Hospitalization of children with influenza A(H1N1) virus in Israel during the 2009 outbreak in Israel: a multicenter survey

Safety of Pelargonium extract EPs 7630 in young children with acute bronchitis

BACKGROUND

The efficacy and tolerability of Pelargonium sidoides DC. root extract EPs 7630 in children with acute bronchitis (AB) have been widely demonstrated. We investigated the safety and tolerability of a syrup formulation and an oral solution in pre-school children.

METHODS

In an open-label, randomized clinical trial (EudraCT number 2011-002652-14), children aged 1-5 years suffering from AB received EPs 7630 syrup or solution for 7 days. Safety was assessed by frequency, severity, and nature of adverse events (AE), vital signs, and laboratory values. Outcome measures for evaluating the health status were the intensity of coughing, pulmonary rales, and dyspnea, measured by the short version of the Bronchitis Severity Scale (BSS-ped), further symptoms of the respiratory infection, general health status according to the Integrative Medicine Outcomes Scale (IMOS), and satisfaction with treatment according to the Integrative Medicine Patient Satisfaction Scale (IMPSS).

RESULTS

591 children were randomized and treated with syrup (n = 403) or solution (n = 188) for 7 days. In both treatment groups, the number of adverse events was similarly low and revealed no safety concerns. The most frequently observed events were infections (syrup: 7.2%; solution: 7.4%) or gastrointestinal disorders (syrup: 2.7%; solution: 3.2%). After one week's treatment, more than 90% of the children experienced an improvement or remission of the symptoms of the BSS-ped. Further respiratory symptoms decreased similarly in both groups. At Day 7, more than 80% of the whole study population had completely recovered or showed a major improvement as assessed by the investigator and the proxy, respectively. Parents were "very satisfied" or "satisfied" with the treatment in 86.1% of patients in the combined syrup and solution group.

CONCLUSION

Both pharmaceutical forms, EPs 7630 syrup and oral solution, were shown to be equally safe and well tolerated in pre-school children suffering from AB. Improvement of health status and of complaints were similar in both groups.

Characteristics of hospitalised patients with influenza in 2015-2016 in northern Israel: three circulating strains and continued fear of 2009 A/H1N1

This study aimed to characterise children and adults diagnosed with influenza who were admitted to three medical centres in northern Israel in the winter of 2015-2016, a unique season due to infection with three types of influenza strains: A/H1N1, A/non-H1N1 and B. Data were collected retrospectively from medical records. Influenza A/H1N1 infected mainly adults (61% vs. 16% in children, P < 0.001) while influenza B was the common type in children (54% vs. 28% in adults, P < 0.001). Adults (36% vs. 5% in children, P < 0.001) and patients infected with A/H1N1 had higher rates of pneumonia (34% vs. 16% and 14% in influenza B and A/non-H1N1, respectively, P = 0.002). Treatment with oseltamivir was prescribed to 90% of patients; adults had higher rates of treatment (96% vs. 84% in children, P = 0.002) as well as patients infected with A/H1N1 (96% vs. 86% in influenza B and A/non-H1N1, respectively, P = 0.04). Oseltamivir was given after a mean of 3.6 days of symptoms. Preferential infection of adults by A/H1N1 was evident in Israel in 2015-2016; pneumonia rates were higher in adults and in A/H1N1-infected patients. Oseltamivir was prescribed to most patients but especially to those infected with A/H1N1, and was given relatively late in the course of the disease.

The role of pneumonia and secondary bacterial infection in fatal and serious outcomes of pandemic influenza a(H1N1)pdm09

BACKGROUND

The aim of this study was to estimate the prevalence of pneumonia and secondary bacterial infections during the pandemic of influenza A(H1N1)pdm09.

METHODS

A systematic review was conducted to identify relevant literature in which clinical outcomes of pandemic influenza A(H1N1)pdm09 infection were described. Published studies (between 01/01/2009 and 05/07/2012) describing cases of fatal or hospitalised A(H1N1)pdm09 and including data on bacterial testing or co-infection.

RESULTS

Seventy five studies met the inclusion criteria. Fatal cases with autopsy specimen testing were reported in 11 studies, in which any co-infection was identified in 23% of cases (Streptococcus pneumoniae 29%). Eleven studies reported bacterial co-infection among hospitalised cases of A(H1N1)2009pdm with confirmed pneumonia, with a mean of 19% positive for bacteria (Streptococcus pneumoniae 54%). Of 16 studies of intensive care unit (ICU) patients, bacterial co-infection identified in a mean of 19% of cases (Streptococcus pneumoniae 26%). The mean prevalence of bacterial co-infection was 12% in studies of hospitalised patients not requiring ICU (Streptococcus pneumoniae 33%) and 16% in studies of paediatric patients hospitalised in general or pediatric intensive care unit (PICU) wards (Streptococcus pneumoniae 16%).

CONCLUSION

We found that few studies of the 2009 influenza pandemic reported on bacterial complications and testing. Of studies which did report on this, secondary bacterial infection was identified in almost one in four patients, with Streptococcus pneumoniae the most common bacteria identified. Bacterial complications were associated with serious outcomes such as death and admission to intensive care. Prevention and treatment of bacterial secondary infection should be an integral part of pandemic planning, and improved uptake of routine pneumococcal vaccination in adults with an indication may reduce the impact of a pandemic.

Nationwide Study on the Course of Influenza A (H1N1) Infections in Hospitalized Children in the Netherlands During the Pandemic 2009-2010

BACKGROUND

The influenza H1N1 pandemic of 2009-2010, provided a unique opportunity to assess the course of disease, as well as the analysis of risk factors for severe disease in hospitalized children (< 18 years).

METHODS

Retrospective national chart study on hospitalized children with H1N1 infection during the 2009-2010 pH1N1 outbreak.

RESULTS

Nine hundred forty patients (56% boys), median age 3.0 years, were enrolled; the majority were previously healthy. Treatment consisted of supplemental oxygen (24%), mechanical ventilation (5%) and antiviral therapy (63%). Fifteen patients died (1.6%), 5 of whom were previously healthy. Multivariable analyses confirmed pre-existent heart and lung disease as risk factors for intensive care unit admission. Risk factors for mortality included children with a neurologic or oncologic disease and psychomotor retardation.

CONCLUSIONS

This nationwide overview of hospitalized children confirms known risk groups for severe influenza infections. However, most of the acute and severe presentations of influenza occurred in previously healthy children.

Possible explanations for why some countries were harder hit by the pandemic influenza virus in 2009 - a global mortality impact modeling study

BACKGROUND

A global pandemic mortality study found prominent regional mortality variations in 2009 for Influenza A(H1N1)pdm09. Our study attempts to identify factors that explain why the pandemic mortality burden was high in some countries and low in others.

METHODS

As a starting point, we identified possible risk factors worth investigating for Influenza A(H1N1)pdm09 mortality through a targeted literature search. We then used a modeling procedure (data simulations and regression models) to identify factors that could explain differences in respiratory mortality due to Influenza A(H1N1)pdm09. We ran sixteen models to produce robust results and draw conclusions. In order to assess the role of each factor in explaining differences in excess pandemic mortality, we calculated the reduction in between country variance, which can be viewed as an effect-size for each factor.

RESULTS

The literature search identified 124 publications and 48 possible risk factors, of which we were able to identify 27 factors with appropriate global datasets. The modelling procedure indicated that age structure (explaining 40% of the mean between country variance), latitude (8%), influenza A and B viruses circulating during the pandemic (3-8%), influenza A and B viruses circulating during the preceding influenza season (2-6%), air pollution (pm10; 4%) and the prevalence of other infections (HIV and TB) (4-6%) were factors that explained differences in mortality around the world. Healthcare expenditure, levels of obesity, the distribution of antivirals, and air travel did not explain global pandemic mortality differences.

CONCLUSIONS

Our study found that countries with a large proportion of young persons had higher pandemic mortality rates in 2009. The co-circulation of influenza viruses during the pandemic and the circulation of influenza viruses during the preceding season were also associated with pandemic mortality rates. We found that real time assessments of 2009 pandemic mortality risk factors (e.g. obesity) probably led to a number of false positive findings.

Incidence of laboratory-confirmed influenza disease among infants under 6 months of age: a systematic review

OBJECTIVES

The aim of this systematic review was to assess incidence rates of laboratory-confirmed influenza (LCI) outcomes among infants under 6 months of age.

DESIGN

Systematic literature search and review of indexed studies in PubMed, EMBASE, the Cochrane Library and CINAHL Plus from inception to 19 April 2017.

SETTING

Population-based estimates from community or hospital settings.

PARTICIPANTS

Infants under 6 months of age.

PRIMARY AND SECONDARY OUTCOME MEASURES

LCI illness in ambulatory care settings, LCI hospitalisation, LCI intensive care unit admission and LCI death. Only studies with population-based incidence data were included.

RESULTS

We identified 27 primary studies, 11 of which were from the USA, four were from other non-US high-income settings and the remaining were from lower-middle-income or upper-middle-income countries. Most studies (n=23) assessed incidence of LCI hospitalisation, but meta-analysis to pool study-specific rates was not possible due to high statistical and methodological heterogeneity. Among US studies, the reported incidence of LCI hospitalisation ranged from 9.3 to 91.2 per 10 000 infants under 6 months for seasonal influenza, while the only US-based estimate for pandemic H1N1 influenza was 20.2 per 10 000 infants. Reported rates for LCI hospitalisation for seasonal influenza from other countries ranged from 6.2 to 73.0 per 10 000 infants under 6 months, with the exception of one study with an estimated rate of 250 per 10 000 infants. No events were reported in five of the nine studies that evaluated LCI death among infants under 6 months.

CONCLUSION

Our review of published studies found limited data on LCI outcomes for infants under 6 months, particularly from non-US settings. Globally representative and reliable incidence data are necessary to fully evaluate influenza disease burden and the potential impact of maternal influenza immunisation programme on morbidity and mortality in young infants.

The PAndemic INfluenza Triage in the Emergency Department (PAINTED) pilot cohort study

BACKGROUND

Research needs to be undertaken rapidly in the event of an influenza pandemic to develop and evaluate triage methods for people presenting to the emergency department with suspected pandemic influenza.

OBJECTIVES

We aimed to pilot a research study to be undertaken in a pandemic to identify the most accurate triage method for patients presenting to the emergency department with suspected pandemic influenza. The objectives of the pilot study were to develop a standardised clinical assessment form and secure online database; test both using data from patients with seasonal influenza; seek clinician views on the usability of the form; and obtain all regulatory approvals required for the main study.

DESIGN

Study methods were piloted using an observational cohort study and clinician views were sought using qualitative, semistructured interviews.

SETTING

Six acute hospital emergency departments.

PARTICIPANTS

Patients attending the emergency department with suspected seasonal influenza during winter 2012-13 and clinicians working in the emergency departments.

MAIN OUTCOME MEASURES

Adverse events up to 30 days were identified, but analysis of the pilot data was limited to descriptive reporting of patient flow, data completeness and patient characteristics.

RESULTS

Some 165 patients were identified, of whom 10 withdrew their data, leaving 155 (94%) for analysis. Follow-up data were available for 129 of 155 (83%), with 50 of 129 (39%) being admitted to hospital. Three cases (2%) were recorded as having suffered an adverse outcome. There appeared to be variation between the hospitals, allowing for small numbers. Three of the hospitals identified 150 of 165 (91%) of the patients, and all 10 withdrawing patients were at the same hospital. The proportion with missing follow-up data varied from 8% to 31%, and the proportion admitted varied from 4% to 85% across the three hospitals with meaningful numbers of cases. All of the deaths were at one hospital. There was less variation between hospitals in rates of missing data, and for most key variables missing rates were between 5% and 30%. Higher missing rates were recorded for blood pressure (39%), inspired oxygen (43%), capillary refill (36%) and Glasgow Coma Scale score (43%). Chest radiography was performed in 51 of 118 cases, and electrocardiography in 40 of 111 cases with details recorded. Blood test results were available for 32 of 155 cases. The qualitative interviews revealed generally positive views towards the standardised assessment form. Concerns about lack of space for free text were raised but counterbalanced by appreciation that it fitted on to one A4 page. A number of amendments were suggested but only three of these were suggested by more than one participant, and no suggestions were made by more than two participants.

CONCLUSIONS

A standardised assessment form is acceptable to clinicians and could be used to collect research data in an influenza pandemic, but analysis may be limited by missing data.

FUTURE WORK

An observational cohort study to identify the most accurate triage method for predicting severe illness in emergency department attendees with suspected pandemic influenza is set up and ready to activate if, or when, a pandemic occurs.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN56149622.

FUNDING

This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 19, No. 3. See the NIHR Journals Library website for further project information.

The burden of seasonal and pandemic influenza in infants and children

The burden of influenza is unevenly distributed, with more severe outcomes in children aged <5 years than older children and adults. In spite of this, immunisation policies for young children are far from universal. This article provides an overview of the published evidence on the burden of influenza in children worldwide, with a particular interest in the impact of pandemic influenza in 2009-2010 (caused by the H1N1pdm09 virus). In an average season, up to 9.8 % of 0- to 14-year olds present with influenza, but incidence rates can be markedly higher in younger children. Children aged <5 years have greater rates of hospitalisation and complications than their older counterparts, particularly if the children have co-existing illnesses; historically, this age group have had higher mortality rates from the disease than other children, although during the 2009-2010 pandemic the median age of those who died of influenza was higher than in previous seasons. Admissions to hospital and emergency departments appear to have been more frequent in children with H1N1pdm09 infections than during previous seasonal epidemics, with pneumonia continuing to be a common complication in this setting. Outcomes in children hospitalised with severe disease also seem to have been worse for those infected with H1N1pdm09 viruses compared with seasonal viruses. Studies in children confirm that vaccination reduces the incidence of seasonal influenza and the associated burden, underlining the importance of targeting this group in national immunisation policies.

CONCLUSIONS

Children aged <5 years are especially vulnerable to influenza, particularly that caused by seasonal viruses, and vaccination in this group can be an effective strategy for reducing disease burden.

Influenza in hospitalized children in Ireland in the pandemic period and the 2010/2011 season: risk factors for paediatric intensive-care-unit admission

Influenza causes significant morbidity and mortality in children. This study's objectives were to describe influenza A(H1N1)pdm09 during the pandemic, to compare it with circulating influenza in 2010/2011, and to identify risk factors for severe influenza defined as requiring admission to a paediatric intensive care unit (PICU). Children hospitalized with influenza during the pandemic were older, and more likely to have received antiviral therapy than children hospitalized during the 2010/2011 season. In 2010/2011, only one child admitted to a PICU with underlying medical conditions had been vaccinated. The risk of severe illness in the pandemic was higher in females and those with underlying conditions. In 2010/2011, infection with influenza A(H1N1)pdm09 compared to other influenza viruses was a significant risk factor for severe disease. An incremental relationship was found between the number of underlying conditions and PICU admission. These findings highlight the importance of improving low vaccination uptake and increasing the use of antivirals in vulnerable children.

Populations at risk for severe or complicated influenza illness: systematic review and meta-analysis

OBJECTIVE

To evaluate risk factors for severe outcomes in patients with seasonal and pandemic influenza.

DESIGN

Systematic review.

STUDY SELECTION

Observational studies reporting on risk factor-outcome combinations of interest in participants with influenza. Outcomes included death, ventilator support, admission to hospital, admission to an intensive care unit, pneumonia, and composite outcomes.

DATA SOURCES

Medline, Embase, CINAHL, Global Health, and the Cochrane Central Register of Controlled Trials to March 2011.

RISK OF BIAS ASSESSMENT

Newcastle-Ottawa scale to assess the risk of bias. GRADE framework to evaluate the quality of evidence.

RESULTS

63 537 articles were identified of which 234 with a total of 610 782 participants met the inclusion criteria. The evidence supporting risk factors for severe outcomes of influenza ranged from being limited to absent. This was particularly relevant for the relative lack of data for non-2009 H1N1 pandemics and for seasonal influenza studies. Limitations in the published literature included lack of power and lack of adjustment for confounders was widespread: adjusted risk estimates were provided for only 5% of risk factor-outcome comparisons in 39 of 260 (15%) studies. The level of evidence was low for "any risk factor" (odds ratio for mortality 2.77, 95% confidence interval 1.90 to 4.05 for pandemic influenza and 2.04, 1.74 to 2.39 for seasonal influenza), obesity (2.74, 1.56 to 4.80 and 30.1, 1.74 to 2.39), cardiovascular diseases (2.92, 1.76 to 4.86 and 1.97, 1.06 to 3.67), and neuromuscular disease (2.68, 1.91 to 3.75 and 3.21, 1.84 to 5.58). The level of evidence was very low for all other risk factors. Some well accepted risk factors such as pregnancy and belonging to an ethnic minority group could not be identified as risk factors. In contrast, women who were less than four weeks post partum had a significantly increased risk of death from pandemic influenza (4.43, 1.24 to 15.81).

CONCLUSION

The level of evidence to support risk factors for influenza related complications is low and some well accepted risk factors, including pregnancy and ethnicity, could not be confirmed as risks. Rigorous and adequately powered studies are needed.

Predictors of severe H1N1 infection in children presenting within Pediatric Emergency Research Networks (PERN): retrospective case-control study

OBJECTIVE

To identify historical and clinical findings at emergency department presentation associated with severe H1N1 outcome in children presenting with influenza-like illness.

DESIGN

Multicentre retrospective case-control study.

SETTING

79 emergency departments of hospitals associated with the Pediatric Emergency Research Networks in 12 countries.

PARTICIPANTS

265 children (<16 years), presenting between 16 April and 31 December 2009, who fulfilled Centers for Disease Control and Prevention criteria for influenza-like illness and developed severe outcomes from laboratory confirmed H1N1 infection. For each case, two controls presenting with influenza-like illness but without severe outcomes were included: one random control and one age matched control.

MAIN OUTCOME MEASURES

Severe outcomes included death or admission to intensive care for assisted ventilation, inotropic support, or both. Multivariable conditional logistic regression was used to compare cases and controls, with effect sizes measured as adjusted odds ratios.

RESULTS

151 (57%) of the 265 cases were male, the median age was 6 (interquartile range 2.3-10.0) years, and 27 (10%) died. Six factors were associated with severe outcomes in children presenting with influenza-like illness: history of chronic lung disease (odds ratio 10.3, 95% confidence interval 1.5 to 69.8), history of cerebral palsy/developmental delay (10.2, 2.0 to 51.4), signs of chest retractions (9.6, 3.2 to 29.0), signs of dehydration (8.8, 1.6 to 49.3), requirement for oxygen (5.8, 2.0 to 16.2), and tachycardia relative to age).

CONCLUSION

These independent risk factors may alert clinicians to children at risk of severe outcomes when presenting with influenza-like illness during future pandemics.

Multi-centre observational study of transplacental transmission of influenza antibodies following vaccination with AS03(A)-adjuvanted H1N1 2009 vaccine

Introduction

Illness and death from influenza increase during pregnancy. In the United Kingdom pregnant women were targeted in a national programme for vaccination during the H1N1 2009–10 pandemic.

Methods

In this study, pregnant women were recruited in labour from November 9, 2009 to March 10, 2010. Pandemic vaccination status was determined. Venous cord blood collected at delivery was evaluated for transplacental transfer of antibodies by measurement of haemagglutination inhibition and microneutralization titres.

Results

Samples were collected from 77 vaccinated and 27 unvaccinated women. Seroprotection (HI titre ≥1∶40) was detected in 58 (75.3%, 95% CI 64.2–84.4) cord blood samples from vaccinated women and 5 (18.5%, 95% CI 6.3–38.1) from unvaccinated women (P<0.0001). There was evidence of transplacental seroprotection 8 days after maternal immunization (77.9%, 95 CI 66.2–87.1), maintained in most cases for at least 16 weeks.

Discussion

Immunization of pregnant women with AS03_A-adjuvanted vaccine is followed by transplacental transfer of passive immunity at titres consistent with clinical protection in three-quarters of new-born infants. The findings support national and international pandemic H1N1 2009 recommendations for immunization during pregnancy.

Risk factors for mechanical ventilation in U.S. children hospitalized with seasonal influenza and 2009 pandemic influenza A*

OBJECTIVE

We tested the hypothesis that the use of mechanical ventilator support in children hospitalized with influenza during the 2009 H1N1 influenza A (H1N1) pandemic was higher than would be expected in children hospitalized for seasonal influenza after adjusting for patient risk.

DESIGN

Retrospective cohort study.

SETTING

Forty-three U.S. pediatric hospitals.

PATIENTS

Children <18 yrs old with a discharge diagnosis of influenza admitted July 2006 through March 2009 (seasonal influenza) and June through December 2009 (2009 pandemic influenza A).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We included 10,173 children hospitalized with seasonal influenza and 9837 with presumed 2009 pandemic influenza A. The 2009 pandemic influenza A cohort was older (median 5.0 vs. 1.9 yrs), more likely to have asthma (30% vs. 18%), and less likely to receive mechanical ventilation (7.1% [n = 701] vs. 9.2% [n = 940]). Using logistic regression, we created a multivariable model of risk factors associated with endotracheal mechanical ventilator support in the seasonal influenza cohort and used this model to predict the number of expected mechanical ventilation cases in children with presumed 2009 pandemic influenza A. Adjusted for underlying health conditions, race, age, and a co-diagnosis of bacterial pneumonia, the observed/expected rate of mechanical ventilation in the presumed 2009 pandemic influenza A cohort was 0.74 (95% confidence interval 0.68-0.79). Early hospital treatment with influenza antiviral medications was associated with decreased initiation of mechanical ventilation on hospital day ≥ 3 in the seasonal influenza (odds ratio 0.66; 95% confidence interval 0.45-0.97) and 2009 pandemic influenza A (odds ratio 0.23; 95% confidence interval 0.16-0.34) periods; influenza antiviral use in the 2009 pandemic influenza A period was much higher (70% vs. 20%; p < .001).

CONCLUSIONS

Although the number of children with a hospital discharge diagnosis of influenza almost tripled during the 2009 pandemic influenza A period, the risk-adjusted proportion of children receiving mechanical ventilation was lower than we would have predicted in a seasonal influenza cohort. Early hospital use of influenza antiviral medications was associated with a decrease in late-onset mechanical ventilation.

Post-marketing assessment of neuropsychiatric adverse events in influenza patients treated with oseltamivir: an updated review

A 2008 review by our group concluded that the risk of neuropsychiatric adverse events (NPAEs) in influenza patients was not increased by oseltamivir exposure, and did not identify any mechanism by which oseltamivir or its metabolites could cause or worsen such events. The current article reviews new information on this topic. Between September 16, 2007 and May 15, 2010, 1,805 spontaneously-reported NPAEs were identified in 1,330 patients receiving oseltamivir: 767 (42.5%) from Japan, 296 (16.4%) from the USA, and 742 (41.1%) from other countries. NPAEs were more common in children: 1,072 (59.4%) events were in those aged ≤16 years. NPAEs often occurred within 48 h of treatment initiation (953 events; 52.8%). Nearly half of the events were serious in nature (838; 46.4%). The three largest categories of events were abnormal behavior (457 events, 25.3%), miscellaneous psychiatric events (370; 20.5%), and delusions/perceptual disturbances (316 events, 17.5%). A total of 1,545 events (85.6%) in eight different categories were considered to be delirium or delirium-like. Twenty-eight suicide-related events were reported. A US healthcare claims database analysis showed that the risk of NPAEs in 7,798 oseltamivir-treated patients was no higher than that in 10,411 patients not on antivirals, but a study on oseltamivir and abnormal behavior in Japan was less conclusive. NPAE frequency in oseltamivir-exposed Japanese and Taiwanese children with influenza was the same as in unexposed children. New analysis of the UK General Practice Research Database showed that the relative adjusted risk of NPAEs in influenza patients was 2.18-times higher than in the general population. Other epidemiology studies report frequent occurrence of encephalitis and similar disorders in influenza patients independently of oseltamivir exposure. The new data support the findings of the original assessment. Evidence suggests that influenza-related encephalopathies are caused by influenza-induced inflammatory responses, but more work is needed to confirm the underlying mechanisms.

Characteristics of hospitalized children with 2009 pandemic influenza A (H1N1): a multicenter study in Korea

The majority of Korean patients with pandemic influenza A (H1N1) during the 2009 epidemic were under 20 yr of age. The limited data on the clinical characteristics of these children led us to conduct a case note-based investigation of children admitted to 6 university hospitals with 2009 H1N1 influenza. A total of 804 children was enrolled. The median age was 5 yr; 63.8% were males; and 22.4% had at least one chronic underlying disease. Ninety-five of the patients (11.8%) were critically ill and they suffered more from shortness of breath, dyspnea and lymphopenia than the other patients. Among all the patients, 98.8% were treated with antivirals and 73% received treatment within 48 hr of illness onset. All the enrolled patients are alive and appear to have had good outcomes, probably due to the early intervention and antiviral treatment. This study deals with hospitalized children whose diagnoses of influenza A (H1N1) were confirmed, and therefore provides important new information about the clinical patterns of children with influenza A (H1N1) in Korea.

Clinical features of infants hospitalized for 2009 pandemic influenza A (H1N1) in Japan: analysis using a national hospital discharge database

BACKGROUND

Earlier studies reported that infants <12 months of age were at high risk of hospitalization for 2009 pandemic influenza A H1N1 virus (2009 H1N1) infection, but there was little information about the clinical courses in these patients.

METHODS

A retrospective study was performed using the nationwide inpatient Diagnosis Procedure Combination Database in Japan. We searched data on hospitalizations, between July and December 2009, of infants (<12 months) and children 12 to <24 months of age with influenza. We examined their demographic data and hospitalization details, including treatment, complications, and outcomes.

RESULTS

During the study period, 1023 infants were hospitalized for influenza; 98.1% of them were previously healthy. Complications attributed to influenza were found in 181 (17.7%) infants, including 3 critical illnesses and 1 death. Oseltamivir was prescribed to 535 (53.3%) infants. We found no evidence that oseltamivir was associated with either complications or length of hospital stay. During the same period, 579 children 1 year of age were admitted for 2009 H1N1, and 56.5% of them had influenza-related complications.

CONCLUSIONS

In Japan, infants with 2009 H1N1 were twice as likely to be hospitalized as children 1 year of age. However, the clinical course of the hospitalized infants was generally uncomplicated.

Infants hospitalized in intensive care units with 2009 H1N1 influenza infection, California, 2009-2010

BACKGROUND

The 2009 H1N1 influenza virus emerged in April 2009 and primarily affected children and young adults. Few reports describe 2009 H1N1 influenza infection in infants. This report describes the clinical and epidemiologic features of 2009 H1N1 influenza in critically ill infants younger than 1 year of age.

METHODS

Laboratory-confirmed cases were reported to the California Department of Public Health as part of public health surveillance for 2009 H1N1 influenza. Data were collected using standardized report forms and medical-chart abstractions.

RESULTS

From April 23, 2009 through May 1, 2010, 82 cases of infants hospitalized in the intensive care unit with 2009 H1N1 influenza were reported in California. Medical charts were available for 77 of the infants, whose median age was 109 days (range: 1-361 days). Twenty-seven (35%) infants had a gestational age of 36 weeks or less. More than half (46; 60%) of the infants had at least 1 reported chronic medical condition. Thirty-five (45%) infants required mechanical ventilation; 7 (9%) died. Five infants were hospitalized since birth and acquired influenza infection during their admission; 2 (40%) of these infants died.

CONCLUSIONS

Infants who are premature or with chronic conditions seem to be at increased risk for developing severe 2009 H1N1 influenza infection. We encourage clinicians to maintain high suspicion for influenza in infants when influenza viruses are circulating. Vaccination should be encouraged among contacts of infants <6 months of age, who are too young to be immunized or treated with licensed antivirals. Infection control measures should also be implemented in hospital settings to reduce nosocomial transmission.

Pandemic A/H1N1v influenza 2009 in hospitalized children: a multicenter Belgian survey

Background

During the 2009 influenza A/H1N1v pandemic, children were identified as a specific "at risk" group. We conducted a multicentric study to describe pattern of influenza A/H1N1v infection among hospitalized children in Brussels, Belgium.

Methods

From July 1, 2009, to January 31, 2010, we collected epidemiological and clinical data of all proven (positive H1N1v PCR) and probable (positive influenza A antigen or culture) pediatric cases of influenza A/H1N1v infections, hospitalized in four tertiary centers.

Results

During the epidemic period, an excess of 18% of pediatric outpatients and emergency department visits was registered. 215 children were hospitalized with proven/probable influenza A/H1N1v infection. Median age was 31 months. 47% had ≥ 1 comorbid conditions. Febrile respiratory illness was the most common presentation. 36% presented with initial gastrointestinal symptoms and 10% with neurological manifestations. 34% had pneumonia. Only 24% of the patients received oseltamivir but 57% received antibiotics. 10% of children were admitted to PICU, seven of whom with ARDS. Case fatality-rate was 5/215 (2%), concerning only children suffering from chronic neurological disorders. Children over 2 years of age showed a higher propensity to be admitted to PICU (16% vs 1%, p = 0.002) and a higher mortality rate (4% vs 0%, p = 0.06). Infants less than 3 months old showed a milder course of infection, with few respiratory and neurological complications.

Conclusion

Although influenza A/H1N1v infections were generally self-limited, pediatric burden of disease was significant. Compared to other countries experiencing different health care systems, our Belgian cohort was younger and received less frequently antiviral therapy; disease course and mortality were however similar.

Pandemic H1N1 influenza-associated hospitalizations in children in Madrid, Spain

OBJECTIVE

To describe the epidemiological and clinical characteristics of children hospitalized with 2009 pandemic influenza (pH1N1) in Madrid, Spain.

PATIENTS/METHODS

We included patients less than 14 years of age admitted to one of 18 hospitals in Madrid, Spain, between May 1 and November 30, 2009 and diagnosed with pH1N1 by polymerase chain reaction. A retrospective chart review was conducted and data were compared by age, presence of high-risk medical conditions, and pediatric intensive care unit (PICU) admission.

RESULTS

A total of 517 pH1N1 cases were included for final analysis. One hundred and forty-two patients (27·5%) had predisposing underlying illnesses, with immunosuppression (36 children, 7%) and moderate persistent asthma (34, 6·6%) being the most common ones. Patients with underlying medical conditions had longer hospital stays [median 5, interquartile range (IQR) 3-8 days, versus median 4, IQR 3-6, P < 0·001] and required intensive care (20·4% versus 5·9%, P < 0·001) and mechanical ventilation more frequently than previously healthy children. Globally, intensive care was required for 51 patients (10%) and invasive mechanical ventilation for 12 (2%). Pediatric intensive care unit admission was significantly associated with abnormal initial chest X-ray [Odds Ratio (OR) 3·5, 95% confidence interval (CI) 1·5-8·5], underlying neurological condition (OR 3·1, CI 1·2-7·5) and immunosuppression (OR 2·9, 1·2-6·8). Five patients (0·9%) died; two with severe neurological disease, two with leukemia, and one with a malignant solid tumor.

CONCLUSIONS

Children with underlying medical conditions experienced more severe pH1N1 disease. Risk factors for admission to the PICU included underlying neurological conditions, immunosuppression and abnormal initial chest X-ray.

Immunogenicity of trivalent influenza vaccine in extremely low-birth-weight, premature versus term infants

BACKGROUND

Influenza vaccine immunogenicity in premature infants is incompletely characterized.

OBJECTIVE

To assess the immunogenicity of trivalent, inactivated influenza vaccine (TIV) in extremely low-birth-weight (≤ 1000 g birth weight) premature (<30 weeks gestation) infants. We hypothesized that geometric mean titers of influenza antibody would be lower in premature than in full-term (FT) (≥ 37 week) infants.

DESIGN/METHODS

In this prospective multicenter study, former premature and FT infants who were 6 to 17 months of age received 2 doses of TIV during the 2006-2007 or 2007-2008 influenza seasons. Sera were drawn before dose 1, and 4 to 6 weeks after dose 2. Antibody was measured by hemagglutination inhibition.

RESULTS

Over 2 years, 41 premature and 42 FT infants were enrolled; 36 and 33 of these infants, respectively, had postvaccination titers available. Premature infants weighed less (mean, 1.3-1.8 kg difference) at the time of immunization than FT infants. Prevaccination titers did not differ between groups. Premature infants had higher postvaccination antibody geometric mean titers than FT infants to H1 (2006-2007, 1:513 vs. 1:91, P = 0.03; 2007-2008, 1:363 vs. 1:189, P = 0.02) and B/Victoria (2006-2007, 1:51 vs. 1:10, P = 0.02). More premature than FT infants had antibody titers ≥ 1:32 to B/Victoria (85% vs. 60%, P = 0.04) in 2007-2008. Two (5%) premature and 8 (19%) FT infants had adverse events, primarily fever, within 72 hours after vaccination. No child had medically diagnosed influenza.

CONCLUSIONS

Former premature infants had antibody responses to 2 TIV doses higher than or equal to those of FT children. Two TIV doses are immunogenic and well tolerated in extremely low-birth-weight, premature infants 6 to 17 months old.

Very low pandemic influenza A (H1N1) 2009 mortality associated with early neuraminidase inhibitor treatment in Japan: analysis of 1000 hospitalized children

OBJECTIVE

There were many cases of pandemic influenza A (H1N1) 2009 (H1N1/09) in Japan during the 2009-2010 epidemic. They accounted for 16% of the total population (20.7 million/128 million), and 59% of the patients were children 15 years of age and under (12.2 million/20.7million). However, there were only 38 paediatric deaths. We analyzed the clinical manifestations and treatment of children hospitalized because of H1N1/09 infection in order to clarify the association between treatment with neuraminidase inhibitors and the low mortality rate.

METHODS

A retrospective chart review was performed on a total of 1000 paediatric inpatients.

RESULTS

The causes of the hospitalizations were respiratory complications in 651 cases (65.1%), neurological complications in 255 cases (25.5%) and other complications in 94 cases. Neuraminidase inhibitors, primarily oseltamivir, had been used to treat 984 (98.4%) of the 1000 patients, and in 88.9% of the patients, treatment with neuraminidase inhibitors was initiated within 48 h after the onset of illness. Only 12 (1.2%) of the 1000 patients underwent mechanical ventilation, and one patient died of H1N1/09 infection.

CONCLUSIONS

Although a high proportion of the patients in this study had severe respiratory complications, the case fatality rate was only 0.1%. The low mortality rate of children due to the H1N1/09 epidemic in Japan was probably attributable to the universal implementation of early treatment with neuraminidase inhibitors.

Burden of severe 2009 pandemic influenza A (H1N1) infection in children in Southeast Spain

INTRODUCTION

Most of the published studies on patients admitted with 2009 pandemic influenza are not population based. We have compiled the clinical information regarding all children admitted with 2009 pandemic influenza A (H1N1) infection during the season 2009-2010 in our defined population, in order to have an unbiased view of the most severe side of the clinical spectrum of the infection and to quantify its burden.

METHODS

Children <15 years-old admitted to any of 3 hospitals in South-East Spain with 2009 pandemic influenza A (H1N1) detected by means of reverse transcriptase polymerase chain reaction. High quality data were extracted from clinical records specially designed for the pandemic.

RESULTS

Eighty two children fulfilled the inclusion criteria. The hospitalization rate was 68 per 100,000 children <15 years-old; in those <5 years-old the rate was of 131 and in <1 year-old, 234 per 100,000. An estimated 0.7% of the children who suffered from pandemic influenza were admitted (1.7% in <5 years-old). Intensive care was required for 5% of the hospitalized patients living in the study area. Mortality was roughly estimated about 1 per 100,000 children <15 years-old and was associated with the presence of very severe comorbidities or co-infections. Only 20% of the admitted children were ≥ 5 years-old and without risk factors. The disease followed a generally benign course despite the modest use of oseltamivir (49% of the patients).

CONCLUSIONS

Clinical and epidemiological data are very similar to those observed in other places and in interpandemic seasons with a high influenza activity.