen in the elderly, although the impact of the other respiratory viruses remains to be defined. The clinical syndromes associated with respiratory viruses frequently are indistinguishable from one another or bacterial pathogens; often, viral illness in older adults exacerbates underlying conditions, complicating diagnosis. Antiviral therapy is available for influenza A and B; specific viral diagnosis, particularly with the use of rapid antigen detection, may be useful for clinical management. Treatment for other viruses primarily is supportive.

Integrated molecular signature of disease: analysis of influenza virus-infected macaques through functional genomics and proteomics

Recent outbreaks of avian influenza in humans have stressed the need for an improved nonhuman primate model of influenza pathogenesis. In order to further develop a macaque model, we expanded our previous in vivo genomics experiments with influenza virus-infected macaques by focusing on the innate immune response at day 2 postinoculation and on gene expression in affected lung tissue with viral genetic material present. Finally, we sought to identify signature genes for early infection in whole blood. For these purposes, we infected six pigtailed macaques (Macaca nemestrina) with reconstructed influenza A/Texas/36/91 virus and three control animals with a sham inoculate. We sacrificed one control and two experimental animals at days 2, 4, and 7 postinfection. Lung tissue was harvested for pathology, gene expression profiling, and proteomics. Blood was collected for genomics every other day from each animal until the experimental endpoint. Gross and microscopic pathology, immunohistochemistry, viral gene expression by arrays, and/or quantitative real-time reverse transcription-PCR confirmed successful yet mild infections in all experimental animals. Genomic experiments were performed using macaque-specific oligonucleotide arrays, and high-throughput proteomics revealed the host response to infection at the mRNA and protein levels. Our data showed dramatic differences in gene expression within regions in influenza virus-induced lesions based on the presence or absence of viral mRNA. We also identified genes tightly coregulated in peripheral white blood cells and in lung tissue at day 2 postinoculation. This latter finding opens the possibility of using gene expression arrays on whole blood to detect infection after exposure but prior to onset of symptoms or shedding.

The unmet need in the elderly: Designing new influenza vaccines for older adults

Influenza is a serious illness and probably the single most important cause of excess disability and mortality during the winter months. In spite of limited efficacy in older adults, influenza vaccination is nevertheless a cost-saving medical intervention since it does reduce hospitalisation and death rates due to pneumonia, exacerbations of heart failure and, surprisingly, heart attacks and strokes. Yet hospitalisation and death rates for acute respiratory illnesses continue to rise in spite of widespread vaccination programs. As a person ages, the immune response to antigenic stimulation with the influenza virus shifts toward T helper type 2 cytokine production. This is associated with a relative reduction in cytotoxic T-cell activity and a reduced capacity to destroy infected host cells and clear the virus from infected lung tissue. Breakthrough strategies to improve the current influenza vaccines are required to avoid a crisis in health care. A targeted approach will develop vaccines that can reverse these age-related changes in T-cell responses, particularly the functions of cytotoxic T lymphocytes.

Integration of clinical data, pathology, and cDNA microarrays in influenza virus-infected pigtailed macaques (Macaca nemestrina)

For most severe viral pandemics such as influenza and AIDS, the exact contribution of individual viral genes to pathogenicity is still largely unknown. A necessary step toward that understanding is a systematic comparison of different influenza virus strains at the level of transcriptional regulation in the host as a whole and interpretation of these complex genetic changes in the context of multifactorial clinical outcomes and pathology. We conducted a study by infecting pigtailed macaques (Macaca nemestrina) with a genetically reconstructed strain of human influenza H1N1 A/Texas/36/91 virus and hypothesized not only that these animals would respond to the virus similarly to humans, but that gene expression patterns in the lungs and tracheobronchial lymph nodes would fit into a coherent and complete picture of the host-virus interactions during infection. The disease observed in infected macaques simulated uncomplicated influenza in humans. Clinical signs and an antibody response appeared with induction of interferon and B-cell activation pathways, respectively. Transcriptional activation of inflammatory cells and apoptotic pathways coincided with gross and histopathological signs of inflammation, with tissue damage and concurrent signs of repair. Additionally, cDNA microarrays offered new evidence of the importance of cytotoxic T cells and natural killer cells throughout infection. With this experiment, we confirmed the suitability of the nonhuman primate model in the quest for understanding the individual and joint contributions of viral genes to influenza virus pathogenesis by using cDNA microarray technology and a reverse genetics approach.

Influenza-induced tachypnea is prevented in immune cotton rats, but cannot be treated with an anti-inflammatory steroid or a neuraminidase inhibitor

Influenza viruses are one of the leading causes of morbidity and mortality during winter months. Increased respiratory rate (tachypnea) is a sign of increasing lower respiratory disease during influenza infection and is frequently observed in hospitalized patients. We investigated this clinical sign in influenza virus-infected cotton rats (Sigmodon hispidus) and the efficacy of antiviral and anti-inflammatory therapy in reducing symptomatic disease. Cotton rats infected intranasally with A/Wuhan/359/95 (H3N2) had increased respiratory rates from 1 to 4 days postinfection that correlated with the dose of virus used to inoculate the animal but not the amount of virus recovered from the lung. In addition, evaluation of sequential lung tissue pathology revealed that extensive epithelial cell destruction of small airways correlated with tachypnea. Increased respiratory rate was not observed in immune animals, supporting results that demonstrated a requirement for exposure to, and infection by, large amounts of live virus for induction of tachypnea. A variety of therapeutic approaches proved ineffective in reducing tachypnea, including anti-inflammatory therapy with systemic triamcinolone acetonide, bronchodilatory therapy with levalbuterol, or antiviral therapy with zanamivir. These results, together with the pathologic observations, suggest that early disruption of the lower respiratory tract epithelium is a major component of the pathophysiology of influenza infection. Therapeutic approaches need to be tailored to clear airway obstruction and restore an intact epithelium.

Zanamivir: a review of clinical safety in individuals at high risk of developing influenza-related complications

Post-marketing experience shows zanamivir to be well tolerated in the general population for the treatment and prophylaxis of influenza type A and B infections. Individuals at high-risk of influenza have potentially more to gain from zanamivir therapy. We assessed safety and tolerability findings from treatment and prophylaxis studies in over 982 high-risk subjects. Eight treatment studies involving high-risk subjects have been conducted with zanamivir 10 mg twice daily for 5 days. The incidence and pattern of adverse events was similar in zanamivir and placebo recipients. Lower respiratory adverse events reported by recipients receiving zanamivir occurred at similar or lower frequencies to those receiving placebo. In one treatment study involving 525 patients with asthma or chronic obstructive pulmonary disease, zanamivir recipients had a small but significantly increased mean morning peak expiratory flow rate (PEFR) and evening PEFR compared with placebo during the treatment period (days 1 to 5). Eight prophylaxis studies have been conducted, five in family or community settings and three in nursing homes. Data from these studies demonstrate that zanamivir is well tolerated for prophylaxis. In nursing home studies, where 90% of participants were high risk, the pattern and incidence of adverse events were similar to that reported in otherwise healthy individuals, and similar to both placebo and rimantadine, a comparator in one study. In treatment and prophylaxis studies the incidence and pattern of adverse events in participants > or =65 years or with chronic underlying respiratory disorders was similar for zanamivir or placebo recipients. Overall, zanamivir was well tolerated and study drug discontinuations were low. A small number of deaths have been reported in studies of high-risk elderly individuals, but none were considered to be related to zanamivir. Thus clinical studies have demonstrated that zanamivir has a comparable safety profile in high-risk and otherwise healthy recipients. Approximately 1.72 million treatment courses of zanamivir were prescribed up to the end of January 2001. Many spontaneous adverse event reports received since marketing, a third of these from non-healthcare professionals, reflect the underlying condition being treated. However, a number of events have resulted in changes to the zanamivir prescribing information, including rare reports of bronchospasm, dyspnoea, rash, urticaria and allergic type reactions including facial and oropharyngeal oedema. The reported safety profile of zanamivir, for treatment and prophylaxis of high risk subjects with influenza type A and B infections supports its continued use in these individuals who are likely to benefit most.

Deletion allele of the angiotensin-converting enzyme gene as a risk factor for pneumonia in elderly patients

PURPOSE

Aspiration due to an age-related reduction in cough is a major cause of pneumonia in elderly persons. Because the insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene (ACE) has been associated with the cough reflex, we studied whether this genetic polymorphism was also associated with the risk of pneumonia.

SUBJECTS AND METHODS

We studied 1011 elderly inpatients (221 men and 790 women, mean [+/- SD] age of 82 +/- 7 years) in a long-term care hospital. The association between the ACE I/D polymorphism and the incidence of pneumonia (defined using specific criteria that included radiographic abnormalities) was assessed during an 8-month period that excluded the winter. Data were analyzed using proportional hazards models, with adjustment for age, sex, and other potential confounders.

RESULTS

During follow-up, 87 cases (9%) of pneumonia occurred, 38 of which were fatal. The ACE DD allele (vs. ID + II) was associated with an increased risk of pneumonia (relative risk [RR] = 2.9; 95% confidence interval [CI]: 1.7 to 4.8, P < 0.001) and fatal pneumonia [RR = 4.4; 95% CI: 2.1 to 9.0; P < 0.0001).

CONCLUSIONS

The ACE D allele is an independent risk factor for pneumonia in elderly persons.

Outbreak of influenza type A (H1N1) in Iporanga, São Paulo State, Brazil

From June to July 1999 an outbreak of acute respiratory illness occurred in the town of Iporanga. Out of a total of 4,837 inhabitants, 324 cases were notified to the Regional Surveillance Service. Influenza virus was isolated from 57.1% of the collected samples and 100% seroconversion to influenza A (H1N1) was obtained in 20 paired sera tested. The isolates were related to the A/Bayern/07/95 strain (H1N1). The percentages of cases notified during the outbreak were 28.4%, 29.0%, 20.7%, 6.2% and 15.7% in the age groups of 0-4, 5-9, 10-14, 15-19 and older than 20 years, respectively. The highest proportion of positives was observed among children younger than 14 years and no cases were notified in people older than 65 years, none of whom had been recently vaccinated against influenza. These findings suggest a significant vaccine protection against A/Bayern/7/95, the H1 component included in the 1997-98 influenza vaccine for elderly people. This viral strain is antigenically and genetically related to A/Beijing/262/95, the H1 component of the 1999 vaccine. Vaccines containing A/Beijing/262/95 (H1N1) stimulated post-immunization hemagglutination inhibition antibodies equivalent in frequency and titre to both A/Beijing/262/95-like and A/Bayern/7/95-like viruses. Thus, this investigation demonstrates the effectiveness of vaccination against influenza virus in the elderly.

Anti-influenza drugs and neuraminidase inhibitors

Each year, influenza viruses are responsible for considerable illness, complications and mortality. An effective treatment will have a major impact on the severe personal and economic burden that this disease incurs. There are several points in the influenza life cycle that may be potentially inhibited. One critical point is the release of newly synthesized virions from the host cell surface. Viral neuraminidase (NA) cleaves the virus from host cell sialic acid residues allowing infection of other host cells. Rationally designed NA inhibitors that block the viral life cycle are now in the clinic and these molecules are effective and safe for the treatment of influenza. Compared with other anti-influenza agents the NA inhibitors are well tolerated, effective against all influenza types and there has been little evidence of the emergence of viral resistance. NA inhibitors provide an important new therapeutic weapon for the management of influenza infection.

Anti-influenza drugs and neuraminidase inhibitors

Each year, influenza viruses are responsible for considerable illness, complications and mortality. An effective treatment will have a major impact on the severe personal and economic burden that this disease incurs. There are several points in the influenza life cycle that may be potentially inhibited. One critical point is the release of newly synthesized virions from the host cell surface. Viral neuraminidase (NA) cleaves the virus from host cell sialic acid residues allowing infection of other host cells. Rationally designed NA inhibitors that block the viral life cycle are now in the clinic and these molecules are effective and safe for the treatment of influenza. Compared with other anti-influenza agents the NA inhibitors are well tolerated, effective against all influenza types and there has been little evidence of the emergence of viral resistance. NA inhibitors provide an important new therapeutic weapon for the management of influenza infection.

Immune responses and protection in different strains of aged mice immunized intranasally with an adjuvant-combined influenza vaccine

Immune responses and protection against influenza virus infection were compared between young (2 months) and aged (18 months) BALB/c, C3H and C57BL/6 (B6) mice after intranasal vaccination. The mice were immunized with 2.5 microg protein of A/PR/8/34 (PR8) (H1N1) virus vaccine containing a cholera toxin adjuvant. In both the young and aged BALB/c mice, high levels of PR8-specific antibody-forming cell (AFC) responses were induced in the nasal-associated lymphoid tissue (NALT) 7 days after immunization. Nasal wash IgA and serum IgG antibody (Ab) responses to the PR8 haemagglutinin (HA) 4 weeks after immunization were slightly higher in the young mice than in the aged mice. The young mice showed complete protection against challenge infection, while the aged mice showed only a partial protection. In the C3H mice, NALT-AFC, and IgA and IgG Ab responses were higher in the young mice than those in the aged mice in parallel with the more efficient protection in the young mice than in the aged mice. Both the young and aged B6 mice showed no NALT-AFC responses, scarce IgA and IgG Ab responses and no protection. In the BALB/c mice, IgG1 and IgG2a levels were significantly lower in the aged mice. On the other hand, in the C3H mice, only IgG2a level was significantly lower in the aged mice. Similar results were obtained in terms of immune responses and protection between the young and aged mice of three different strains of mice after intra-nasal immunization with 0.1 microg of PR8 vaccine containing the adjuvant, two-times at 4-week intervals. In the B6 mice, the immune response was improved by immunization with a higher dose of the adjuvant-combined vaccine. These results suggest that local Ab responses, as well as systemic Ab responses, are downregulated in aged mice, although the degree of the downregulation of immune responses differs from strain to strain.

The adjuvanted influenza vaccines with novel adjuvants: experience with the MF59-adjuvanted vaccine

Elderly people and subjects with underlying chronic diseases are at increased risk for influenza and related complications. Conventional influenza vaccines provide only limited protection in the elderly population. In order to enhance the immune response to influenza vaccines, several adjuvants have been evaluated. Among these, an oil in water adjuvant emulsion containing squalene, MF59, has been combined with subunit influenza antigens and tested in clinical trials in comparison with non-adjuvanted conventional vaccines. Data from a clinical database of over 10000 elderly subjects immunised with this adjuvanted vaccine (Fluad, Chiron Vaccines, Siena, Italy) demonstrate that, although common postimmunisation reactions are more frequent in recipients of the adjuvanted vaccine, this vaccine is well tolerated, also after re-immunisation in subsequent influenza seasons. Immunogenicity analyses demonstrate a consistently higher immune response with statistically significant increases of postimmunisation geometric mean titres, and of seroconversion and seroprotection rates compared to non-adjuvanted subunit and split influenza vaccines, particularly for the A/H3N2 and the B strains. The higher immunogenicity profile of the MF59-adjuvanted vaccine is maintained also after subsequent immunisations. An even higher adjuvant effect was shown in subjects with low pre-immunisation titre and in those affected by chronic underlying diseases. In conclusion, the addition of MF59 to subunit influenza vaccines enhances significantly the immune response in elderly subjects without causing clinically important changes in the safety profile of the influenza vaccine.

Immunogenicity and safety of three commercial influenza vaccines in institutionalized elderly

Influenza is a leading cause of morbidity and mortality in elderly people. This prospective, observed-blind, randomized, multicenter trial compares the immunogenicity and safety of three influenza vaccines in a sample of 635 elderly residents of four nursing homes in Milano (Italy). All vaccines were well tolerated: no serious adverse events were recorded, and a small number (9 subjects) of local and systemic reactions were observed. Twenty-nine oropharyngeal swabs were taken during the season from ILI (influenza-like illness) patients, none of whom was positive for influenza and other respiratory viruses. Immunogenicity was evaluated in a subgroup of 111 subjects with blood samples obtained just before vaccination and after 4 and 12 weeks. The adjuvanted vaccines, subunit vaccine with MF59 (a-SUV) and virosome subunit vaccine (v-SUV), induced a higher antibody response than whole virus vaccine (WVV). There was no significant difference between groups that received a-SUV and v-SUV, but the a-SUV group had higher values of geometric mean titres than the v-SUV group for H1N1 and B influenza strains. These findings suggest that influenza vaccination is effective, and they underscore the importance of vaccination programs for institutionalized elderly. Further studies are needed to compare other adjuvanted vaccines in order to define their different properties.

Immune response to influenza vaccine in healthy elderly: lack of association with plasma beta-carotene, retinol, alpha-tocopherol, or zinc

Immunity and nutritional status are compromised with age, yet the relationship between them is unclear. Immune responses and plasma micronutrient levels of 61 healthy elderly (mean 81 years) and 27 young (mean 27 years) were assessed before and after immunization with trivalent influenza vaccine (FLU). FLU-induced proliferation and IFN-gamma levels of elderly were lower than young before and after immunization. Proliferation and IFN-gamma levels increased after immunization of young, but not elderly. FLU-induced IL-6 and IL-10 levels did not change after immunization of either group. While antibody titers to all three FLU components increased after vaccination of young and elderly, post-vaccination titers of elderly were lower than young. Although plasma retinol and zinc levels of young and elderly were similar before and after vaccination, elderly had higher plasma beta-carotene and alpha-tocopherol levels at both assessments that increased after vaccination. Importantly, plasma micronutrient levels were comparable for elderly with or without intact (titers >/=40 and fourfold rise post-vaccination) antibody responses after vaccination. These results suggest that differences in these plasma micronutrients (1) are not required to observe decreased FLU responses of healthy elderly compared to young and (2) are not associated with differences in antibody responses among healthy elderly.