Influenza and hospitalizations in children

Validity of parental report of influenza vaccination in young children seeking medical care

BACKGROUND

Despite frequent use of self-reported information to determine pediatric influenza vaccination coverage, little data are available on the validity of parental reporting of their child's influenza vaccination status and on factors affecting its accuracy.

METHODS

We compared parent reported influenza vaccination of children to documented reports of vaccination collected from medical records (the criterion standard) among children aged 6-59 months who presented to selected hospitals, emergency departments, and clinics in three U.S. counties with acute respiratory illness during three influenza seasons (November through May of 2004-2007). Demographic and epidemiologic data were collected from chart reviews and parental surveys.

RESULTS

Among 3072 children aged 6-59 months, 47.5% were reported by the parent to have received influenza vaccine and 39.5% of children had medical record verification of influenza vaccination. Sensitivity and specificity of parental reporting was 92.1% and 82.3%, respectively, when compared to the immunization record. However, 17.7% of children whose parents reported vaccination had no influenza vaccination documented in their medical records, and this proportion was even higher at 28.6%, among children with an underlying high-risk medical condition. Greater reporting accuracy was associated with younger age of child (6-23 months vs. 24-59 months), white non-Hispanic race/ethnicity, having health insurance, and having a mother with a college education.

CONCLUSIONS

Our findings indicate that although parental report of influenza vaccination is fairly reliable (∼76-96%), over reporting by parents often occurs and immunization record review remains the preferable method for determining vaccination status in children.

Hospital admissions related to influenza in France during the 2006/2007 epidemic

BACKGROUND

The data available on hospital admissions related to influenza mostly concern in-patients admitted via the emergency department. Severe cases have been collated by intensive care practitioners since 2009. For this survey, we searched French hospital admission databases to estimate the prevalence rate of hospital admissions related to influenza and to record qualitative data.

METHOD

All case studies identified between October 2006 and September 2007 were split into two groups: the first displaying symptoms of clinical influenza and the second suffering from influenza as an associated diagnosis.

RESULTS

We collected 6797 hospital admissions, 2126 of which were closely related to clinical influenza. Fifty percent of cases concerned the elderly and young people. Fifty-six hospital deaths were recorded in which influenza was the underlying cause in 21% of the cases (12). When influenza was an associated diagnosis (44/56), cardiovascular or respiratory diseases were the main causes (26/44).

CONCLUSION

During the same period (2006-2007), the French Sentinel Surveillance identified only 105 hospital admissions related to influenza. Our survey was therefore more exhaustive and was able to record qualitative data. Inclusion of hospital admissions with an associated diagnosis of influenza is debatable because this decreases specificity. The relationship between the principal diagnosis and all the associated diagnoses is difficult to study, although exclusion of this type of hospitalization could significantly underestimate these figures. Despite certain limitations, French hospital admissions databases should complement French Sentinel Surveillance data.

Safety of live attenuated influenza vaccine in mild to moderately immunocompromised children with cancer

BACKGROUND

The safety of intranasal live-attenuated influenza vaccine (LAIV) in immunocompromised children with cancer is unknown. The objective of this study was to describe the safety and immunogenicity of LAIV in mild to moderately immunocompromised children with cancer.

METHODS

We conducted a multicenter, randomized, double-blind study of LAIV versus placebo in children aged 5-17 years with cancer. LAIV (frozen formulation) or allantoic fluid/buffer was administered intranasally. Reactogenicity, adverse events, blood for immune assays, and nasal swabs for viral shedding were obtained during 5 visits over the first 42 days postvaccination; information concerning serious adverse events (SAEs) was collected for 180 days.

RESULTS

20 subjects were enrolled (LAIV, n=10; placebo, n=10) with a mean age of 12.2 years. Ten subjects had hematologic malignancy (LAIV, n=4; placebo, n=6); 10 subjects had solid tumors (LAIV, n=6; placebo, n=4). One subject was excluded from immunogenicity analysis for not receiving a full dose of LAIV. LAIV resulted in an increased incidence of runny nose/nasal congestion occurring in all LAIV recipients; no related SAEs were observed. Four of 10 LAIV recipients shed vaccine virus, with none exceeding 7-10 days duration. LAIV demonstrated modest immunogenicity by hemagglutination inhibition (≥ 4 fold rise for any strain, 33%) and microneutralization assays (≥ 4 fold rise for any strain, 44%).

CONCLUSION

In this small pilot study conducted in mild to moderately immunocompromised children with cancer, runny nose/nasal congestion was increased in LAIV recipients, no related SAEs occurred, and prolonged viral shedding was not detected. Moderate immunogenicity was demonstrated in this small group of individuals.

Influenza-related hospitalisations in children

AIM

To describe the disease burden, clinical pattern and outcome of influenza-related hospitalisations in children.

METHODS

This is a retrospective study carried out in a regional hospital in Hong Kong. Children hospitalised with established diagnosis of influenza infection from January to June of 2005 were studied. Length of hospitalisation, demographic characteristics, symptoms, clinical diagnosis and complications of influenza infection were analysed.

RESULTS

Influenza A infection accounted for 93.5% of these hospitalisations. Children less than 5 years of age comprised 70% of admission. Highest rate of admission occurred in May and April. One fourth of emergency admission during the study period and over 70% in the peak season was a result of influenza-related illness. Underlying medical disease was observed in 14.6% of children. Mean duration of hospitalisation was 3.0 days. Fever was the commonest presenting symptoms. Fever lasting for 7 days or more was observed in one-fifth of patients. Respiratory tract diseases (upper and lower) were the most frequent non-neurological diagnosis. Febrile convulsion was the complication observed in 27.6% of admission. One patient died as a result of acute necrotising encephalopathy.

CONCLUSION

Influenza contributed to heavy health-care burden. Mortality was rare but did occur. Hospitalisations occurred in both healthy children and those with underlying chronic illness. Young children played an important role in such hospitalisations. Means to prevent influenza-associated morbidity and mortality especially among young children are needed.

A personnel time-motion study of intranasal influenza vaccination in healthy children

Vaccinating millions of Americans depends, in part, on short vaccination times. During two intranasal influenza vaccine trials, times for six vaccination steps were recorded for 497 children. The total of mean times for the steps was 115 s, almost half spent explaining the vaccine and intranasal delivery. Intranasal influenza vaccination time showed little variation by patient age, was comparable to reported intramuscular vaccination times, and was a small fraction of the visit time. Total family visit time decreased by 64 s if the youngest child was receiving a second dose. Alternative delivery systems (e.g., group visits) are needed to take advantage of short vaccination times.

Immunisation in the current management of cystic fibrosis patients

Although no special recommendations exist, clearly patients with cystic fibrosis (CF) can benefit from immunisation. We reviewed the literature regarding vaccination in CF and other chronic diseases. CF subjects should follow national immunisation programmes without delay to obtain optimal vaccination coverage. Indeed they may escape normal programmes due to frequent hospital admissions and school absenteeism and may be more at risk to get "vaccine-controlled" diseases at any age. There is no uniform European immunisation schedule for basic infant and childhood vaccines or for vaccines against hepatitis A (HAV) and B (HBV), varicella (VZ) and booster vaccinations. HAV and HBV vaccination is appropriate in CF as recommended in general for patients with chronic liver disease (CLD). Varicella (VZ) vaccination is not recommended in all European countries. There are no recent data about possible worsening of pulmonary status following VZ in CF, but it is known to cause pulmonary damage in non-CF adults and to be potentially fatal post transplantation and during steroid treatment. Therefore it is recommended at least for seronegative adolescents and transplant candidates. Influenza vaccine is recommended annually for CF patients aged > or =6 months. Pneumococcal vaccine is generally indicated for CF patients. RSV infection might play a role in the initial Pseudomonas colonization and the decline in pulmonary function. However no RSV vaccine is available at present. There are no recommendations for palivizumab in CF as an alternative but expensive prophylaxis. Anti-bacterial vaccinations protecting directly against Pseudomonas aeruginosa colonisation are promising for the future, potential candidates are currently being assessed in phase III clinical trials. More studies are needed to complete recommendations especially for CF adults and transplant candidates.

Lower respiratory tract illness and RSV prophylaxis in very premature infants

AIMS

To determine the frequency of and the risk factors for readmissions for any lower respiratory tract illness (LRTI) and for respiratory syncytial virus (RSV) documented LRTI in children born very prematurely who had or had not received RSV prophylaxis.

METHODS

Multicentre prospective longitudinal cohort study of 2813 infants, born between April 2000 and December 2000 at less than 33 weeks of gestational age, and followed until the end of the epidemic season.

RESULTS

Among the 2256 children who had no bronchopulmonary dysplasia at 36 weeks of postmenstrual age and were not submitted to RSV prophylaxis, 27.4% were readmitted at least once for any reason during the epidemic season; 15.1% and 7.2% were readmitted at least once for any LRTI and RSV related LRTI, respectively. Children born at less than 31 weeks' gestation, having an intrauterine growth restriction, or living in a single mother family were at a significantly higher risk of readmission for LRTI in general as well as for RSV related LRTI. Of the 376 children submitted to prophylaxis, 28.2% were readmitted at least once for any LRTI and 6.1% for RSV related LRTI.

CONCLUSION

One out of four children who had received no prophylaxis, was born very prematurely, and was without bronchopulmonary dysplasia at 36 weeks of postmenstrual age, was readmitted at least once for any reason. Roughly 50% and 20% of these readmissions were related to a LRTI and an RSV infection, respectively. Further epidemiological studies are warranted to assess the aetiology and impact of other respiratory pathogens on post-discharge readmission and respiratory morbidity in this population.

Risk factors associated with severe influenza infections in childhood: implication for vaccine strategy

Infections caused by influenza virus lead to an excess rate of hospitalization of children during winter months. Current recommendations for vaccination target only children >6 months who belong to specific risk groups.

OBJECTIVE

To identify possible benefits of universal influenza vaccination, this study aims to determine characteristics of children hospitalized at the Montreal Children's Hospital (MCH) because of an infection attributable to influenza virus as well as risk factors associated with hospitalization.

METHODS

We retrospectively reviewed records of all children with a laboratory-proven diagnosis of influenza seen at MCH between April 1, 1999, and April 1, 2002. Data were analyzed using the Student t test and logistic regression.

RESULTS

We identified 182 patients hospitalized because of influenza and 114 patients who were not. Admission diagnoses were suspected sepsis (31%), lower respiratory tract infections (27%), and asthma or bronchiolitis (15%). Mean age of hospitalized patients was 26.1 month (median: 12 months), which was similar to that of patients not hospitalized, and 34% were <6 months. Seventy percent of those hospitalized did not have any underlying medical disorder and only 18% (33) were vaccine candidates according to current recommendations. Of the latter, less than half had been vaccinated. Factors associated with hospitalization were age <12 months (odds ratio [OR]: 2.3; 95% confidence interval [CI]: 1.1-4.8), male gender (OR: 1.9; 95% CI: 1.0-3.7), dehydration (OR: 4.3; 95% CI: 1.2-16.0), and decreased oxygen saturation (OR: 32.1; 95% CI: 4.1-249).

CONCLUSIONS

Considering that the majority of children hospitalized for influenza do not belong to the specific risk groups targeted by current recommendations, and that one third are <6 months of age, the target population for vaccination needs to be reexamined. Extending vaccination to all young children, to additional high-risk groups, and to pregnant women has potential to reduce the impact of influenza on children.

Influenza-related hospitalizations among children in Hong Kong

BACKGROUND

It has been difficult to define the burden of influenza in children because of confounding by the cocirculation of respiratory syncytial virus (RSV). In Hong Kong, China, the influenza and RSV infection seasons sometimes do not overlap, thus providing an opportunity to estimate the rate of influenza-related hospitalization in a defined population, free from the effects of RSV.

METHODS

In a retrospective, population-based study, we estimated the influenza-associated excess rate of hospitalization among children 15 years old or younger in the Hong Kong Special Administrative Region from 1997 to 1999. Data from a single hospital with intensive use of virologic analyses for diagnosis were obtained to define and adjust for underestimation of the model.

RESULTS

Peaks of influenza and RSV infection activity were well separated in 1998 and 1999 but overlapped in 1997. The adjusted rates of excess hospitalization for acute respiratory disease that were attributable to influenza were 278.5 and 288.2 per 10,000 children less than 1 year of age in 1998 and 1999, respectively; 218.4 and 209.3 per 10,000 children 1 to less than 2 years of age; 125.6 and 77.3 per 10,000 children 2 to less than 5 years of age; 57.3 and 20.9 per 10,000 children 5 to less than 10 years of age; and 16.4 and 8.1 per 10,000 children 10 to 15 years of age.

CONCLUSIONS

In the subtropics, influenza is an important cause of hospitalization among children, with rates exceeding those reported for temperate regions.

Pharmacokinetics and dosage recommendations for an oseltamivir oral suspension for the treatment of influenza in children

OBJECTIVE

Oseltamivir (Ro 64-0796) is an ester prodrug of the active metabolite Ro 64-0802 (oseltamivir carboxylate), a potent and selective inhibitor of the neuraminidase enzyme of influenza virus. In this study we report the pharmacokinetics of oseltamivir in healthy children volunteers (study 1) and in children with influenza (study 2).

STUDY PARTICIPANTS AND METHODS

In study 1, an open-label, single dose study, serial plasma samples were obtained from a total of 18 healthy children (5 to 18 years) who were grouped by age (n = 6 per group) and received single oral doses of oseltamivir 2 mg/kg. In study 2, a randomised, placebo controlled phase III study in paediatric children (1 to 12 years) presenting with influenza symptoms, 199 pharmacokinetic sparse samples were obtained from 87 patients, and serial samples were obtained from 5 patients. Pooled data were compared with those from adult studies.

RESULTS

Children (1 to 12 years) eliminated the active metabolite faster than both adolescents (13 to 18 years) and adults, resulting in lower exposure to the active drug. In these children, oseltamivir 2 mg/kg twice daily resulted in drug exposures within the range associated with tolerability and efficacy in adults administered approximately 1 mg/kg twice daily. Unit doses of oseltamivir 30, 45 and 60mg oral suspension are recommended twice daily in children weighing < or =15 kg (or < or =33 lb, aged 1 to 3 years), > 15 to 23 kg (or >33 to 51 lb, aged 4 to 7 years) and >23 to 40 kg (or >51 to 88 lb, aged 8 to 12 years), respectively. A 75 mg capsule may be a viable dosage formulation in children (e.g. over 8 years of age) who are able to swallow solid dosage forms.

CONCLUSIONS

Young children cleared the active metabolite oseltamivir carboxylate at a faster rate than older children and adults. Convenient administration recommendations for the oseltamivir oral suspension in children are possible to maintain drug exposure within the target window.