Severe pediatric influenza in California, 2003-2005: implications for immunization recommendations

Ten Years of National Seasonal Surveillance for Severe Complications of Influenza in Australian Children

BACKGROUND

Severe complications of influenza in children are uncommon but may result in admission to hospital or an intensive care unit (ICU) and death.

METHODS

Active prospective surveillance using the Australian Paediatric Surveillance Unit with monthly reporting by pediatricians of national demographic and clinical data on children with <15 years of age hospitalized with severe complications of laboratory-confirmed influenza during ten influenza seasons 2008-2017.

RESULTS

Of 722 children notified, 613 had laboratory-confirmed influenza and at least one severe complication. Most (60%) were <5 years of age; 10% were <6 months, hence ineligible for vaccination. Almost half of all cases were admitted to ICU and 30 died. Most children were previously healthy: 40.3% had at least one underlying medical condition. Sixty-five different severe complications were reported; pneumonia was the most common, occurring in over half of all cases. Influenza A accounted for 68.6% hospitalizations; however, influenza B was more often associated with acute renal failure (P = 0.014), rhabdomyolysis (P = 0.019), myocarditis (P = 0.015), pericarditis (P = 0.013), and cardiomyopathy (P = 0.035). Children who died were more likely to be older (5-14 years), have underlying medical conditions, be admitted to ICU, and have encephalitis, acute renal failure, or myocarditis. Only 36.1% of all children reported received antiviral medications, and 8.5% were known to be vaccinated for seasonal influenza.

CONCLUSIONS

Severe influenza complications cause morbidity and mortality in children, which may increase if coinfection with COVID-19 occurs in the 2020 season and beyond. Increased vaccination rates, even in healthy children, early diagnosis and timely antiviral treatment are needed to reduce severe complications and death.

Australian Paediatric Surveillance Unit (APSU) Annual Surveillance Report 2019

The Australian Paediatric Surveillance Unit (APSU) has been prospectively collecting national data on rare childhood conditions since 1993, with monthly reporting of cases by paediatricians. In this report we describe annual results from studies for ten communicable diseases and complications of communicable diseases that were conducted using APSU surveillance in 2019 and place these in an historic context. Results are reported on acute flaccid paralysis, congenital cytomegalovirus infection, neonatal herpes simplex virus infection, perinatal exposure to HIV, paediatric HIV infection, severe complications of seasonal influenza, juvenile onset recurrent respiratory papillomatosis (JoRRP), congenital rubella syndrome, congenital varicella syndrome and neonatal varicella infection. APSU provides rich clinical data to complement data collected from other surveillance systems and to improve understanding and response to rare childhood infections.

Vaccine hesitancy and influenza beliefs among parents of children requiring a second dose of influenza vaccine in a season: An American Academy of Pediatrics (AAP) Pediatric Research in Office Settings (PROS) study

To receive adequate protection against influenza, some children 6 months through 8 y old need two doses of influenza vaccine in a given season. Currently, only half of those receiving the first dose receive a second. Our objective was to assess vaccine hesitancy and influenza disease and vaccine knowledge, attitudes, and beliefs among caregivers of children who received the first of their two needed doses. As part of a national-randomized control trial of second dose text-message influenza vaccine reminders (2017-2018 season), a telephone survey collected caregiver and index child demographic information. Each child had received the first of two needed influenza vaccine doses. Caregivers completed a measure of general vaccine hesitancy - the five-question Parent Attitudes About Childhood Vaccines Survey Tool (PACV-5) - and questions about influenza infection and vaccine. We assessed associations between participant demographic characteristics, vaccine hesitancy, and influenza beliefs and calculated the standardized proportion of caregivers endorsing each outcome using logistic regression. Analyses included responses from 256 participants from 36 primary care practices in 24 states. Some caregivers (11.7%) reported moderate/high vaccine hesitancy and many had misperceptions about influenza disease and vaccine. In multivariable models, no single variable was consistently associated with inaccurate knowledge, attitudes, and beliefs. These results demonstrate that caregivers whose children received the first dose of influenza vaccine may still be vaccine hesitant and have inaccurate influenza beliefs. Pediatricians should consider broadly addressing inaccurate beliefs and promoting vaccination even after caregivers agree to the first dose.

Antenatal Influenza A-Specific IgA, IgM, and IgG Antibodies in Mother's Own Breast Milk and Donor Breast Milk, and Gastric Contents and Stools from Preterm Infants

Antenatal milk anti-influenza antibodies may provide additional protection to newborns until they are able to produce their own antibodies. To evaluate the relative abundance of milk, we studied the antibodies specific to influenza A in feeds and gastric contents and stools from preterm infants fed mother’s own breast milk (MBM) and donor breast milk (DBM). Feed (MBM or DBM) and gastric contents (MBM or DBM at 1 h post-ingestion) and stool samples (MBM/DBM at 24 h post-ingestion) were collected, respectively, from 20 preterm (26–36 weeks gestational age) mother-infant pairs at 8–9 days and 21–22 days of postnatal age. Samples were analyzed via ELISA for anti-H1N1 hemagglutinin (anti-H1N1 HA) and anti-H3N2 neuraminidase (anti-H3N2 NA) specificity across immunoglobulin A (IgA), immunoglobulin M (IgM), and immunoglobulin G (IgG) isotypes. The relative abundance of influenza A-specific IgA in feeds and gastric contents were higher in MBM than DBM at 8–9 days of postnatal age but did not differ at 21–22 days. Anti-influenza A-specific IgM was higher in MBM than in DBM at both postnatal times in feed and gastric samples. At both postnatal times, anti-influenza A-specific IgG was higher in MBM than DBM but did not differ in gastric contents. Gastric digestion reduced anti-H3N2 NA IgG from MBM at 21–22 days and from DBM at 8–9 days of lactation, whereas other anti-influenza A antibodies were not digested at either postnatal times. Supplementation of anti-influenza A-specific antibodies in DBM may help reduce the risk of influenza virus infection. However, the effective antibody dose required to induce a significant protective effect remains unknown.

Maternal vaccination for the prevention of influenza: current status and hopes for the future

Influenza is an important cause of morbidity and mortality among pregnant women and young infants, and influenza infection during pregnancy has also been associated with adverse obstetric and birth outcomes. There is substantial evidence - from randomized trials and observational studies - that maternal influenza immunization can protect pregnant women and their infants from influenza disease. In addition, there is compelling observational evidence that prevention of influenza in pregnant women can also protect against certain adverse pregnancy outcomes, including stillbirth and preterm birth. In this article we will review and evaluate the literature on both the burden of influenza disease in pregnant women and infants, as well as the multiple potential benefits of maternal influenza immunization for mother, fetus, and infant. We will also review key clinical aspects of maternal influenza immunization, as well as identify remaining knowledge gaps, and discuss avenues for future investigation.

Influenza Vaccination During Pregnancy: Influenza Seasons 2002-2012, Vaccine Safety Datalink

INTRODUCTION

Pregnant women are at risk for influenza-related complications and have been recommended for vaccination by the Advisory Committee on Immunization Practices (ACIP) since 1990. Annual rates of influenza coverage of pregnant women have been consistently low. The Vaccine Safety Datalink was used to assess influenza vaccine coverage over 10 consecutive years (2002-2012); assess patterns related to changes in ACIP recommendations; identify predictors of vaccination; and compare the results with those published by national U.S. surveys.

METHODS

Retrospective cohort study of 721,898 pregnancies conducted in 2014. Coverage rates were assessed for all pregnancies and for live births only. Multivariate regression analysis identified predictors associated with vaccination.

RESULTS

Coverage increased from 8.8% to 50.9% in 2002-2012. Seasonal coverage rates increased slowly following the 2004 ACIP influenza vaccine recommendation (to remove the first trimester restriction), but spiked significantly during the 2009 H1N1 influenza pandemic. Significant predictors of vaccination during pregnancy included older age; vaccination in a previous season; high-risk conditions in addition to pregnancy; pregnancy during either the 2004-2005 or 2009-2010 seasons; entering the influenza season after the first trimester of pregnancy; and a pregnancy with longer overlap with the influenza season (p<0.001 for each).

CONCLUSIONS

Influenza vaccination coverage among pregnant women increased between the 2002-2003 and 2011-2012 seasons, although it was still below the developmental Healthy People 2020 goal of 80%. The 2004 ACIP language change positively impacted first-trimester vaccination uptake. Vaccine Safety Datalink data estimates were consistent with U.S. estimates.

Continued high incidence of children with severe influenza A(H1N1)pdm09 admitted to paediatric intensive care units in Germany during the first three post-pandemic influenza seasons, 2010/11-2012/13

BACKGROUND

Previous influenza surveillance at paediatric intensive care units (PICUs) in Germany indicated increased incidence of PICU admissions for the pandemic influenza subtype A(H1N1)pdm09. We investigated incidence and clinical characteristics of influenza in children admitted to PICUs during the first three post-pandemic influenza seasons, using active screening.

METHODS

We conducted a prospective surveillance study in 24 PICUs in Bavaria (Germany) from October 2010 to September 2013. Influenza cases among children between 1 month and 16 years of age admitted to these PICUs with acute respiratory infection were confirmed by PCR analysis of respiratory secretions.

RESULTS

A total of 24/7/20 influenza-associated PICU admissions were recorded in the post-pandemic seasons 1/2/3; incidence estimates per 100,000 children were 1.72/0.76/1.80, respectively. Of all 51 patients, 80% had influenza A, including 65% with A(H1N1)pdm09. Influenza A(H1N1)pdm09 was almost absent in season 2 (incidence 0.11), but dominated PICU admissions in seasons 1 (incidence 1.35) and 3 (incidence 1.17). Clinical data was available for 47 influenza patients; median age was 4.8 years (IQR 1.6-11.0). The most frequent diagnoses were influenza-associated pneumonia (62%), bronchitis/bronchiolitis (32%), secondary bacterial pneumonia (26 %), and ARDS (21%). Thirty-six patients (77 %) had underlying medical conditions. Median duration of PICU stay was 3 days (IQR 1-11). Forty-seven per cent of patients received mechanical ventilation, and one patient (2%) extracorporeal membrane oxygenation; 19% were treated with oseltamivir. Five children (11%) had pulmonary sequelae. Five children (11%) died; all had underlying chronic conditions and were infected with A(H1N1)pdm09. In season 3, patients with A(H1N1)pdm09 were younger than in season 1 (p = 0.020), were diagnosed more often with bronchitis/bronchiolitis (p = 0.004), and were admitted to a PICU later after the onset of influenza symptoms (p = 0.041).

CONCLUSIONS

Active screening showed a continued high incidence of A(H1N1)pdm09-associated PICU admissions in the post-pandemic seasons 1 and 3, and indicated possible underestimation of incidence in previous German studies. The age shift of severe A(H1N1)pdm09 towards younger children may be explained by increasing immunity in the older paediatric population. The high proportion of patients with underlying chronic conditions indicates the importance of consistent implementation of the current influenza vaccination recommendations for risk groups in Germany.

Promoting Vaccine Confidence

Vaccine hesitancy incorporates a wide range of parental attitudes and behaviors surrounding vaccines. Ironically, the very success of the immunization program has fueled vaccine concerns; because vaccine-preventable diseases are no longer prevalent, attention has shifted to the safety and necessity of vaccines themselves. This article reviews some of the underlying themes of vaccine hesitancy as well as specific vaccine safety concerns. Strategies for discussing vaccines with concerned parents are also discussed.

Adiposity and influenza-associated respiratory mortality: a cohort study

BACKGROUND

Obesity was first noted as a risk factor for severe illness associated with pandemic H1N1 infection in 2009, but the relationship between obesity and seasonal influenza remains unclear.

METHODS

We used data from a population-based cohort comprising 66 820 older (≥65 years) participants with a follow-up period from 1998 to 2012. The impact of influenza activity on respiratory mortality rates was estimated using a Cox proportional hazards model adjusted for comorbidities, meteorological factors, and other co-circulating respiratory viruses. We also tested whether the association of influenza with respiratory mortality varied with obesity and/or health status. As a control outcome, we similarly assessed the association of influenza with deaths from external causes, because these deaths should be unrelated to influenza.

RESULTS

Seasonal influenza activity was associated with higher respiratory mortality (hazard ratio [HR], 1.13 for influenza activity in the influenza season vs noninfluenza season; 95% confidence interval [CI], 1.05-1.22). The effect of seasonal influenza was 19% greater in obese individuals than normal-weight individuals (HR, 1.19; 95% CI, 1.01-1.42). The marginally significant and greater effect modification of obesity status on the association between seasonal influenza and respiratory mortality was also observed among older people in good health (HR, 1.35; 95% CI, .97-1.87). No such relations were observed for death from external causes.

CONCLUSIONS

Obesity aggravates the effect of seasonal influenza on respiratory mortality. Priority for influenza vaccine should be considered for obese older people to decrease the burden of influenza.

A multicenter outcomes analysis of children with severe rhino/enteroviral respiratory infection

OBJECTIVES

To investigate the impact of human rhino/enteroviruses on morbidity and mortality outcomes in children with severe viral respiratory infection.

DESIGN

Retrospective cohort study.

SETTING

The ICU, either PICU or cardiac ICU, at three urban academic tertiary-care children's hospitals.

PATIENTS

All patients with laboratory-confirmed human rhino/enteroviruses infection between January 2010 and June 2011.

INTERVENTIONS

We captured demographic and clinical data and analyzed associated morbidity and mortality outcomes.

MEASUREMENTS AND MAIN RESULTS

There were 519 patients included in our analysis. The median patient age was 2.7 years. The median hospital and ICU lengths of stay were 4 days and 2 days, respectively. Thirty-four percent of patients had a history of asthma, and 25% of patients had a chronic medical condition other than asthma. Thirty-two percent of patients required mechanical ventilation. Eleven patients (2.1%) did not survive to hospital discharge. The rate of viral coinfection was 12.5% and was not associated with mortality. Predisposing factors associated with increased mortality included immunocompromised state (p < 0.001), ICU admission severity of illness score (p < 0.001), and bacterial coinfection (p = 0.003).

CONCLUSIONS

There is substantial morbidity associated with severe respiratory infection due to human rhino/enteroviruses in children. Mortality was less severe than reported in other respiratory viruses such as influenza and respiratory syncytial virus. The burden of illness from human rhino/enteroviruses in the ICU in terms of resource utilization may be considerable.

Seasonal and Pandemic Influenza Surveillance and Disease Severity

Continuous investments in influenza research, surveillance, and prevention efforts are critical to mitigate the consequences of annual influenza epidemics and pandemics. New influenza viruses emerge due to antigenic drift and antigenic shift evading human immune system and causing annual epidemics and pandemics. Three pandemics with varying disease severity occurred in the last 100 years. The disease burden and determinants of influenza severity depend on circulating viral strains and individual demographic and clinical factors. Surveillance is the most effective strategy for appropriate public health response. Active and passive surveillance methods are utilized to monitor influenza epidemics and emergence of novel viruses. Meaningful use of electronic health records could be a cost-effective approach to improved influenza surveillance

Text message reminders for second dose of influenza vaccine: a randomized controlled trial

OBJECTIVE

To determine whether provision of vaccine-health-literacy-promoting information in text message vaccine reminders improves receipt and timeliness of the second dose of influenza vaccine within a season for children in need of 2 doses.

METHODS

During the 2012-2013 season, families of eligible 6-month through 8-year-old children were recruited at the time of their first influenza vaccination from 3 community clinics in New York City. Children (n = 660) were randomly assigned to "educational" text message, "conventional" text message, and "written reminder-only" arms. At enrollment, all arms received a written reminder with next dose due date. Conventional messages included second dose due date and clinic walk-in hours. Educational messages added information regarding the need for a timely second dose. Receipt of second dose by April 30 was assessed by using χ(2) tests. Timeliness was assessed by receipt of second dose by 2 weeks after due date (day 42) using χ(2) and over time using a Kaplan-Meier analysis.

RESULTS

Most families were Latino and publicly insured with no significant between-arm differences between groups. Children in the educational arm were more likely to receive a second dose by April 30 (72.7%) versus conventional (66.7%) versus written reminder-only arm (57.1%; P = .003). They also had more timely receipt by day 42 (P < .001) and over time (P < .001).

CONCLUSIONS

In this low-income, urban, minority population, embedding health literacy information improved the effectiveness of text message reminders in promoting timely delivery of a second dose of influenza vaccine, compared with conventional text messages and written reminder only.

Severe complications in influenza-like illnesses

OBJECTIVE

Data on complications from upper respiratory infection are limited. We examined development of severe complications in children presenting to the emergency department (ED) for moderate to severe influenza-like illness (ILI).

METHODS

Prospective cohort study of children 0 to 19 years presenting to a tertiary care children's hospital ED during peak respiratory viral seasons from 2008 to 2010. Subjects included had moderate to severe ILI, defined by performance of venipuncture and nasopharyngeal multiplex polymerase chain reaction for respiratory viruses. Severe complications (respiratory failure, encephalopathy, seizures, pneumonia, bacteremia, death) were prospectively determined. Risk factors for severe complications were collected, including demographics, comorbidities, and household exposures.

RESULTS

There were 241 enrolled subjects with median age of 27.4 months (interquartile range 8.9-68.5); 59.3% were boys and 48.5% were black. High-risk conditions were present in 53.5%. Severe complications developed in 35.3% (95% confidence interval [CI] 29.3-41.3), most frequently pneumonia (26.1%). The risk for severe complications was increased in subjects with neurologic or neuromuscular conditions (relative risk 4.0; 95% CI 1.9-8.2). No specific respiratory virus was associated with development of severe complications. Among patients with influenza, severe complications were greater with subtype H1N1 infection (relative risk 1.45, 95% CI 0.99-2.13, P = .048), and were at highest risk for pneumonia (relative risk 4.2, 95% CI 1.2-15.9).

CONCLUSION

In children presenting to the ED for moderate to severe ILI, those with neurologic and neuromuscular disease are at increased risk for severe complications. Development of severe complications did not differ by infecting virus; however, risk of severe complications was greater with subtype H1N1 compared with other influenza.

Influenza vaccination in children being treated with chemotherapy for cancer

BACKGROUND

Influenza infection is a potential cause of severe morbidity in children with cancer; therefore vaccination against influenza is recommended. However, data are conflicting regarding the immune response to influenza vaccination in children with cancer, and the value of vaccination remains unclear.

OBJECTIVES

1. To assess the efficacy of influenza vaccination in stimulating an immunological response in children with cancer during chemotherapy, compared with control groups.2. To assess the efficacy of influenza vaccination in preventing confirmed influenza and influenza-like illness and/or in stimulating immunological response in children with cancer treated with chemotherapy, compared with placebo, no intervention or different dosage schedules.3. To identify the adverse effects associated with influenza vaccines in children with cancer treated with chemotherapy, compared with other control groups.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (1966 to 2012) and EMBASE (1980 to 2012) up to August 2012. We also searched reference lists of relevant articles and conference proceedings of the Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC), the Infectious Diseases Society of America (IDSA), the Multinational Association of Supportive Care in Cancer (MASCC) and the International Society of Paediatric Oncology (SIOP).

SELECTION CRITERIA

We considered randomised controlled trials (RCTs) and controlled clinical trials (CCTs) in which the serological response to influenza vaccination of children with cancer was compared with that of control groups. We also considered RCTs and CCTs that compared the effects of influenza vaccination on clinical response and/or immunological response in children with cancer being treated with chemotherapy, compared with placebo, no intervention or different dosage schedules.

DATA COLLECTION AND ANALYSIS

Two independent review authors assessed the methodological quality of included studies and extracted the data.

MAIN RESULTS

We included 1 RCT and 9 CCTs (total number of participants = 770). None of the included studies reported clinical outcomes. All included studies reported on influenza immunity and adverse reactions to vaccination. In five studies, immune responses to influenza vaccine were compared in 272 children receiving chemotherapy and 166 children not receiving chemotherapy. In four studies, responses to influenza vaccine were assessed in 236 children receiving chemotherapy compared with responses in 142 healthy children. Measures used to assess immune responses included a four-fold rise in antibody titre after vaccination, development of a haemagglutination inhibition (HI) titre > 32 and pre- and post-vaccination geometric mean titres (GMTs). Immune responses in children receiving chemotherapy were consistently weaker (four-fold rise of 38% to 65%) than those in children who had completed chemotherapy (50% to 86%) and in healthy children (53% to 89%). In terms of adverse effects, 391 paediatric oncology patients received influenza vaccine, and the adverse effects described included mild local reactions and low-grade fever. No life-threatening or persistent adverse effects were reported.

AUTHORS' CONCLUSIONS

Paediatric oncology patients receiving chemotherapy are able to generate an immune response to the influenza vaccine, but it remains unclear whether this immune response protects them from influenza infection or its complications. We are awaiting results from well-designed RCTs addressing the clinical benefit of influenza vaccination in these patients.

Assessing parents' knowledge and attitudes towards seasonal influenza vaccination of children before and after a seasonal influenza vaccination effectiveness study in low-income urban and rural Kenya, 2010-2011

Background

Influenza vaccine is rarely used in Kenya, and little is known about attitudes towards the vaccine. From June-September 2010, free seasonal influenza vaccine was offered to children between 6 months and 10 years old in two Population-Based Infectious Disease Surveillance (PBIDS) sites. This survey assessed attitudes about influenza, uptake of the vaccine and experiences with childhood influenza vaccination.

Methods

We administered a questionnaire and held focus group discussions with parents of children of enrollment age in the two sites before and after first year of the vaccine campaign. For pre-vaccination focus group discussions, we randomly selected mothers and fathers who had an eligible child from the PBIDS database to participate. For the post-vaccination focus group discussions we stratified parents whose children were eligible for vaccination into fully vaccinated, partially vaccinated and non-vaccinated groups.

Results

Overall, 5284 and 5755 people completed pre and post-vaccination questionnaires, respectively, in Kibera and Lwak. From pre-vaccination questionnaire results, among parents who were planning on vaccinating their children, 2219 (77.6%) in Kibera and 1780 (89.6%) in Lwak said the main reason was to protect the children from seasonal influenza. In the pre-vaccination discussions, no parent had heard of the seasonal influenza vaccine. At the end of the vaccine campaign, of 18,652 eligible children, 5,817 (31.2%) were fully vaccinated, 2,073 (11.1%) were partially vaccinated and, 10,762 (57.7%) were not vaccinated. In focus group discussions, parents who declined vaccine were concerned about vaccine safety or believed seasonal influenza illness was not severe enough to warrant vaccination. Parents who declined the vaccine were mainly too busy [251(25%) in Kibera and 95 (10.5%) in Lwak], or their child was away during the vaccination period [199(19.8%) in Kibera; 94(10.4%) in Lwak].

Conclusion

If influenza vaccine were to be introduced more broadly in Kenya, effective health messaging will be needed on vaccine side effects and frequency and potential severity of influenza infection.

Viral infections in children with community-acquired pneumonia

Viral pathogens are commonly isolated from children with community-acquired pneumonia (CAP). Viruses like respiratory syncytial virus, human rhinovirus, human metapneumovirus, parainfluenza viruses, and influenza may act as sole pathogens or may predispose to bacterial pneumonia by a variety of mechanisms. New, emerging, or reemerging viral pathogens occasionally cause outbreaks of severe respiratory tract infection in children. The 2009–2010 H1N1 influenza virus pandemic resulted in increased rates of influenza-related hospitalizations and deaths in children. Rapid viral diagnostic tests based on antigen detection or nucleic acid amplification are increasingly available for clinical use and confirm the importance of viral infection in children hospitalized with CAP. Recently published guidelines for the management of CAP in children note that positive viral test results can modify clinical decision making in children with suspected pneumonia by allowing antibacterial therapy to be withheld in the absence of clinical, laboratory, or radiographic findings that suggest bacterial coinfection.

The disappearing seasonality of autism conceptions in California

BACKGROUND

Autism incidence and prevalence have increased dramatically in the last two decades. The autism caseload in California increased 600% between 1992 and 2006, yet there is little consensus as to the cause. Studying the seasonality of conceptions of children later diagnosed with autism may yield clues to potential etiological drivers.

OBJECTIVE

To assess if the conceptions of children later diagnosed with autism cluster temporally in a systematic manner and whether any pattern of temporal clustering persists over time.

METHOD

We searched for seasonality in conceptions of children later diagnosed with autism by applying a one-dimensional scan statistic with adaptive temporal windows on case and control population data from California for 1992 through 2000. We tested for potential confounding effects from known risk factors using logistic regression models.

RESULTS

There is a consistent but decreasing seasonal pattern in the risk of conceiving a child later diagnosed with autism in November for the first half of the study period. Temporal clustering of autism conceptions is not an artifact of composition with respect to known risk factors for autism such as socio-economic status.

CONCLUSION

There is some evidence of seasonality in the risk of conceiving a child later diagnosed with autism. Searches for environmental factors related to autism should allow for the possibility of risk factors or etiological drivers that are seasonally patterned and that appear and remain salient for a discrete number of years.

Influenza-associated illness is an important contributor to febrile convulsions in Danish children

OBJECTIVE

To determine the burden of febrile convulsions attributed to influenza like illness in a western country during ten influenza seasons.

METHODS

Based on national Danish registries, we explored the association between influenza like illness (ILI) activity and weekly number of hospital admittances for febrile convulsions in time-series analyses. We included data on 59,870 admissions for febrile convulsions in children between three months and five years of age in the period 1995-2005.

RESULTS

There was a significant relation between ILI-activity and number of children admitted for febrile convulsions with a systematic increase in admissions to pediatric wards about one week before the national surveillance system detected the corresponding rise in ILI-activity. The yearly number of admissions attributable to ILI varied from 11 to 47% of admissions and was highest during influenza epidemics. This was in particular observed in seasons when a new strain of influenza A/H3N2 was circulating. During these epidemics, influenza contributed to 29-47% of admissions.

CONCLUSIONS

Influenza like illness is associated with a considerable burden of febrile convulsions in children, most pronounced in years with epidemics. As febrile convulsions are just one of many complications contributing to the burden of influenza in children, this should be taken into consideration when planning a vaccination strategy for preventing influenza-related morbidity in younger children.

Clinical and socioeconomic impact of pediatric seasonal and pandemic influenza

Influenza is frequent among otherwise healthy day-care and school-aged children. Recent studies have demonstrated its significant effect on various outcome factors, including significantly more school and parental work absenteeism, and secondary illnesses among family members. Other studies have shown that the potential benefit of vaccinating children against influenza extends to other members of their families, thus supporting earlier economic modeling analyses of immunization programs. Although there are some differences in the clinical and socio-economic impact of seasonal and pandemic influenza, the benefits of vaccination are similar in both cases. The vaccination of otherwise healthy children may significantly reduce direct and indirect influenza-related costs, which supports the recommendation to make wider use of influenza vaccine in healthy children of any age in order to reduce the burden of infection on the community.

Respiratory syncytial virus infection in children with neuromuscular impairment

Clinically obvious reasons why children with neurological impairment (NMI) may be more severely affected in case of a viral respiratory tract infection include reduced vital capacity due to muscular weakness or spastic scoliosis, disturbed clearance of respiratory excretions (weak coughing and dysphagia), inability to comply actively with physiotherapeutic interventions, recurrent micro-aspirations (gastroesophageal reflux disease, vomiting related to coughing), a history of frequent exposure to antibiotics and health care institutions, colonization with resistant pathogens, impaired immunologic defence mechanisms due to severe malnutrition and cachexia, and early clinical deterioration in case of high fever with metabolic acidosis and hypercapnia, and maybe associated seizures or febrile convulsions.

Data from the literature suggests that in all children with NMI, who have to be hospitalized with severe clinical deterioration due to an airway infection, at least one specimen of nasopharyngeal secretions should be sent as soon as possible to a virologic laboratory to detect viral pathogens. Children with severe NMI and those mechanically ventilated for other reasons being hospitalized during the RSV season must be strictly protected against nosocomial RSV infection by means of standard and droplet precautions. Finally, children with severe NMI and age below 24 months of life should receive passive immunization with palivizumab following international recommendations.

The management of community-acquired pneumonia in infants and children older than 3 months of age: clinical practice guidelines by the Pediatric Infectious Diseases Society and the Infectious Diseases Society of America

Evidenced-based guidelines for management of infants and children with community-acquired pneumonia (CAP) were prepared by an expert panel comprising clinicians and investigators representing community pediatrics, public health, and the pediatric specialties of critical care, emergency medicine, hospital medicine, infectious diseases, pulmonology, and surgery. These guidelines are intended for use by primary care and subspecialty providers responsible for the management of otherwise healthy infants and children with CAP in both outpatient and inpatient settings. Site-of-care management, diagnosis, antimicrobial and adjunctive surgical therapy, and prevention are discussed. Areas that warrant future investigations are also highlighted.

Severe influenza cases in paediatric intensive care units in Germany during the pre-pandemic seasons 2005 to 2008

BACKGROUND

Data on complications in children with seasonal influenza virus infection are limited. We initiated a nation-wide three-year surveillance of children who were admitted to a paediatric intensive care unit (PICU) with severe seasonal influenza.

METHODS

From October 2005 to July 2008, active surveillance was performed using an established reporting system for rare diseases (ESPED) including all paediatric hospitals in Germany. Cases to be reported were hospitalized children < 17 years of age with laboratory-confirmed influenza treated in a PICU or dying in hospital.

RESULTS

Twenty severe influenza-associated cases were reported from 14 PICUs during three pre-pandemic influenza seasons (2005-2008). The median age of the patients (12 males/8 females) was 7.5 years (range 0.1-15 years). None had received vaccination against influenza. In 14 (70%) patients, the infection had been caused by influenza A and in five (25%) by influenza B; in one child (5%) the influenza type was not reported. Patients spent a median of 19 (IQR 12-38) days in the hospital and a median of 11 days (IQR 6-18 days) in the PICU; 10 (50%) needed mechanical ventilation. Most frequent diagnoses were influenza-associated pneumonia (60%), bronchitis/bronchiolitis (30%), encephalitis/encephalopathy (25%), secondary bacterial pneumonia (25%), and ARDS (25%). Eleven (55%) children had chronic underlying medical conditions, including 8 (40%) with chronic pulmonary diseases. Two influenza A- associated deaths were reported: i) an 8-year old boy with pneumococcal encephalopathy following influenza infection died from cerebral edema, ii) a 14-year-old boy with asthma bronchiale, cardiac malformation and Addison's disease died from cardiac and respiratory failure. For nine (45%) patients, possibly permanent sequelae were reported (3 neurological, 3 pulmonary, 3 other sequelae).

CONCLUSIONS

Influenza-associated pneumonia and secondary bacterial infections are relevant complications of seasonal influenza in Germany. The incidence of severe influenza cases in PICUs was relatively low. This may be either due to the weak to moderate seasonal influenza activity during the years 2005 to 2008 or due to under-diagnosis of influenza by physicians. Fifty% of the observed severe cases might have been prevented by following the recommendations for vaccination of risk groups in Germany.

Influenza vaccination, diagnosis, and treatment in children

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

Influenza vaccination coverage among pregnant women--National 2009 H1N1 Flu Survey (NHFS)

We sought to describe vaccination with influenza A (H1N1) 2009 monovalent (2009 H1N1) and trivalent seasonal (seasonal) vaccines among pregnant women during the 2009 through 2010 influenza season. A national H1N1 flu survey was conducted April through June 2010. The 2009 H1N1 and seasonal vaccination coverage estimates were 45.7% and 32.1%, respectively, among pregnant women aged 18-49 years. Receipt of a health care provider's recommendation for vaccination, perceived effectiveness of influenza vaccinations, and perceived high chance of influenza infection were independently associated with higher 2009 H1N1 and seasonal vaccination coverage. Pregnancy during October 2009 through January 2010 was independently associated with higher 2009 H1N1 vaccination coverage. The 2009 H1N1 vaccination level among pregnant women was higher than the seasonal vaccination level during the 2009 through 2010 season; it was also higher than vaccination among nonpregnant women with and without high-risk conditions. Health care providers and public health messaging played important roles in influencing vaccination behavior.

2009 Pandemic influenza A (H1N1) deaths among children--United States, 2009-2010

The 2009 pandemic influenza A (H1N1) (pH1N1) virus emerged in the United States in April 2009 (1) and has since caused significant morbidity and mortality worldwide (2-6). We compared pandemic influenza A (H1N1) (pH1N1)-associated deaths occurring from 15 April 2009 through 23 January 2010 with seasonal influenza-associated deaths occurring from 1 October 2007 through 14 April 2009, a period during which data collected were most comparable. Among 317 children who died of pH1N1-associated illness, 301 (95%) had a reported medical history. Of those 301, 205 (68%) had a medical condition associated with an increased risk of severe illness from influenza. Children who died of pH1N1-associated illness had a higher median age (9.4 vs 6.2 years; P<.01) and longer time from onset of symptoms to death (7 vs 5 days, P<.01) compared with children who died of seasonal influenza-associated illness. The majority of pediatric deaths from pH1N1 were in older children with high-risk medical conditions. Vaccination continues to be critical for all children, especially those at increased risk of influenza-related complications.

Clinical manifestations and socio-economic impact of influenza among healthy children in the community

OBJECTIVES

To evaluate the total burden of influenza among healthy children in the community in order to analyse the cost of influenza in paediatric age.

METHODS

This prospective study involved a total community population of 21,986 children, 6988 of whom experienced an influenza-like illness (ILI) between 1 November 2008 and 30 April 2009. An electronic chart was completed, a nasopharyngeal swab was obtained, and information was recorded concerning the clinical outcomes and household impact of the ILI episodes. Influenza A and B viruses were detected in all the swabs by means of polymerase chain reaction, and costs of the disease were calculated.

RESULTS

Influenza viruses were detected in 2143 cases (30.7%), an incidence of 96.4 per 1000 children. Influenza A and B viruses were found in respectively 1751 (81.7%) and 392 cases (18.3%). The mean cost of influenza was no less than €130, 32% higher than the cost of influenza-negative ILIs (p < 0.001). The influenza A cases were significantly more expensive than the influenza B cases (p < 0.001), and influenza in children aged <2 and 2-5 years was significantly more expensive than in children aged >5 years (p < 0.05). The differences were mainly related to the indirect costs of the parents' lost working days.

CONCLUSIONS

The findings of this study confirm that influenza among healthy children is important because of its frequency and its indirect consequences on the households of infected children, and support the use of influenza vaccination in healthy children aged between 6 months and 5 years.

Structural basis of influenza virus neutralization

Although seasonal influenza vaccines play a valuable role in reducing the spread of virus at the population level, ongoing viral evolution to evade immune responses remains problematic. No current vaccines elicit enduring protection in the face of emerging and re-emerging influenza viruses that are rapidly undergoing antigenic drift. Eliciting broadly cross-neutralizing antibody (nAb) responses against influenza virus is a crucial goal for seasonal and pandemic influenza vaccine preparation. Recent three-dimensional structure information obtained from crystallization of influenza antigens in complex with nAbs has provided a framework for interpreting antibody-based viral neutralization that should aid in the design of vaccine immunogens. Here, we will review current knowledge of the structure-based mechanisms contributing to the neutralization and neutralization escape of influenza viruses. We will also explore the potential for this structure-based approach to overcome the obstacles in developing the highly desired "universal" influenza vaccine.

Network analysis of global influenza spread

Although vaccines pose the best means of preventing influenza infection, strain selection and optimal implementation remain difficult due to antigenic drift and a lack of understanding global spread. Detecting viral movement by sequence analysis is complicated by skewed geographic and seasonal distributions in viral isolates. We propose a probabilistic method that accounts for sampling bias through spatiotemporal clustering and modeling regional and seasonal transmission as a binomial process. Analysis of H3N2 not only confirmed East-Southeast Asia as a source of new seasonal variants, but also increased the resolution of observed transmission to a country level. H1N1 data revealed similar viral spread from the tropics. Network analysis suggested China and Hong Kong as the origins of new seasonal H3N2 strains and the United States as a region where increased vaccination would maximally disrupt global spread of the virus. These techniques provide a promising methodology for the analysis of any seasonal virus, as well as for the continued surveillance of influenza.

Maternal influenza vaccination and effect on influenza virus infection in young infants

OBJECTIVE

To assess the effect of seasonal influenza vaccination during pregnancy on laboratory-confirmed influenza in infants to 6 months of age.

DESIGN

Nonrandomized, prospective, observational cohort study.

SETTING

Navajo and White Mountain Apache Indian reservations, including 6 hospitals on the Navajo reservation and 1 on the White Mountain Apache reservation.

PARTICIPANTS

A total of 1169 mother-infant pairs with mothers who delivered an infant during 1 of 3 influenza seasons.

MAIN EXPOSURE

Maternal seasonal influenza vaccination.

MAIN OUTCOME MEASURES

In infants, laboratory-confirmed influenza, influenza-like illness (ILI), ILI hospitalization, and influenza hemagglutinin inhibition antibody titers.

RESULTS

A total of 1160 mother-infant pairs had serum collected and were included in the analysis. Among infants, 193 (17%) had an ILI hospitalization, 412 (36%) had only an ILI outpatient visit, and 555 (48%) had no ILI episodes. The ILI incidence rate was 7.2 and 6.7 per 1000 person-days for infants born to unvaccinated and vaccinated women, respectively. There was a 41% reduction in the risk of laboratory-confirmed influenza virus infection (relative risk, 0.59; 95% confidence interval, 0.37-0.93) and a 39% reduction in the risk of ILI hospitalization (relative risk, 0.61; 95% confidence interval, 0.45-0.84) for infants born to influenza-vaccinated women compared with infants born to unvaccinated mothers. Infants born to influenza-vaccinated women had significantly higher hemagglutinin inhibition antibody titers at birth and at 2 to 3 months of age than infants of unvaccinated mothers for all 8 influenza virus strains investigated.

CONCLUSIONS

Maternal influenza vaccination was significantly associated with reduced risk of influenza virus infection and hospitalization for an ILI up to 6 months of age and increased influenza antibody titers in infants through 2 to 3 months of age.

Age, influenza pandemics and disease dynamics

The world is currently confronting the first influenza pandemic of the 21st century [caused by a novel pandemic influenza A (H1N1) virus]. Earlier pandemics have been characterized by age distributions that are distinct from those observed with seasonal influenza epidemics, with higher attack rates (and correspondingly increased proportionate or relative mortality) in younger individuals. While the genesis of protection against infection in older individuals during a pandemic is uncertain, differential vulnerability to infection by age has important implications for disease dynamics and control, and for choice of optimal vaccination strategies. Age-related vulnerability to infection may explain differences between school- and community-derived estimates of the reproductive number (R) for a newly emerged pandemic strain, and may also help explain the failure of a newly emerged influenza A (H1N1) virus strain to cause a pandemic in 1977. Age-related factors may also help explain variability in attack rates, and the size and impact of influenza epidemics across jurisdictions and between populations. In Canada, such effects have been observed in the apparently increased severity of outbreaks on Indigenous peoples' reserves. The implications of these patterns for vaccine allocation necessitate targeted research to understand age-related vulnerabilities early in an influenza pandemic.

Burden of influenza-related hospitalizations among children with sickle cell disease

OBJECTIVE

Children with sickle cell disease (SCD) are considered to be at high risk for complications from influenza infection despite minimal published data that characterize the burden of influenza in this population. Our objectives were to (1) estimate the rate of influenza-related hospitalizations (IRHs) among children with SCD, (2) compare this rate with rates of children with cystic fibrosis (CF) and children with neither SCD nor CF, and (3) explore mechanisms that underlie these potentially preventable hospitalizations.

METHODS

We analyzed hospitalizations from 4 states (California, Florida, Maryland, and New York) across 2 influenza seasons (2003-2004 and 2004-2005) from the Healthcare Cost and Utilization Project State Inpatient Databases. We included hospitalizations with a discharge diagnosis code for influenza in a child <18 years of age. We used census data and disease prevalence estimates to calculate denominators and compare rates of IRH among children with SCD, CF, and neither disease.

RESULTS

There were 7896 pediatric IRHs during the 2 influenza seasons. Of these, 159 (2.0%) included a co-occurring diagnosis of SCD. Annual rates of IRHs were 112 and 2.0 per 10 000 children with and without SCD, respectively, across both seasons. Children with SCD were hospitalized with influenza at 56 times (95% confidence interval: 48-65) the rate of children without SCD. Children with SCD had approximately double the risk of IRH compared with children with CF (risk ratio: 2.1 [95% confidence interval: 1.5-2.9]). IRHs among children with SCD were not longer, more costly, or more severe than IRHs among children without SCD; they were also rarely nosocomial and co-occurred with a diagnosis of asthma in 14% of cases.

CONCLUSIONS

IRHs are substantially more common among children with SCD than among those without the disease, which supports the potential importance of vigorous influenza vaccination efforts that target children with SCD.

Influenza virus infection among pediatric patients reporting diarrhea and influenza-like illness

Background

Influenza is a major cause of morbidity and hospitalization among children. While less often reported in adults, gastrointestinal symptoms have been associated with influenza in children, including abdominal pain, nausea, vomiting, and diarrhea.

Methods

From September 2005 and April 2008, pediatric patients in Indonesia presenting with concurrent diarrhea and influenza-like illness were enrolled in a study to determine the frequency of influenza virus infection in young patients presenting with symptoms less commonly associated with an upper respiratory tract infection (URTI). Stool specimens and upper respiratory swabs were assayed for the presence of influenza virus.

Results

Seasonal influenza A or influenza B viral RNA was detected in 85 (11.6%) upper respiratory specimens and 21 (2.9%) of stool specimens. Viable influenza B virus was isolated from the stool specimen of one case. During the time of this study, human infections with highly pathogenic avian influenza A (H5N1) virus were common in the survey area. However, among 733 enrolled subjects, none had evidence of H5N1 virus infection.

Conclusions

The detection of influenza viral RNA and viable influenza virus from stool suggests that influenza virus may be localized in the gastrointestinal tract of children, may be associated with pediatric diarrhea and may serve as a potential mode of transmission during seasonal and epidemic influenza outbreaks.

Enhanced immunogenicity of seasonal influenza vaccines in young children using MF59 adjuvant

BACKGROUND

Children have high morbidity and hospitalization rates from seasonal influenza. Meta-analyses suggest that conventional inactivated influenza vaccines are of low efficacy in young children, making vaccines that induce greater and broader immune protection in this vulnerable population a medical priority. Adjuvanted influenza vaccines may offer a solution.

SUBJECTS AND METHODS

Unprimed healthy children (6 to <36 months) were enrolled in an observer-blinded study and randomly assigned to receive 2 doses of MF59-adjuvanted vaccine (Sub/MF59, n = 130) or nonadjuvanted split vaccine (split, n = 139); subgroups of these (n = 43 and 46, respectively) received a booster dose 1 year later. Safety and clinical tolerability were assessed after each dose. Hemagglutination inhibition antibody titers were measured against influenza A and B strains included in the formulation of the vaccines and against mismatched strains.

RESULTS

Clinical tolerability and safety were generally comparable between vaccine groups, though some transient, mild solicited reactions were more frequent in the Sub/MF59 group. Postvaccination hemagglutination inhibition antibody titers to all 3 vaccine strains were significantly higher with Sub/MF59 than with split vaccine (all comparisons P < 0.001) after each of the 3 vaccine doses. In addition, Sub/MF59 induced significantly higher cross-reactivity against A/H3N2 and A/H1N1 mismatched strains.

CONCLUSION

MF59-adjuvanted influenza vaccine was well tolerated in healthy young children after each of 3 doses and induced greater, longer-lasting, and broader immune responses than a nonadjuvanted split vaccine. The enhanced immunogenicity of the adjuvanted vaccine was most evident in very young children and for the B vaccine strain.

Effects of oseltamivir on influenza-related complications in children with chronic medical conditions

OBJECTIVE

This study investigated the influence of oseltamivir on influenza-related complications and hospitalizations for children and adolescents, 1 to 17 years of age, with chronic medical conditions or neurologic or neuromuscular disease.

METHODS

In a retrospective study, outcomes for patients who were given oseltamivir within 1 day after influenza diagnosis were compared with those for patients who received no antiviral therapy. Anonymous data from MarketScan databases (Thomson Reuters, Cambridge, MA) were used to identify patients from 6 influenza seasons between 2000 and 2006. The study outcomes were frequencies of pneumonia, respiratory illnesses other than pneumonia, otitis media, and hospitalization.

RESULTS

Oseltamivir was prescribed for 1634 patients according to the study criteria, and 3721 patients received no antiviral therapy for their influenza. After adjustment for demographic and medical history variables, oseltamivir was associated with significant reductions in the risks of respiratory illnesses other than pneumonia, otitis media and its complications, and all-cause hospitalization in the 14 days after influenza diagnosis. Analyses for 30 days after influenza diagnosis also showed significant risk reductions for respiratory illnesses other than pneumonia, otitis media and its complications, and all-cause hospitalization with oseltamivir.

CONCLUSION

When it was prescribed at influenza diagnosis, oseltamivir was associated with reduced risks of influenza-related complications and hospitalizations for children and adolescents at high risk of influenza complications.

Influenza vaccination coverage among Spanish children, 2006

OBJECTIVES

Traditionally, influenza is not considered to be a serious disease in healthy children. However, for vulnerable populations, such as young children and those with chronic medical conditions, influenza can lead to serious complications and even death. This study aimed to assess vaccination coverage among Spanish children under 16 years of age in 2006, and to describe the factors associated with vaccination.

STUDY DESIGN

Cross-sectional survey.

METHODS

In total, 8851 records of children included in the Spanish National Health Survey for 2006 were analysed. The reply ('yes' or 'no') to the question: 'Did you have a flu shot in the latest campaign?' was used as a dependent variable. Influenza vaccine coverage was calculated as the percentage of individuals aged 6 months to 16 years whose parents reported that they had been vaccinated against influenza in the most recent campaign. The influence of sociodemographic variables on vaccination and the presence of associated chronic diseases (asthma and/or diabetes) were also analysed.

RESULTS

Vaccination coverage among Spanish children in 2006 was 6.82%: 19.43% in children with associated conditions (asthma and/or diabetes), and 5.81% in healthy children. The only factor significantly associated with influenza vaccination in children with associated conditions was household income; children with a lower household monthly income were more likely to have been vaccinated against influenza than children with a higher household monthly income (odds ratio 1.96). In children for whom vaccination is not indicated, the probability of being vaccinated against influenza was greater in those whose parents were not university graduates.

CONCLUSION

Influenza vaccination coverage in Spanish children is low. Socio-economic inequalities continue to be a factor at the time of vaccination.

Immunogenicity and safety of intradermal versus intramuscular route of influenza immunization in infants less than 6 months of age: a randomized controlled trial

We aimed to explore intradermal influenza vaccination in infants <6 months. One hundred twenty-six infants 2-3 months of age were randomized to receive either two doses, 1 month apart, of 0.25 ml of a trivalent inactivated influenza vaccine (7.5 microg of hemagglutinin per strain) via the intramuscular (IM) route or 0.1 ml of the same vaccine (3 microg of hemagglutinin per strain) via the intradermal (ID) route. The vaccine was well tolerated. Only four infants had hemagglutination inhibition (HAI) titer <40 against > or =1 vaccine-covered antigen pre-vaccination. There was no difference in fold-rise of HAI titer response between those in the IM or ID group. We documented maintenance of HAI titers above seroprotective levels against all three vaccine antigens in 97.6% of subjects regardless of vaccination methods over a time of waning maternal antibodies.

Influenza-associated hospitalization in urban Thai children

BACKGROUND

Studies in North America and Europe have shown that young children are at increased risk of serious complications and hospitalization from influenza infection. In Thailand, however, influenza is commonly considered a mild infection that rarely requires hospitalization. An improved understanding of the burden of serious complications from influenza infection in young children is needed to inform clinical treatment and vaccination guidelines.

METHODS

We conducted a prospective study of children 0-5 years of age with lower respiratory tract infection or influenza-like illness admitted to a pediatric tertiary-care hospital in Bangkok, Thailand during July 2004 to July 2005. All respiratory specimens were tested for influenza using a rapid antigen test and tissue cell culture.

RESULTS

Thirty-nine of 456 (8.6%) hospitalized children had culture-positive influenza. Eighty percent of hospitalized influenza patients had no underlying chronic illnesses. Nineteen (49%) influenza patients required hospital stays of 5 days or more and two patients required mechanical ventilation. Influenza activity demonstrated bimodal seasonal variation with peak activity from August to October and January to April. Cough was present in 38 (97%) cases and fever >38.5 degrees C was significantly associated with influenza.

CONCLUSION

Influenza is an important cause of hospitalization in children <5 years of age in Thailand. Children <5 years should be considered as a target group when establishing clinical guidelines for antiviral treatment and influenza vaccination.

Influenza vaccination in children being treated with chemotherapy for cancer

BACKGROUND

Influenza infection is a potential cause of severe morbidity in children with cancer, therefore vaccination against influenza is recommended. However, there are conflicting data concerning the immune response to influenza vaccination in children with cancer and the value of vaccination remains unclear.

OBJECTIVES

1. To assess the efficacy of influenza vaccination in stimulating immunological response in children with cancer during chemotherapy, compared to control groups. 2. To assess the efficacy of influenza vaccination in preventing confirmed influenza and influenza-like illness and/or stimulating immunological response in children with cancer treated with chemotherapy, compared to placebo, no intervention or different dosage schedules. 3. To determine the adverse effects associated with influenza vaccination in children with cancer.

SEARCH STRATEGY

We searched CENTRAL, MEDLINE (1966 to 2007) and EMBASE (1980 to 2007) up to February 2007. We also searched reference lists of relevant articles and conference proceedings of ICAAC, IDSA, MASCC and SIOP.

SELECTION CRITERIA

We considered randomised controlled trials (RCTs) and controlled clinical trials (CCTs) in which the serologic response to influenza vaccination of children with cancer was compared to other control groups. We also considered RCTs and CCTs comparing the effects of influenza vaccination on clinical response and/or immunological response in children with cancer, with placebo, no intervention or different dosage schedules.

DATA COLLECTION AND ANALYSIS

Two independent authors assessed the methodological quality of included studies and extracted data.

MAIN RESULTS

We included 1 RCT and 8 CCTs ( total number of participants=708). None of the included studies reported on clinical outcome. All included studies reported on influenza immunity and adverse reactions to vaccination. In five studies, immune responses to influenza vaccine were compared in 272 children on chemotherapy with 166 children not on chemotherapy. In three studies, responses to influenza vaccine were assessed in 204 children on chemotherapy compared with responses in 112 healthy children. The measures used to assess immune responses were: a four-fold rise in antibody titre after vaccination, development of haemagglutination inhibition (HI) titre > 32, and pre- and post-vaccination geometric mean titres (GMT). Immune responses in children receiving chemotherapy were consistently weaker (four-fold rise of 25% to 52%) than in those children who had completed chemotherapy (50% to 86%) and in healthy children (71% to 89%). Concerning adverse effects, 359 paediatric oncology patients received influenza vaccine and the side effects described were mild local reactions and low grade fever. No life-threatening or persistent adverse effects were reported.

AUTHORS' CONCLUSIONS

Paediatric oncology patients receiving chemotherapy are able to generate an immune response to the influenza vaccine, but it remains unclear whether this immune response protects them from influenza infection or its complications. We are awaiting results from well-designed RCTs addressing the clinical benefit of influenza vaccination in these patients.

Seasonal influenza in adults and children--diagnosis, treatment, chemoprophylaxis, and institutional outbreak management: clinical practice guidelines of the Infectious Diseases Society of America

Guidelines for the treatment of persons with influenza virus infection were prepared by an Expert Panel of the Infectious Diseases Society of America. The evidence-based guidelines encompass diagnostic issues, treatment and chemoprophylaxis with antiviral medications, and issues related to institutional outbreak management for seasonal (interpandemic) influenza. They are intended for use by physicians in all medical specialties with direct patient care, because influenza virus infection is common in communities during influenza season and may be encountered by practitioners caring for a wide variety of patients.

The risk of seasonal and pandemic influenza: prospects for control

Seasonal influenza is an underappreciated cause of morbidity and mortality in the United States. Seasonal vaccination of individuals in groups at high risk of complications has long been recommended. However, there has been a gradual expansion of the recommended groups for annual influenza immunization in order to reduce the incidence of uncomplicated infection, to alleviate the impact of seasonal influenza on health care, and to simplify the application of recommendations. The threat of an influenza pandemic, heightened by recent cases of highly pathogenic avian influenza in humans, requires continued efforts in preparedness. Strategies for the control of pandemic influenza must include vaccines, antiviral drugs, and nonpharmaceutical interventions like school closure and voluntary quarantine around cases. The prophylactic efficacy of neuraminidase inhibitors, previously observed in household studies, suggests that they will be a useful adjunct to voluntary quarantine. Stockpiles of antiviral drugs are being established for therapeutic and perhaps preventive use for pandemic influenza.

[Organization of intensive care in situation of avian flu pandemic]

The influenza pandemic will create a major increase in demand for hospital admissions, particularly for critical care services. The recommendations detailed herein have been elaborated by experts from medical societies potentially involved in this situation and focus on general hospital organization. Intensive care units will initially face high demand for admission; the Healthcare Authorities must therefore study how ICU capacity can be expanded. Pediatric intensive care units will be particularly affected by this situation of relative bed shortage, since young children, particularly infants, are expected to be affected by severe clinical forms of avian flu. Therefore, the weight threshold for admission to the adult ICU was lowered to 20 kg. Neonatal intensive care units (NICU) should remain, if possible, low viral density areas. Mixed (neonatal and pediatric) intensive care units could be dedicated to infants and children only. NICU admission of extreme premature babies should be limited in this difficult situation. Pediatric intensive care units (PICU) admission capacity could be doubled by using intermediate care and postoperative care units. The staff could be increased by doctors and nurses involved in canceled programmed activities. Healthcare workers transferred to PICU should be given special training.

[The organisation of intensive care in a situation of pandemic avian influenza]

The development of an epidemic of avian influenza will have a major impact on the organisation and structure of the facilities for treatment. This paper, the product of collaboration between the six learned societies concerned, analyses the impact of a possible pandemic on the various aspects of management of patients requiring intensive care. It describes the organisation of hospital pathways for flu and non-flu patients with, in particular, the necessary actions in terms of separation of care facilities, the triage of patients and the cancellation of non-urgent activities. It analyses the preconditions necessary for the efficient functioning of intensive care and the predictable limiting factors. It underlines the importance of training of medical and paramedical personnel. Finally, it tackles the specific problems of paediatric intensive care: organisation, capacity for admissions and training.

Prevention of influenza: recommendations for influenza immunization of children, 2007-2008

The American Academy of Pediatrics recommends annual influenza immunization for all children with high-risk conditions who are 6 months of age and older, for all healthy children ages 6 through 59 months, for all household contacts and out-of-home caregivers of children with high-risk conditions and of healthy children younger than 5 years, and for all health care professionals. To more fully protect against the morbidity and mortality of influenza, increased efforts are needed to identify and immunize all children at high risk and all healthy children ages 6 through 59 months and to inform their parents when annual immunizations are due. Previously unimmunized children who are at least 6 months of age but younger than 9 years should receive 2 doses of influenza vaccine, given 1 month apart, beginning as soon as possible on the basis of local availability during the influenza season. If children in this cohort received only 1 dose for the first time in the previous season, it is recommended that 2 doses be administered in the current season. This recommendation applies only to the influenza season that follows the first year that a child younger than 9 years receives influenza vaccine. A child who then also fails to receive 2 doses the next year should be given only 1 dose per year from that point on. Influenza vaccine should also continue to be offered throughout the influenza season, even after influenza activity has been documented in a community. On the basis of global surveillance of circulating virus strains, the influenza vaccine may change from year to year; indeed, 1 of the 3 strains in the 2007-2008 vaccine is different from the previous year's vaccine. All health care professionals, influenza campaign organizers, and public health agencies should develop plans for expanding outreach and infrastructure to immunize all children for whom influenza vaccine is recommended. Appropriate prioritization of administering influenza vaccine will also be necessary when vaccine supplies are delayed or limited. Because the influenza season often extends into March, immunization against influenza is recommended to continue through late winter and early spring. Lastly, it is recommended that for the 2007-2008 season, and likely beyond, health care professionals do not prescribe amantadine or rimantadine for influenza treatment or chemoprophylaxis, because widespread resistance to these antiviral medications now exists among influenza A viral strains. However, oseltamivir and zanamivir can be prescribed for treatment or chemoprophylaxis, because influenza A and B strains remain susceptible.

Creating a model program for influenza surveillance in California: results from the 2005-2006 influenza season

BACKGROUND

Influenza surveillance is valuable for monitoring trends in influenza-related morbidity and mortality. Using the 2005-2006 influenza season as an example, this paper describes a comprehensive influenza surveillance program used by the California Department of Public Health (CDPH).

METHODS

Data collected from patients evaluated for acute respiratory illness in a given week were reported and summarized the following week, including (1) electronic hospital pneumonia and influenza admission and antiviral usage records from Kaiser Permanente, (2) sentinel provider influenza-like illness (ILI) reports, (3) severe pediatric influenza case reports (e.g., children either hospitalized in intensive care or expired), (4) school clinic ILI evaluations, and (5) positive influenza test results from a network of academic, hospital, commercial, and public health laboratories and the state CDPH Viral and Rickettsial Disease Laboratory.

RESULTS

Influenza activity in California in the 2005-2006 season was moderate in severity; all clinical and laboratory markers rose and fell consistently. Extensive laboratory characterization identified the predominant circulating virus strain as A/California/7/2004(H3N2), which was a component of the 2005-2006 influenza vaccine; 96% of samples tested showed adamantane resistance.

CONCLUSIONS

By using multiple, complementary surveillance methods coupled with a strong laboratory component, the CDPH has developed a simple, flexible, stable, and widely accepted influenza surveillance system that can monitor trends in statewide influenza activity, ascertain the correlation between circulating strains with vaccine strains, and assist with detection of new strain variants. The methods described can serve as a model for influenza surveillance in other states.