Does influenza vaccination prevent asthma exacerbations in children?

Effect of Tezepelumab on the Humoral Immune Response to Seasonal Quadrivalent Influenza Vaccination in Patients with Moderate to Severe Asthma: The Phase 3b VECTOR Study

INTRODUCTION

Annual influenza vaccinations are recommended for adolescents and adults with moderate to severe asthma. This study investigated the effect of tezepelumab, a human monoclonal antibody that blocks the activity of thymic stromal lymphopoietin, on the humoral immune response to the quadrivalent seasonal influenza vaccine in patients with moderate to severe asthma.

METHODS

VECTOR was a phase 3b, randomized, multicenter, double-blind, parallel-group, placebo-controlled study. Adolescents (aged 12-17 years) and young adults (aged 18-21 years) with moderate to severe asthma were enrolled across 15 centers in the USA. Patients received tezepelumab 210 mg or placebo subcutaneously at weeks 0, 4, 8, and 12, and a single dose of inactivated quadrivalent seasonal influenza vaccine at week 12 before receiving study treatment. Immediately before vaccination and at 4 weeks postvaccination (week 16), strain-specific antibody responses were assessed for four influenza antigens by hemagglutination inhibition (HAI) and microneutralization (MN) assays. Safety was assessed.

RESULTS

Seventy patients were randomized to tezepelumab (n = 35) or placebo (n = 35). There were no meaningful differences in HAI or MN antibody responses between treatment groups at week 16. HAI assay geometric mean fold rises (GMFRs) for influenza strains were 1.76-7.34 for tezepelumab and 1.46-4.75 for placebo. MN assay GMFRs were 4.00-14.56 for tezepelumab and 3.56-10.62 for placebo. In the HAI assay, a fourfold or larger rise in antibody titer from weeks 12 to 16 occurred in 15.2-78.8% and 15.2-51.5% of tezepelumab and placebo recipients, respectively, and 97.0-100% of patients in both treatment groups achieved an antibody titer of at least 40 at week 16. No unexpected safety findings occurred.

CONCLUSION

There was no observed suppression of the humoral immune response after influenza vaccination in adolescents and young adults with moderate to severe asthma treated with tezepelumab. Therefore, the influenza vaccine can be administered to this patient population during tezepelumab treatment.

CLINICALTRIALS

GOV IDENTIFIER

NCT05062759.

Pediatric asthma exacerbation and COVID-19 pandemic: Impacts, challenges, and future considerations

OBJECTIVE

Asthma, a common disease among children and adolescents, poses a great health risk when ignored; therefore, a thorough follow-up to prevent exacerbations is emphasized. The aim of the present study is to investigate asthma exacerbation in children during the Coronavirus disease 2019 (COVID-19) era.

DATA SOURCES

This narrative review has been done by searching the PubMed and Embase databases using Asthma, COVID-19, Pandemic, and Symptom flare up as keywords.

STUDY SELECTIONS

Studies related to asthma exacerbation in COVID-19 pandemic were included.

RESULTS

Based on studies, controlled or mild to moderate asthma has not been considered a risk factor for COVID-19 severity and has not affected hospitalization, intensive care unit (ICU) admission, and mortality. Surprisingly, emergent and non-emergent visits and asthmatic attacks decreased during the pandemic. The three main reasons for decreased incidence and exacerbation of asthma episodes in the COVID-19 era included reduced exposure to environmental allergens, increasing the acceptance of treatment by pediatrics and caregivers, and decreased risk of other respiratory viral infections. Based on the available studies, COVID-19 vaccination had no serious side effects, except in cases of uncontrolled severe asthma, and can be injected in these children. Also, there was no conclusive evidence of asthma exacerbation after the injection of COVID-19 vaccines.

CONCLUSION

Further studies are recommended to follow the pattern of asthma in the post-pandemic situation and to become prepared for similar future conditions.

Maintenance Therapy for Children and Adolescents with Asthma: Guidelines and Recommendations from the Emilia-Romagna Asthma (ERA) Study Group

Asthma is the most frequent chronic disease of childhood, affecting up to 20% of children worldwide. The main guidelines on asthma maintenance therapy in pediatrics suggest different approaches and describe different stages of asthma to determine the most appropriate treatment. This project aims to summarize the most recent evidence regarding maintenance therapy for asthma in children and adolescents. A multidisciplinary panel of experts was asked clinical questions regarding the treatment of children and adolescents with asthma. Overall, 10 clinical questions were addressed, and the search strategy included accessing electronic databases and a manual search of gray literature published in the last 25 years. After data extraction and narrative synthesis of results, recommendations were developed using the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) methodology. Results showed that the choice of medication depends on the severity of the child's asthma, phenotype, age, preference, and individual factors. In addition to medications, the identification of comorbidities and modifiable factors is crucial to obtaining good control. Asthma in children is heterogeneous, and its evolution varies over time. Since most recommendations for asthma management in childhood are extrapolated from clinical studies performed in adults, more clinical trials specifically designed for young children should be conducted.

Whispers of change in preschool asthma phenotypes: Findings in the French ELFE cohort

RATIONALE

Early life asthma phenotyping remains an unmet need in pediatric asthma. In France, severe pediatric asthma phenotyping has been done extensively; however, phenotypes in the general population remain underexplored. Based on the course and severity of respiratory/allergic symptoms, we aimed to identify and characterize early life wheeze profiles and asthma phenotypes in the general population.

METHODS

ELFE is a general population based birth cohort; which recruited 18,329 newborns in 2011, from 320 maternity units nationwide. Data was collected using parental responses to modified versions of ISAAC questionnaire on eczema, rhinitis, food allergy, cough, wheezing, dyspnoea and sleep disturbance due to wheezing at 3 time points: post-natal (2 months), infancy (age 1) and pre-school (age 5). We built a supervised trajectory for wheeze profiles and an unsupervised approach was used for asthma phenotypes. Chi squared (χ2) test or fisher's exact test was used as appropriate (p < 0.05).

RESULTS

Wheeze profiles and asthma phenotypes were ascertained at age 5. Supervised wheeze trajectory of 9161 children resulted in 4 wheeze profiles: Persistent (0.8%), Transient (12.1%), Incident wheezers at age 5 (13.3%) and Non wheezers (73.9%). While 9517 children in unsupervised clusters displayed 4 distinct asthma phenotypes: Mildly symptomatic (70%), Post-natal bronchiolitis with persistent rhinitis (10.2%), Severe early asthma (16.9%) and Early persistent atopy with late onset severe wheeze (2.9%).

CONCLUSION

We successfully determined early life wheeze profiles and asthma phenotypes in the general population of France.

Current Approaches to Vaccine Safety Using Observational Data: A Rationale for the EUMAEUS (Evaluating Use of Methods for Adverse Events Under Surveillance-for Vaccines) Study Design

Post-marketing vaccine safety surveillance aims to detect adverse events following immunization in a population. Whether certain methods of surveillance are more precise and unbiased in generating safety signals is unclear. Here, we synthesized information from existing literature to provide an overview of the strengths, weaknesses, and clinical applications of epidemiologic and analytical methods used in vaccine monitoring, focusing on cohort, case-control and self-controlled designs. These designs are proposed to be evaluated in the EUMAEUS (Evaluating Use of Methods for Adverse Event Under Surveillance-for vaccines) study because of their widespread use and potential utility. Over the past decades, there have been an increasing number of epidemiological study designs used for vaccine safety surveillance. While traditional cohort and case-control study designs remain widely used, newer, novel designs such as the self-controlled case series and self-controlled risk intervals have been developed. Each study design comes with its strengths and limitations, and the most appropriate study design will depend on availability of resources, access to records, number and distribution of cases, and availability of population coverage data. Several assumptions have to be made while using the various study designs, and while the goal is to mitigate any biases, violations of these assumptions are often still present to varying degrees. In our review, we discussed some of the potential biases (i.e., selection bias, misclassification bias and confounding bias), and ways to mitigate them. While the types of epidemiological study designs are well established, a comprehensive comparison of the analytical aspects (including method evaluation and performance metrics) of these study designs are relatively less well studied. We summarized the literature, reporting on two simulation studies, which compared the detection time, empirical power, error rate and risk estimate bias across the above-mentioned study designs. While these simulation studies provided insights on the analytic performance of each of the study designs, its applicability to real-world data remains unclear. To bridge that gap, we provided the rationale of the EUMAEUS study, with a brief description of the study design; and how the use of real-world multi-database networks can provide insights into better methods evaluation and vaccine safety surveillance.

Self-controlled case series design in vaccine safety: a systematic review

BACKGROUND

: An increasing number of vaccine safety studies using the self-controlled case-series (SCCS) design have been conducted in the last decade. However, there has been no comprehensive evaluation of the methodology and reporting quality of these observational studies. The purpose of this paper is to document the methodological features of studies that focused on vaccine safety using the SCCS design, and to evaluate the reporting quality of these studies to suggest future improvements on appropriate design and transparent reporting.

METHODS

: Databases including Medline, Embase, Web of Science, Scopus and Chinese databases were searched from inception to May 31, 2021. All observational studies regarding vaccine safety using a SCCS design were selected. Information regarding methodological elements were extracted. In addition, reporting quality was assessed using the REporting of studies Conducted using Observational Routinely collected health Data statement for PharmacoEpidemiology (RECORD-PE).

RESULTS

: Of the 105 studies identified, administrative databases were the main data source for vaccination records and adverse events following immunization (AEFI). 28 articles (27%) used multiple designs to verify the association, and the results obtained with the SCCS design were robust. The top three AEFI studied were intussusception, Guillain-Barré syndrome, and convulsions. Only 21 studies (20%) reported the approach for case validation by chart review. The healthy vaccinee effect was considered by 51studies (49%), with 16 of them (31%) using extended SCCS models to alleviate this effect. Overall, the reporting quality of included studies could be improved.

CONCLUSIONS

: This study systematically reviewed the methodology of studies regarding vaccine safety using a SCCS design and critically assessed their respective reporting quality. Case validation, the validity of assumptions for standard SCCS, and quality of reporting should be given more importance in future research projects.

Recommendations of the Italian society for infectious and tropical diseases (SIMIT) for adult vaccinations

Vaccination prevents 2-3 million deaths worldwide every year. Nevertheless, vaccine-preventable diseases (VPDs) still cause a considerable number of deaths especially in subjects belonging to "risk groups." These are represented by older adults, immunocompromised individuals and all subjects with underlying chronic medical conditions (cardiovascular, pulmonary, renal and liver chronic diseases, diabetes, immunodeficiency disorders). They have a weaker immune system and, if infected, are more likely to develop severe complications of their condition or of the preventable-infectious disease. This document summarizes the recommendations for vaccination of the main Global Institutional Organizations and analyses the risks of comorbidities associated with infectious disease and the benefits of vaccination for each specific group. The document provides a clear, practical and authoritative guide to adult vaccination.

Influenza epidemics: The role of allergists-immunologists

OBJECTIVE

To review influenza epidemics and pandemics for practicing allergists-immunologists.

DATA SOURCES

English-language articles published in PubMed from 1990 to present with relevance to allergic disorders and articles cited by or similar to these articles.

STUDY SELECTIONS

A total of 472 articles were identified from PubMed. Two independent reviewers appraised the titles for relevance.

RESULTS

A total of 212 relevant articles were selected. Additional articles and government websites increased the number to 295 relevant citations.

CONCLUSION

Influenza epidemics and pandemics have recurred throughout history. Patients with asthma and immunodeficiency are at an increased risk. Nonpharmaceutical interventions, vaccination, and neuraminidase inhibitors are key strategies for the prevention and treatment of influenza epidemics/pandemics. Allergists play a vital role in protecting high-risk groups and increasing influenza vaccination coverage.

Serious outcomes of medically attended, laboratory-confirmed influenza illness among school-aged children with and without asthma, 2007-2018

Background

Asthma was associated with influenza hospitalizations in children during the 2009 pandemic, but it is unclear if asthma is associated with serious illness during seasonal epidemics. Little is known regarding the effect of vaccination on influenza severity in children with asthma.

Methods

Children aged 5‐17 years in a community cohort presenting with acute respiratory illness were prospectively enrolled and tested for influenza from 2007‐08 through 2017‐18 (excluding the 2009‐10 pandemic season). Data from the electronic health record were extracted to determine asthma status and serious outcomes associated with influenza infection. A serious outcome was defined as hospitalization, emergency department visit, and/or pneumonia diagnosis within 30 days of symptom onset. Multivariable logistic regression models were used to assess asthma status and effect of vaccination on odds of a serious outcome.

Results

One thousand seven hundred and sixty four medically‐attended influenza infections among school‐aged children were included. Asthma was confirmed in 287 (16%) children. A serious influenza‐associated outcome occurred in 104 (6%) children. The odds of a serious outcome did not differ between those with confirmed asthma and those without asthma [adjusted odds ratio (aOR): 1.35, 95% confidence interval (CI): (0.77‐2.35), P = .3]. The effect of vaccination on serious outcomes was not modified by asthma status [aOR for children without asthma: 0.55 (95% CI: 0.28‐1.07), children with asthma: 1.39 (95% CI: 0.53‐3.69); interaction P‐value = .12].

Conclusions

Asthma was not a risk factor for serious illness among children with influenza. Additional studies are needed to better understand the role of influenza vaccination in preventing serious outcomes among children with asthma.

Benefits of influenza vaccination on the associations between ambient air pollution and allergic respiratory diseases in children and adolescents: New insights from the Seven Northeastern Cities study in China

BACKGROUND

Little information exists on interaction effects between air pollution and influenza vaccination on allergic respiratory diseases. We conducted a large population-based study to evaluate the interaction effects between influenza vaccination and long-term exposure to ambient air pollution on allergic respiratory diseases in children and adolescents.

METHODS

A cross-sectional study was investigated during 2012-2013 in 94 schools from Seven Northeastern Cities (SNEC) in China. Questionnaires surveys were obtained from 56 137 children and adolescents aged 2-17 years. Influenza vaccination was defined as receipt of the influenza vaccine. We estimated air pollutants exposure [nitrogen dioxide (NO₂) and particulate matter with aerodynamic diameters ≤1 μm (PM₁), ≤2.5 μm (PM_2.5) and ≤10 μm (PM₁₀)] using machine learning methods. We employed two-level generalized linear mix effects model to examine interactive effects between influenza vaccination and air pollution exposure on allergic respiratory diseases (asthma, asthma-related symptoms and allergic rhinitis), after controlling for important covariates.

RESULTS

We found statistically significant interactions between influenza vaccination and air pollutants on allergic respiratory diseases and related symptoms (doctor-diagnosed asthma, current wheeze, wheeze, persistent phlegm and allergic rhinitis). The adjusted ORs for doctor-diagnosed asthma, current wheeze and allergic rhinitis among the unvaccinated group per interquartile range (IQR) increase in PM₁ and PM_2.5 were significantly higher than the corresponding ORs among the vaccinated group [For PM₁, doctor-diagnosed asthma: OR: 1.89 (95%CI: 1.57-2.27) vs 1.65 (95%CI: 1.36-2.00); current wheeze: OR: 1.50 (95%CI: 1.22-1.85) vs 1.10 (95%CI: 0.89-1.37); allergic rhinitis: OR: 1.38 (95%CI: 1.15-1.66) vs 1.21 (95%CI: 1.00-1.46). For PM_2.5, doctor-diagnosed asthma: OR: 1.81 (95%CI: 1.52-2.14) vs 1.57 (95%CI: 1.32-1.88); current wheeze: OR: 1.46 (95%CI: 1.21-1.76) vs 1.11 (95%CI: 0.91-1.35); allergic rhinitis: OR: 1.35 (95%CI: 1.14-1.60) vs 1.19 (95%CI: 1.00-1.42)]. The similar patterns were observed for wheeze and persistent phlegm. The corresponding p values for interactions were less than 0.05, respectively. We assessed the risks of PM₁-related and PM_2.5-related current wheeze were decreased by 26.67% (95%CI: 1.04%-45.66%) and 23.97% (95%CI: 0.21%-42.08%) respectively, which was attributable to influenza vaccination (both p for efficiency <0.05).

CONCLUSIONS

Influenza vaccination may play an important role in mitigating the detrimental effects of long-term exposure to ambient air pollution on childhood allergic respiratory diseases. Policy targeted at increasing influenza vaccination may yield co-benefits in terms of reduced allergic respiratory diseases.

Temporal and spatial associations between influenza and asthma hospitalisations in New York City from 2002 to 2012: a longitudinal ecological study

OBJECTIVES

To determine whether asthma hospitalisations of children and adults in the five boroughs of New York City are correlated with influenza hospitalisations temporally and spatially.

DESIGN

A longitudinal ecological study.

INCLUSION CRITERIA

We reviewed the Statewide Planning and Research Cooperative System's records of hospitalisations in Manhattan, Bronx, Queens, Brooklyn and Staten Island from 2002 to 2012. All hospitalisations with a primary diagnosis of either asthma or influenza were identified using the International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis codes.

METHODS

A time-series regression analysis was performed using aggregate monthly counts of influenza hospitalisations as predictors of asthma hospitalisations. Time-series regression models were also applied to different age groups and boroughs to examine the magnitude of influenza and asthma correlations across strata. The per cent excess risk was also calculated across age groups and boroughs.

RESULTS

Time-series analysis of the overall population revealed a significant positive correlation between influenza and asthma hospitalisations (p=0.011). When stratifying by age, there was a significant positive correlation between asthma and influenza hospitalisations for individuals 18 and older (p<0.01), and no significant correlation found for age groups younger than 18. Percentages of excess risk of influenza-related asthma hospitalisations also increased with increasing age with adults 18-44, 45-64 and 65+ having excess risk percentages of 2.9%, 3.4% and 4%, respectively. Time-series analysis by location revealed positive significant correlations between asthma and influenza hospitalisations in Brooklyn (p=0.03) and Manhattan (p<0.01). Manhattan and Brooklyn had a 2.5% and 1.6%, respectively, percentage of excess risk of influenza-related asthma hospitalisations.

CONCLUSION

Influenza and asthma hospitalisations are significantly associated at the population level among adults. These associations vary by age and geographical location. Influenza prevention strategies targeting adult populations, particularly individuals living in Manhattan and Brooklyn, have the potential for meaningful reduction of influenza-related asthma hospitalisations.

Influenza burden, prevention, and treatment in asthma-A scoping review by the EAACI Influenza in asthma task force

To address uncertainties in the prevention and management of influenza in people with asthma, we performed a scoping review of the published literature on influenza burden; current vaccine recommendations; vaccination coverage; immunogenicity, efficacy, effectiveness, and safety of influenza vaccines; and the benefits of antiviral drugs in people with asthma. We found significant variation in the reported rates of influenza detection in individuals with acute asthma exacerbations making it unclear to what degree influenza causes exacerbations of underlying asthma. The strongest evidence of an association was seen in studies of children. Countries in the European Union currently recommend influenza vaccination of adults with asthma; however, coverage varied between regions. Coverage was lower among children with asthma. Limited data suggest that good seroprotection and seroconversion can be achieved in both children and adults with asthma and that vaccination confers a degree of protection against influenza illness and asthma-related morbidity to children with asthma. There were insufficient data to determine efficacy in adults. Overall, influenza vaccines appeared to be safe for people with asthma. We identify knowledge gaps and make recommendations on future research needs in relation to influenza in patients with asthma.

Distinction between rhinovirus-induced acute asthma and asthma-augmented influenza infection

BACKGROUND

Rhinovirus (RV) is an established trigger of asthma attacks, whereas such a link is less consistent for influenza virus (IFV).

OBJECTIVE

In the context of precision medicine, we hypothesized that IFV infection may cause a condition essentially different from RV, and we investigated this by evaluating clinical characteristics of RV/IFV-positive and -negative children with respiratory symptoms and/or fever.

METHODS

One thousand two hundred and seven children, 6 months to 13 years old, hospitalized for flu-like illness were recruited in this cross-sectional study. Collected information included demographics, medical history, symptoms/physical findings/diagnosis at presentation and treatment. Nasal secretions were PCR-tested for IFV/RV. Associations were evaluated with adjusted logistic regression models.

RESULTS

Rhinovirus positivity was associated with an asthma-like presentation, including increased wheeze/effort of breathing/diagnosis of acute asthma, and decreased fever/vomiting. Conversely, IFV⁺ children presented with less wheeze/effort of breathing/diagnosis of acute asthma, while they were more frequently febrile. In those with previous asthma history, both viruses induced wheeze; however, IFV was uniquely associated with a more generalised and severe presentation including fever, rales, intercostal muscle retractions and lymphadenopathy. These symptoms were not seen in RV⁺ asthmatics, who had fewer systemic signs and more cough.

CONCLUSIONS AND CLINICAL RELEVANCE

In children with respiratory symptoms and/or fever, RV but not IFV is associated with wheeze and an asthma-like presentation. In those with an asthma history, IFV causes more generalised and severe disease that may be better described as "asthma-augmented influenza" rather than an "asthma attack." Differences in the acute conditions caused by these viruses should be considered in the design of epidemiological studies.

Effectiveness of live attenuated influenza vaccine in preventing amoxicillin prescribing in preschool children: a self-controlled case series study

Objectives

To determine the effectiveness of live attenuated influenza vaccine (LAIV) in reducing amoxicillin prescribing in preschool children in primary care.

Patients and methods

We used The Health Improvement Network (THIN), a large primary care database from the United Kingdom. We included children aged 2 to 4 years old at the start of either the 2013/14 or the 2014/15 winter season, with at least one amoxicillin prescription between September and May, irrespective of LAIV vaccination status. We used the self-controlled case series method to estimate influenza vaccine effectiveness (VE).

Results

The total study sample included 33 137 children from 378 general practices during the two winter seasons. Of these children, 43.4% with at least one amoxicillin prescription had been vaccinated. The rate of amoxicillin prescribing was significantly reduced during periods of influenza vaccine immunity. The associated VE for amoxicillin prescribing was 12.8% (95% CI 6.9%, 18.3%) in 2013/14 and 14.5% (9.6%, 19.2%) in 2014/15. Given a VE of 14.5%, we estimated that amoxicillin prescribing could have been reduced by 5.6% if LAIV uptake in children aged 2-4 years increased to 50% in the 2014/15 winter season.

Conclusions

Influenza vaccination of young children may contribute to a reduction in the prescribing of amoxicillin, one of the most commonly prescribed antibiotics in primary care. Further studies are required to confirm the size of the effect.

Vaccines for preventing influenza in healthy children

BACKGROUND

The consequences of influenza in children and adults are mainly absenteeism from school and work. However, the risk of complications is greatest in children and people over 65 years of age. This is an update of a review published in 2011. Future updates of this review will be made only when new trials or vaccines become available. Observational data included in previous versions of the review have been retained for historical reasons but have not been updated because of their lack of influence on the review conclusions.

OBJECTIVES

To assess the effects (efficacy, effectiveness, and harm) of vaccines against influenza in healthy children.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library 2016, Issue 12), which includes the Cochrane Acute Respiratory Infections Group Specialised Register, MEDLINE (1966 to 31 December 2016), Embase (1974 to 31 December 2016), WHO International Clinical Trials Registry Platform (ICTRP; 1 July 2017), and ClinicalTrials.gov (1 July 2017).

SELECTION CRITERIA

Randomised controlled trials comparing influenza vaccines with placebo or no intervention in naturally occurring influenza in healthy children under 16 years. Previous versions of this review included 19 cohort and 11 case-control studies. We are no longer updating the searches for these study designs but have retained the observational studies for historical purposes.

DATA COLLECTION AND ANALYSIS

Review authors independently assessed risk of bias and extracted data. We used GRADE to rate the certainty of evidence for the key outcomes of influenza, influenza-like illness (ILI), complications (hospitalisation, ear infection), and adverse events. Due to variation in control group risks for influenza and ILI, absolute effects are reported as the median control group risk, and numbers needed to vaccinate (NNVs) are reported accordingly. For other outcomes aggregate control group risks are used.

MAIN RESULTS

We included 41 clinical trials (> 200,000 children). Most of the studies were conducted in children over the age of two and compared live attenuated or inactivated vaccines with placebo or no vaccine. Studies were conducted over single influenza seasons in the USA, Western Europe, Russia, and Bangladesh between 1984 and 2013. Restricting analyses to studies at low risk of bias showed that influenza and otitis media were the only outcomes where the impact of bias was negligible. Variability in study design and reporting impeded meta-analysis of harms outcomes.Live attenuated vaccinesCompared with placebo or do nothing, live attenuated influenza vaccines probably reduce the risk of influenza infection in children aged 3 to 16 years from 18% to 4% (risk ratio (RR) 0.22, 95% confidence interval (CI) 0.11 to 0.41; 7718 children; moderate-certainty evidence), and they may reduce ILI by a smaller degree, from 17% to 12% (RR 0.69, 95% CI 0.60 to 0.80; 124,606 children; low-certainty evidence). Seven children would need to be vaccinated to prevent one case of influenza, and 20 children would need to be vaccinated to prevent one child experiencing an ILI. Acute otitis media is probably similar following vaccine or placebo during seasonal influenza, but this result comes from a single study with particularly high rates of acute otitis media (RR 0.98, 95% CI 0.95 to 1.01; moderate-certainty evidence). There was insufficient information available to determine the effect of vaccines on school absenteeism due to very low-certainty evidence from one study. Vaccinating children may lead to fewer parents taking time off work, although the CI includes no effect (RR 0.69, 95% CI 0.46 to 1.03; low-certainty evidence). Data on the most serious consequences of influenza complications leading to hospitalisation were not available. Data from four studies measuring fever following vaccination varied considerably, from 0.16% to 15% in children who had live vaccines, while in the placebo groups the proportions ranged from 0.71% to 22% (very low-certainty evidence). Data on nausea were not reported.Inactivated vaccinesCompared with placebo or no vaccination, inactivated vaccines reduce the risk of influenza in children aged 2 to 16 years from 30% to 11% (RR 0.36, 95% CI 0.28 to 0.48; 1628 children; high-certainty evidence), and they probably reduce ILI from 28% to 20% (RR 0.72, 95% CI 0.65 to 0.79; 19,044 children; moderate-certainty evidence). Five children would need to be vaccinated to prevent one case of influenza, and 12 children would need to be vaccinated to avoid one case of ILI. The risk of otitis media is probably similar between vaccinated children and unvaccinated children (31% versus 27%), although the CI does not exclude a meaningful increase in otitis media following vaccination (RR 1.15, 95% CI 0.95 to 1.40; 884 participants; moderate-certainty evidence). There was insufficient information available to determine the effect of vaccines on school absenteeism due to very low-certainty evidence from one study. We identified no data on parental working time lost, hospitalisation, fever, or nausea.We found limited evidence on secondary cases, requirement for treatment of lower respiratory tract disease, and drug prescriptions. One brand of monovalent pandemic vaccine was associated with a sudden loss of muscle tone triggered by the experience of an intense emotion (cataplexy) and a sleep disorder (narcolepsy) in children. Evidence of serious harms (such as febrile fits) was sparse.

AUTHORS' CONCLUSIONS

In children aged between 3 and 16 years, live influenza vaccines probably reduce influenza (moderate-certainty evidence) and may reduce ILI (low-certainty evidence) over a single influenza season. In this population inactivated vaccines also reduce influenza (high-certainty evidence) and may reduce ILI (low-certainty evidence). For both vaccine types, the absolute reduction in influenza and ILI varied considerably across the study populations, making it difficult to predict how these findings translate to different settings. We found very few randomised controlled trials in children under two years of age. Adverse event data were not well described in the available studies. Standardised approaches to the definition, ascertainment, and reporting of adverse events are needed. Identification of all global cases of potential harms is beyond the scope of this review.

Prevention and Control of Seasonal Influenza with Vaccines

This report updates the 2015-16 recommendations of the Advisory Committee on Immunization Practices (ACIP) regarding the use of seasonal influenza vaccines (Grohskopf LA, Sokolow LZ, Olsen SJ, Bresee JS, Broder KR, Karron RA. Prevention and control of influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices, United States, 2015-16 influenza season. MMWR Morb Mortal Wkly Rep 2015;64:818-25). Routine annual influenza vaccination is recommended for all persons aged ≥6 months who do not have contraindications. For the 2016-17 influenza season, inactivated influenza vaccines (IIVs) will be available in both trivalent (IIV3) and quadrivalent (IIV4) formulations. Recombinant influenza vaccine (RIV) will be available in a trivalent formulation (RIV3). In light of concerns regarding low effectiveness against influenza A(H1N1)pdm09 in the United States during the 2013-14 and 2015-16 seasons, for the 2016-17 season, ACIP makes the interim recommendation that live attenuated influenza vaccine (LAIV4) should not be used. Vaccine virus strains included in the 2016-17 U.S. trivalent influenza vaccines will be an A/California/7/2009 (H1N1)-like virus, an A/Hong Kong/4801/2014 (H3N2)-like virus, and a B/Brisbane/60/2008-like virus (Victoria lineage). Quadrivalent vaccines will include an additional influenza B virus strain, a B/Phuket/3073/2013-like virus (Yamagata lineage).Recommendations for use of different vaccine types and specific populations are discussed. A licensed, age-appropriate vaccine should be used. No preferential recommendation is made for one influenza vaccine product over another for persons for whom more than one licensed, recommended product is otherwise appropriate. This information is intended for vaccination providers, immunization program personnel, and public health personnel. Information in this report reflects discussions during public meetings of ACIP held on October 21, 2015; February 24, 2016; and June 22, 2016. These recommendations apply to all licensed influenza vaccines used within Food and Drug Administration-licensed indications, including those licensed after the publication date of this report. Updates and other information are available at CDC's influenza website (http://www.cdc.gov/flu). Vaccination and health care providers should check CDC's influenza website periodically for additional information.

A systematic review of validated methods to capture acute bronchospasm using administrative or claims data

PURPOSE

To identify and assess billing, procedural, or diagnosis code, or pharmacy claim-based algorithms used to identify acute bronchospasm in administrative and claims databases.

METHODS

We searched the MEDLINE database from 1991 to September 2012 using controlled vocabulary and key terms related to bronchospasm, wheeze and acute asthma. We also searched the reference lists of included studies. Two investigators independently assessed the full text of studies against pre-determined inclusion criteria. Two reviewers independently extracted data regarding participant and algorithm characteristics.

RESULTS

Our searches identified 677 citations of which 38 met our inclusion criteria. In these 38 studies, the most commonly used ICD-9 code was 493.x. Only 3 studies reported any validation methods for the identification of bronchospasm, wheeze or acute asthma in administrative and claims databases; all were among pediatric populations and only 2 offered any validation statistics. Some of the outcome definitions utilized were heterogeneous and included other disease based diagnoses, such as bronchiolitis and pneumonia, which are typically of an infectious etiology. One study offered the validation of algorithms utilizing Emergency Department triage chief complaint codes to diagnose acute asthma exacerbations with ICD-9 786.07 (wheezing) revealing the highest sensitivity (56%), specificity (97%), PPV (93.5%) and NPV (76%).

CONCLUSIONS

There is a paucity of studies reporting rigorous methods to validate algorithms for the identification of bronchospasm in administrative data. The scant validated data available are limited in their generalizability to broad-based populations.

Effectiveness of an asthma quality improvement program designed for maintenance of certification

OBJECTIVE

Pediatricians are required to perform quality improvement for board recertification. We developed an asthma project within the Pediatric Physicians' Organization at Children's, an independent practice association affiliated with Boston Children's Hospital, designed to meet recertification requirements and improve asthma care.

METHODS

The program was based on the learning collaborative model. We developed practice-based registries of children 5 to 17 years of age with persistent asthma and helped physicians improve processes of asthma care through education, data feedback, and sharing of best practices.

RESULTS

Fifty-six physicians participated in 3 cohorts; 594 patients were included in the project. In all cohorts, improvements occurred in the use of asthma action plans (62.4%-76.8% cohort 1, 50.6%-88.4% cohort 2, 53.0%-79.6% cohort 3) and Asthma Control Tests (4.6%-55.2% cohort 1, 9.0%-67.8% cohort 2, 15.2%-61.4% cohort 3). Less consistent improvements were observed in seasonal influenza vaccines, controller medications, and asthma follow-up visits. The proportion of patients experiencing ≥1 asthma exacerbation within the year declined in all 3 cohorts (37.8%-19.9%, P = .0002 cohort 1; 27.8%-20.7%, P = .1 cohort 2; 36.6%-26.9%, P = .1 cohort 3). For each cohort, asthma exacerbations declined to a greater extent than those of a comparison group.

CONCLUSIONS

This asthma quality improvement project designed for maintenance of certification improved processes of care among patients with persistent asthma. The learning collaborative approach may be a useful model for other board-recertification quality improvement projects but requires a substantial investment of organizational time and staff.

Asthma in the elderly: what we know and what we have yet to know

In the past, asthma was considered mainly as a childhood disease. However, asthma is an important cause of morbidity and mortality in the elderly nowadays. In addition, the burden of asthma is more significant in the elderly than in their younger counterparts, particularly with regard to mortality, hospitalization, medical costs or health-related quality of life. Nevertheless, asthma in the elderly is still been underdiagnosed and undertreated. Therefore, it is an imperative task to recognize our current challenges and to set future directions. This project aims to review the current literature and identify unmet needs in the fields of research and practice for asthma in the elderly. This will enable us to find new research directions, propose new therapeutic strategies, and ultimately improve outcomes for elderly people with asthma. There are data to suggest that asthma in older adults is phenotypically different from young patients, with potential impact on the diagnosis, assessment and management in this population. The diagnosis of AIE in older populations relies on the same clinical findings and diagnostic tests used in younger populations, but the interpretation of the clinical data is more difficult. The challenge today is to encourage new research in AIE but to use the existing knowledge we have to make the diagnosis of AIE, educate the patient, develop a therapeutic approach to control the disease, and ultimately provide a better quality of life to our elderly patients.

Predictors of seasonal influenza vaccination in chronic asthma

BACKGROUND

Guidelines advise annual influenza vaccination in chronic asthma. The aim of this study was to determine uptake of the influenza vaccine in a group of patients (n = 146) with moderate to severe chronic asthma and establish the main predictors of vaccination.

METHOD

Patients attending a hospital asthma clinic were asked to complete a questionnaire in February 2012 (n = 146). These same patients were contacted a year later via telephone (n = 109 responded), and they were asked to complete the same questionnaire.

RESULTS

Vaccination rate was 50.3% in winter 2011/12, and 57.8% in 2012/13. Using binary logistic regression, the predictors for vaccination in 2012 were patient advice (Odds ratio [OR] 15.37 p = 0.001), female gender (OR 2.75, p = 0.028), past side effects (OR 0.21, p = 0.001) and comorbidity (OR 0.39, p = 0.013). Stepwise regression resulted in age as predictor (T value = 3.99, p = 0.001). On analyzing the responses from the second questionnaire at one year after attendance to asthma clinic, predictors changed to compliance to medication (OR 9.52, p= 0.001) and previous exacerbations (OR 4.19, p = 0.026). Out of the 56 patients vaccinated in 2011/12, 33 reported asthma exacerbations before 2012, and 29 reported asthma exacerbations after receiving the influenza vaccine. Out of the 46 unvaccinated patients in 2012, 27 had asthma exacerbations before 2012 and 19 patients had exacerbations in 2013. Patients vaccinated in 2011/12 needed 0.59 courses of steroid/patient/year, and 1.23 visits for nebulizer/patient/year while non-vaccinated patients needed 0.18 courses of steroids/patient/year (p = 0.048), and 0.65 visits for nebulized/patient/year (p = 0.012). Patients' subjective statements broadly confirmed the predictors. 16/69 (23.1%) received the vaccine in winter 2012/13 despite reporting previous side effects.

CONCLUSIONS

Advice to patient, female gender and patients' age predicted vaccination, while past side effects to the influenza vaccine, and presence of comorbidities predicted non vaccination. Symptomatic asthma patients are more likely to be vaccinated. One year after the first contact, treatment compliance and previous asthma exacerbations gained statistical significance as predictors of vaccination.

Influenza A(H1N1)pdm09 virus and asthma

Respiratory viral infection is a major cause of asthma exacerbations in both children and adults. Among the respiratory viruses, influenza virus is a particularly important pathogen due to its enormous morbidity and mortality in annual epidemics. The swine-origin influenza A virus, designated as A(H1N1)pdm09, emerged in the spring of 2009 and caused the first influenza pandemic in the 21st century. With the emergence of the novel A(H1N1)pdm09 virus, numerous epidemiologic studies detected asthma as a frequent comorbid condition in patients infected with this virus. Here we review recent reports regarding asthma in patients infected with influenza A(H1N1)pdm09 virus, and we discuss the utility of influenza vaccines and antivirals.

Guillain-Barré Syndrome, Influenza Vaccination, and Antecedent Respiratory and Gastrointestinal Infections: A Case-Centered Analysis in the Vaccine Safety Datalink, 2009-2011

BACKGROUND

Guillain-Barré Syndrome (GBS) can be triggered by gastrointestinal or respiratory infections, including influenza. During the 2009 influenza A (H1N1) pandemic in the United States, monovalent inactivated influenza vaccine (MIV) availability coincided with high rates of wildtype influenza infections. Several prior studies suggested an elevated GBS risk following MIV, but adjustment for antecedent infection was limited.

METHODS

We identified patients enrolled in health plans participating in the Vaccine Safety Datalink and diagnosed with GBS from July 2009 through June 2011. Medical records of GBS cases with 2009-10 MIV, 2010-11 trivalent inactivated influenza vaccine (TIV), and/or a medically-attended respiratory or gastrointestinal infection in the 1 through 141 days prior to GBS diagnosis were reviewed and classified according to Brighton Collaboration criteria for diagnostic certainty. Using a case-centered design, logistic regression models adjusted for patient-level time-varying sources of confounding, including seasonal vaccinations and infections in GBS cases and population-level controls.

RESULTS

Eighteen confirmed GBS cases received vaccination in the 6 weeks preceding onset, among 1.27 million 2009-10 MIV recipients and 2.80 million 2010-11 TIV recipients. Forty-four confirmed GBS cases had infection in the 6 weeks preceding onset, among 3.77 million patients diagnosed with medically-attended infection. The observed-versus-expected odds that 2009-10 MIV/2010-11 TIV was received in the 6 weeks preceding GBS onset was odds ratio = 1.54, 95% confidence interval (CI), 0.59-3.99; risk difference = 0.93 per million doses, 95% CI, -0.71-5.16. The association between GBS and medically-attended infection was: odds ratio = 7.73, 95% CI, 3.60-16.61; risk difference = 11.62 per million infected patients, 95% CI, 4.49-26.94. These findings were consistent in sensitivity analyses using alternative infection definitions and risk intervals for prior vaccination shorter than 6 weeks.

CONCLUSIONS

After adjusting for antecedent infections, we found no evidence for an elevated GBS risk following 2009-10 MIV/2010-11 TIV influenza vaccines. However, the association between GBS and antecedent infection was strongly elevated.

Influenza vaccination in children at high risk of respiratory disease

Chronic respiratory diseases (CRDs) are a heterogeneous group of diseases that can affect the pediatric population and health authorities throughout the world recommend influenza vaccination because of the significant risk of influenza-related complications. However, despite this recommendation, vaccine coverage is generally unsatisfactory. The aim of this review is to analyze the impact of influenza on children at high risk of respiratory disease, and the immunogenicity, safety and efficacy of influenza vaccination in such children. The results show that there is a significant risk of influenza-related complications in preterm neonates and infants, in whom influenza vaccines are immunogenic and safe (although their efficacy has not been specifically studied). There are conflicting data concerning the effect of influenza infection on asthma morbidity in children, and whether or not influenza vaccination helps to prevent asthma exacerbations. Recent data provide no evidence that influenza is more frequent in patients with cystic fibrosis than in healthy subjects, or that it is responsible for increased lower respiratory tract morbidity. The lack of any clear correlate of protection suggests that future studies should also consider the efficacy of the different influenza vaccines and not only evaluate them in terms of immunogenicity. Furthermore, there is a need for clinical studies to assess the effectiveness of the available vaccines in patients with other rare CRDs and other chronic underlying diseases with possibly severe respiratory involvement. It is also important to determine whether children with recurrent respiratory tract infections should be included in the list of those for whom influenza vaccination is recommended. In the meantime, given the increasing evidence of the burden of influenza on the population as a whole and the benefits associated with vaccination, annual influenza vaccinations should be recommended for all children at high risk of respiratory disease and the members of their households.

Correlation of care process measures with childhood asthma exacerbations

OBJECTIVE

We sought to define processes of pediatric asthma care identifiable through administrative data that correlate with asthma exacerbations for use in quality improvement.

METHODS

Commercially insured children aged 5 to 17 years from the Pediatric Physicians' Organization at Children's, an independent practice association affiliated with Boston Children's Hospital, with persistent asthma in 2008, 2009, or 2010 were identified. The correlations of various process measures with asthma exacerbations, defined as hospitalizations or emergency department visits for asthma or outpatient visits for asthma with an oral steroid prescription, were analyzed by using logistic regression.

RESULTS

Significant correlations were found between filling 0 vs ≥ 1 controller medications in all years (relative risk [RR] 3.35, 2.11, and 2.71 in 2008, 2009, and 2010, respectively) although only 4% of subjects overall filled no controller medications. The asthma medication ratio (controller prescriptions divided by total asthma prescriptions) was also associated with exacerbations, with the lowest 2 quartiles having a lower risk compared with the highest in all years (RR 2.27, 2.45, and 2.39 for the lowest; RR 2.10, 2.02, and 2.65 for the second quartile in 2008, 2009, and 2010, respectively).

CONCLUSIONS

Filling 0 vs ≥ 1 controllers and the asthma medication ratio correlated with asthma exacerbations. Although both might serve as quality improvement metrics for pediatric asthma, we favor the asthma medication ratio because it applies to a broader range of children with asthma and better reflects the recommended clinical approach for children with persistent asthma.

Efficacy and safety of influenza vaccination in children with asthma

The mean global prevalence of asthma among children is approximately 12%, making it the most common chronic disease in children. Influenza infection has been associated with complications such as exacerbations of wheezing and asthma, increased airway hyper-reactivity and hospitalization. Although influenza vaccination is recommended for asthmatic patients by all health authorities, vaccination coverage remains significantly lower than expected and is lowest of all in children. Compliance is affected by the uncertainty of parents and physicians concerning the clinical risk of influenza in asthmatic subjects, the benefits of influenza vaccination in preventing asthma exacerbations and the safety of immunization. The aim of this review is to analyze the rationale for using influenza vaccine, discuss the relationship between influenza and the severity of asthmatic episodes and document the efficacy and safety of influenza vaccination in the pediatric asthmatic population.

Vaccines for preventing influenza in healthy children

BACKGROUND

The consequences of influenza in children and adults are mainly absenteeism from school and work. However, the risk of complications is greatest in children and people over 65 years of age.

OBJECTIVES

To appraise all comparative studies evaluating the effects of influenza vaccines in healthy children, assess vaccine efficacy (prevention of confirmed influenza) and effectiveness (prevention of influenza-like illness (ILI)) and document adverse events associated with influenza vaccines.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 3) which includes the Acute Respiratory Infections Group's Specialised Register, OLD MEDLINE (1950 to 1965), MEDLINE (1966 to November 2011), EMBASE (1974 to November 2011), Biological Abstracts (1969 to September 2007), and Science Citation Index (1974 to September 2007).

SELECTION CRITERIA

Randomised controlled trials (RCTs), cohort and case-control studies of any influenza vaccine in healthy children under 16 years of age.

DATA COLLECTION AND ANALYSIS

Four review authors independently assessed trial quality and extracted data.

MAIN RESULTS

We included 75 studies with about 300,000 observations. We included 17 RCTs, 19 cohort studies and 11 case-control studies in the analysis of vaccine efficacy and effectiveness. Evidence from RCTs shows that six children under the age of six need to be vaccinated with live attenuated vaccine to prevent one case of influenza (infection and symptoms). We could find no usable data for those aged two years or younger.Inactivated vaccines in children aged two years or younger are not significantly more efficacious than placebo. Twenty-eight children over the age of six need to be vaccinated to prevent one case of influenza (infection and symptoms). Eight need to be vaccinated to prevent one case of influenza-like-illness (ILI). We could find no evidence of effect on secondary cases, lower respiratory tract disease, drug prescriptions, otitis media and its consequences and socioeconomic impact. We found weak single-study evidence of effect on school absenteeism by children and caring parents from work. Variability in study design and presentation of data was such that a meta-analysis of safety outcome data was not feasible. Extensive evidence of reporting bias of safety outcomes from trials of live attenuated influenza vaccines (LAIVs) impeded meaningful analysis. One specific brand of monovalent pandemic vaccine is associated with cataplexy and narcolepsy in children and there is sparse evidence of serious harms (such as febrile convulsions) in specific situations.

AUTHORS' CONCLUSIONS

Influenza vaccines are efficacious in preventing cases of influenza in children older than two years of age, but little evidence is available for children younger than two years of age. There was a difference between vaccine efficacy and effectiveness, partly due to differing datasets, settings and viral circulation patterns. No safety comparisons could be carried out, emphasising the need for standardisation of methods and presentation of vaccine safety data in future studies. In specific cases, influenza vaccines were associated with serious harms such as narcolepsy and febrile convulsions. It was surprising to find only one study of inactivated vaccine in children under two years, given current recommendations to vaccinate healthy children from six months of age in the USA, Canada, parts of Europe and Australia. If immunisation in children is to be recommended as a public health policy, large-scale studies assessing important outcomes, and directly comparing vaccine types are urgently required. The degree of scrutiny needed to identify all global cases of potential harms is beyond the resources of this review. This review includes trials funded by industry. An earlier systematic review of 274 influenza vaccine studies published up to 2007 found industry-funded studies were published in more prestigious journals and cited more than other studies independently from methodological quality and size. Studies funded from public sources were significantly less likely to report conclusions favourable to the vaccines. The review showed that reliable evidence on influenza vaccines is thin but there is evidence of widespread manipulation of conclusions and spurious notoriety of the studies. The content and conclusions of this review should be interpreted in the light of this finding.

Trivalent inactivated influenza vaccine is not associated with sickle cell crises in children

BACKGROUND AND OBJECTIVES

Children with sickle cell disease are considered at high risk for complications from influenza infection and are recommended to receive annual influenza vaccination. However, data on the safety of influenza vaccination in children with sickle cell anemia are sparse.

METHODS

Using a retrospective cohort of children aged 6 months to 17 years in 8 managed care organizations that comprise the Vaccine Safety Datalink and who had a diagnosis of sickle cell anemia from 1999 to 2006, we conducted matched case-control and self-controlled case series studies to examine the association of trivalent inactivated influenza vaccination with hospitalization for sickle cell crisis in the 2 weeks after vaccination.

RESULTS

From an original pool of 1085 pediatric subjects with a diagnosis of sickle cell anemia, we identified 179 children with at least 1 sickle cell crisis during any influenza season (October 1-March 31). In the matched case-control study (matching on age category, gender, Vaccine Safety Datalink site, and season), the odds ratio of hospitalization for a crisis in vaccinated compared with unvaccinated children was not significant: 1.3 (95% confidence interval 0.8-2.2). In the self-controlled case series study of hospitalized cases, the incident rate ratio for hospitalization with sickle cell crisis in the 2 weeks after trivalent inactivated influenza vaccination was also not significant: 1.2 (95% confidence interval 0.75-1.95).

CONCLUSION

This large cohort study did not find an association of influenza vaccination and hospitalization for sickle cell crises in children with sickle cell anemia.

Asthma exacerbations: origin, effect, and prevention

Asthma is the most common chronic respiratory disease, affecting up to 10% of adults and 30% of children in the Western world. Despite advances in asthma management, acute exacerbations continue to occur and impose considerable morbidity on patients and constitute a major burden on health care resources. Respiratory tract viruses have emerged as the most frequent triggers for exacerbations in both children and adults; however, the mechanisms underlying these remain poorly understood. More recently, it has become increasingly clear that interactions might exist between viruses and other triggers, increasing the likelihood of an exacerbation. In this article we begin with an overview of the health, economic, and social burden that exacerbations of asthma carry with them. This is followed by a review of the pathogenesis of asthma exacerbations, highlighting the various triggers responsible and multiple interactions that exist between them. The final section first addresses what preventative measures are currently available for asthma exacerbations and subsequently examines which of the new treatments in development might lessen the burden of exacerbations in the future.

Use of the self-controlled case-series method in vaccine safety studies: review and recommendations for best practice

The self-controlled case-series method was originally developed to investigate potential associations between vaccines and adverse events, and is now commonly used for this purpose. This study reviews applications of the method to vaccine safety investigations in the period 1995–2010. In total, 40 studies were reviewed. The application of the self-controlled case-series method in these studies is critically examined, with particular reference to the definition of observation and risk periods, control of confounders, assumptions and potential biases, methodological and presentation issues, power and sample size, and software. Comparisons with other study designs undertaken in the papers reviewed are also highlighted. Some recommendations are presented, with the emphasis on promoting good practice.

Viruses and asthma

Background

Viral respiratory infection has long been known to influence the occurrence of asthma exacerbations. Over the last 20 years much effort has been put into clarifying the role that viral respiratory infections play in the eventual development of asthma.

Scope of review

In this review we give a general background of the role of viruses in the processes of asthma exacerbation and asthma induction. We review recent additions to the literature in the last 3 years with particular focus on clinical and epidemiologic investigations of influenza, rhinovirus, bocavirus, respiratory syncytial virus, and metapneumovirus.

Major conclusions

The development of asthma emerges from a complex interaction of genetic predisposition and environmental factors with viral infection likely playing a significant role in the effect of environment on asthma inception. This article is part of a Special Issue entitled: Biochemistry of Asthma.

General significance

Further understanding of the role that viruses play in asthma exacerbation and inception will contribute to decreased asthma morbidity in the future. This article is part of a Special Issue entitled: Biochemistry of Asthma.

Vaccination of adults with asthma and COPD

Vaccines play a major role in preventing potentially life-threatening diseases. More attention is now focused on the adult population, particularly as they age, as a reservoir for vaccine-preventable diseases. Adults with comorbid conditions such as asthma and chronic obstructive pulmonary disease (COPD) are considered to be at higher risk for invasive diseases, many of which are preventable through routine vaccination. This article reviews the pertinent literature for the use of vaccines in the management of adult patients with asthma and COPD.

British Society for Allergy and Clinical Immunology guidelines for the management of egg allergy

This guideline advises on the management of patients with egg allergy. Most commonly, egg allergy presents in infancy, with a prevalence of approximately 2% in children and 0.1% in adults. A clear clinical history and the detection of egg white-specific IgE (by skin prick test or serum assay) will confirm the diagnosis in most cases. Egg avoidance advice is the cornerstone of management. Egg allergy often resolves and re-introduction can be achieved at home if reactions have been mild and there is no asthma. Patients with a history of severe reactions or asthma should have reintroduction guided by a specialist. All children with egg allergy should receive measles, mumps and rubella (MMR) vaccination. Influenza and yellow fever vaccines should only be considered in egg-allergic patients under the guidance of an allergy specialist. This guideline was prepared by the Standards of Care Committee (SOCC) of the British Society for Allergy and Clinical Immunology (BSACI) and is intended for allergists and others with a special interest in allergy. The recommendations are evidence-based but where evidence was lacking consensus was reached by the panel of specialists on the committee. The document encompasses epidemiology, risk factors, diagnosis, treatment, prognosis and co-morbid associations.

The economic implications of influenza vaccination for adults with asthma

BACKGROUND

Influenza vaccination is recommended for adults with asthma.

PURPOSE

This study estimates the effect of influenza vaccination on utilization of medical services and expenditures for acute and chronic respiratory conditions (ACRC) among adults with asthma.

METHODS

The sample was adults aged ≥18 years self-reporting asthma in the 2003 through 2006 Medical Expenditure Panel Survey (MEPS), covering four complete influenza seasons. The dependent variables were indicators for any ACRC claims within service category and ACRC expenditures. The main independent variable was an indicator of influenza vaccination. To control for selection bias in the observational data, a nonlinear instrumental variables approach was used. The instruments were indicators for influenza in the first year of MEPS and vaccination in the year prior to MEPS. Data were analyzed in 2009.

RESULTS

Adults with asthma vaccinated for influenza were 4.4 percentage points less likely to have an inpatient stay due to ACRC (95% CI = -10.8, -1.0). Influenza vaccination was associated with a $492 decrease (95% CI = -$1591, -$56) in annual ACRC nonprescription expenditures, a $224 increase (95% CI = $70, $360) in annual ACRC prescription expenditures, and a nonsignificant $216 decrease (95% CI = -$854, $248) in overall annual ACRC expenditures.

CONCLUSIONS

Although there was no evidence that vaccination reduced overall ACRC expenditures, the study suggests that efforts to increase the percentage of adults with asthma who are vaccinated may bring substantial benefits in terms of reducing the prevalence and costs of hospitalization although raising prescription medication costs, possibly through improvement in compliance.

Underestimation of influenza viral infection in childhood asthma exacerbations

Bocavirus was found in 11.6% of hospitalized children and 13% of ambulatory patients with exacerbations of asthma, and respiratory syncytial virus was found in 13.5% and 17.7%, respectively. In addition, influenza A virus was detected in 2.6% of hospitalized children and 14.1% (P<.001) of ambulatory-treated patients. Thus, the influenza burden in asthma may be underestimated.

Asthma prevalence and exacerbations in children: is there an association with childhood vaccination?

Infections and vaccinations may have a potential role in the normal maturation of the immune system, in the development and balance of regulatory pathways, and in the development and exacerbations of asthma. Asthma exacerbations often result from respiratory viral infections, and, while vaccination towards common viral infections may reduce the occurrence of such exacerbations, there has been concern that vaccinations can increase the risk of asthma. Current studies show that childhood vaccines, including inactivated influenza vaccine, are generally safe. However, there is some concern regarding possible exacerbations in infants or children with frequent wheezing or persistent asthma who are given live-attenuated influenza vaccination. Although severe allergic adverse events attributable to vaccination are extremely rare, all serious allergic reactions should be further assessed to detect the likely causative vaccine component, such as egg protein or gelatin. The risks of not vaccinating children far outweigh the risks of allergy and asthma exacerbations. Therefore, childhood vaccination should remain an essential part of child health programs and should not be withheld, even from children with asthma or those predisposed to allergy.

Safety of influenza vaccine administration in egg-allergic patients

OBJECTIVE

Current guidelines recommend that egg-allergic patients receive an influenza vaccine skin test before the influenza vaccine. This study evaluated the safety of bypassing the skin test and administering graded doses of influenza vaccine to egg-allergic children.

METHODS

We conducted a retrospective chart-review study of egg-allergic patients aged 6 months to 18 years who received the vaccine skin test and/or a 2-dose graded influenza vaccine. Between influenza seasons 2002-2003 and 2006-2007, egg-allergic patients underwent a vaccine skin test before influenza vaccine administration. Starting in 2006-2007, the skin test was removed from our protocol and egg-allergic patients received the influenza vaccine in 2 graded doses. All vaccinated patients were observed for adverse reactions.

RESULTS

Two hundred sixty-one egg-allergic patients were evaluated for influenza vaccine administration, and 171 went on to receive the vaccine. Of the 56 patients who received the skin test before the influenza vaccine, 95% (exact 95% confidence interval [CI]: 85.1-98.9) tolerated the vaccine without a serious adverse reaction. This rate was unchanged after the vaccine skin test was removed from the protocol. Of the 115 patients who received the vaccine without a preceding skin test, 97% (exact 95% CI: 91.3-99.0) tolerated the vaccine without serious adverse reaction. The tolerance rate ratio was 1.01 (95% CI: 0.97-1.06).

CONCLUSION

The results of our study suggest that egg-allergic patients without anaphylaxis to egg may safely receive the influenza vaccine in a 2-dose, graded fashion without a vaccine skin test.

Influenza vaccines: from surveillance through production to protection

Influenza is an important contributor to population and individual morbidity and mortality. The current influenza pandemic with novel H1N1 has highlighted the need for health care professionals to better understand the processes involved in creating influenza vaccines, both for pandemic as well as for seasonal influenza. This review presents an overview of influenza-related topics to help meet this need and includes a discussion of the burden of disease, virology, epidemiology, viral surveillance, and vaccine strain selection. We then present an overview of influenza vaccine-related topics, including vaccine production, vaccine efficacy and effectiveness, influenza vaccine misperceptions, and populations that are recommended to receive vaccination. English-language articles in PubMed published between January 1, 1970, and October 7, 2009, were searched using key words human influenza, influenza vaccines, influenza A, and influenza B.

Influenza-associated cystic fibrosis pulmonary exacerbations

BACKGROUND

Although cystic fibrosis (CF) is the most common inherited respiratory disease, the burden of influenza among individuals with CF is not well characterized.

METHODS

We used the CF Foundation Patient Registry to determine the relationship between pulmonary exacerbation incidence rate and influenza virus season from July 2003 through June 2007. The outcome of interest, pulmonary exacerbation, was defined as treatment of a respiratory illness with IV antibiotics. Each influenza season was defined as all months during which >/= 15% of laboratory tests for influenza virus were positive in the US influenza virologic surveillance system. We calculated incidence rates of pulmonary exacerbation during the influenza and summertime seasons as well as relative rates with 95% CIs. A multivariate regression model adjusted for demographic and clinical predictors.

RESULTS

In 2003, the patient cohort size was 21,506 patients, and 7,727 patients experienced at least one pulmonary exacerbation. The overall pulmonary exacerbation incidence rate in the influenza season was 595.0 per 10,000 person-months compared with a summertime baseline of 549.6 per 10,000 person-months. The incidence rate ratio was 1.08 (95% CI: 1.06, 1.10). Multivariate analysis did not change our estimate of risk (adjusted odds ratio: 1.07; 95% CI: 1.05, 1.10). An estimated annual excess of 147.6 per 10,000 person-months or an excess 2.1% of total exacerbations occur during the influenza season.

CONCLUSION

Our data demonstrate a substantial contribution of the influenza season to CF morbidity. Further studies to determine any causal link between influenza infection and CF pulmonary exacerbations are necessary.

Virus vaccines and children with asthma

PURPOSE OF REVIEW

To describe what is currently known about the role of virus vaccines in the pathogenesis of asthma and atopy and summarize their role in the prevention of morbidity due to childhood asthma.

RECENT FINDINGS

The development of virus vaccines and their incorporation into infant and childhood immunization programmes over the last few decades of the twentieth century have been accompanied by a striking concomitant rise in the incidence of asthma and atopy. However, a causal relationship is not supported by the majority of observational studies. The role of childhood immunization against respiratory viruses in the reduction of morbidity from asthma is another important public health issue. Recent findings suggest that influenza is not strongly associated with exacerbations of asthma in children, despite recommendations that this group should be immunized against it.

SUMMARY

Current evidence suggests that virus vaccination is well tolerated and does not lead to an increased incidence of asthma or atopy in children receiving vaccines. Debate continues regarding the place of respiratory virus vaccination in the therapeutic armamentarium for children with asthma. In the case of influenza, there appears to be an absence of harm, but benefit seems to be limited to younger children.

Does influenza vaccination improve pediatric asthma outcomes?

OBJECTIVE

Controversy exists regarding the effectiveness of influenza vaccination in preventing influenza-related asthma exacerbations in the pediatric population. While yearly influenza immunization is widely recommended for children with asthma, there is currently little evidence to support this practice. Several studies have demonstrated no measurable benefit in asthma outcomes. This study sought to determine whether influenza vaccination status is associated with indicators of asthma morbidity within the military pediatric population.

METHODS

A survey was conducted of patients 3 to 18 years of age with a diagnosis of asthma enrolled in the pediatric clinics of Brooke Army Medical Center, Fort Sam Houston, Texas, and Wilford Hall Medical Center, Lackland Air Force Base, Texas. Management practices and outcomes for 80 children were evaluated. Data were analyzed using the statistical package SPSS version 12 (SPSS Inc., Chicago). Univariate analyses were performed to identify associations between influenza vaccination, selected demographic variables and asthma exacerbation defined by oral steroid prescription, hospital visits, and unscheduled clinic or emergency department visits for asthma symptoms. Logistic regression analyses were conducted to detect possible confounding variables.

RESULTS

In the univariate analyses, current influenza vaccination status was associated with a significant reduction of oral steroid use in the 12 months before the survey. This relationship was appreciated to a lesser extent with emergency department or unscheduled clinic visits in the last 12 months. No significant differences were found regarding the distribution of influenza vaccination status across selected demographic variables. In the multivariate analyses, current influenza vaccination status was independently associated with significantly decreased odds of using oral steroids in the previous 12 months. There was no evidence of confounding or effect modification.

CONCLUSIONS

This study suggests influenza vaccination is associated with fewer asthma exacerbations. After controlling for several potential confounding variables, administration of influenza vaccine was associated with a protective effect against indicators of asthma exacerbations. Our results indicate that children with asthma in the military beneficiary population may benefit from annual influenza vaccination.

The Role of Influenza Vaccination in Asthmatic Children

Asthma is the most occurring chronic disease in children. Asthma related genes and environmental factors play a role in the etiology. Nowadays, asthma is regarded as a chronic inflammatory disease of the airways instead of solely a reversible airway obstruction. Asthma is often diagnosed on specific symptoms such as chest tightness, wheezing, dyspnea, and coughing. It is likely that, rather than a single disease entity, asthma consists of related, partially overlapping syndromes. The first symptoms often are experienced before the age of 5. Children with the highest risk have a family history of atopy and/or asthma. Viral infections with symptoms of wheezing acquired in the first year of life may be associated with the risk of developing asthma later on [1]. However, making the diagnosis with a reasonable certainty that is supported by spirometry is only possible from the age of 6 onward. More than 50% of children with a period of wheezing earlier on in life are not diagnosed as having asthma at the age of 6 [2].

The use of rescue and anti-inflammatory medication has largely altered the prospects of asthma patients and has improved their quality of life. Thus, nowadays, most asthma patients lead a normal life without restrictions. Disease control achieved by the asthmatics is an important predictor of the likelihood of complications of the disease [3]. However, asthma exacerbations neither respond to inhaled steroids nor can they substantially be prevented in this way [4, 5]. Only the use of oral corticos-teroids seems to be unmistakably effective in case of exacerbations [6, 7].

Improving influenza vaccination rates for pediatric asthmatics by use of an asthma educational tool and a patient electronic care system

A prescription-sized asthma educational tool (AET) was used to identify, assess, and educate pediatric asthma patients during a 2-year period. A Patient Electronic Care System (PECS) was used to register these patients over 2 influenza vaccination seasons to determine whether influenza vaccination rates could be improved among these pediatric asthmatics by use of the asthma educational tool. During this study, influenza vaccination rates among all asthmatics increased over 450% from 2003 to 2004 influenza season compared with 2006 to 2007 influenza season (13.1%-59.4%). The mild persistent to severe persistent asthmatics subgroup in this pool of patients also improved their influenza vaccination rates over 250% from the 2003 to 2004 influenza season to the 2006 to 2007 influenza season (36.6%-91.7%). All the results were statistically significant to 95% confidence levels.

Vaccines for preventing influenza in healthy children

BACKGROUND

The consequences of influenza in children and adults are mainly absenteeism from school and work. However, the risk of complications is greatest in children and people over 65 years old.

OBJECTIVES

To appraise all comparative studies evaluating the effects of influenza vaccines in healthy children; assess vaccine efficacy (prevention of confirmed influenza) and effectiveness (prevention of influenza-like illness) and document adverse events associated with influenza vaccines.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2007, issue 3); OLD MEDLINE (1950 to 1965); MEDLINE (1966 to September 2007); EMBASE (1974 to September 2007); Biological Abstracts (1969 to September 2007); and Science Citation Index (1974 to September 2007).

SELECTION CRITERIA

Randomised controlled trials (RCTs), cohort and case-control studies of any influenza vaccine in healthy children under 16 years of age.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data.

MAIN RESULTS

Fifty-one studies with 294,159 observations were included. Sixteen RCTs and 18 cohort studies were included in the analysis of vaccine efficacy and effectiveness. From RCTs, live vaccines showed an efficacy of 82% (95% confidence interval (CI) 71% to 89%) and an effectiveness of 33% (95% CI 28% to 38%) in children older than two compared with placebo or no intervention. Inactivated vaccines had a lower efficacy of 59% (95% CI 41% to 71%) than live vaccines but similar effectiveness: 36% (95% CI 24% to 46%). In children under two, the efficacy of inactivated vaccine was similar to placebo. Variability in study design and presentation of data was such that a meta-analysis of safety outcome data was not feasible. Extensive evidence of reporting bias of safety outcomes from trials of live attenuated vaccines impeded meaningful analysis.

AUTHORS' CONCLUSIONS

Influenza vaccines are efficacious in children older than two but little evidence is available for children under two. There was a marked difference between vaccine efficacy and effectiveness. No safety comparisons could be carried out, emphasizing the need for standardisation of methods and presentation of vaccine safety data in future studies. It was surprising to find only one study of inactivated vaccine in children under two years, given current recommendations to vaccinate healthy children from six months old in the USA and Canada. If immunisation in children is to be recommended as a public health policy, large-scale studies assessing important outcomes and directly comparing vaccine types are urgently required.