Antiviral treatment of influenza in children

Influenza Antiviral Treatment and Length of Stay

BACKGROUND

Antiviral treatment is recommended for hospitalized patients with suspected and confirmed influenza, but evidence is limited among children. We evaluated the effect of antiviral treatment on hospital length of stay (LOS) among children hospitalized with influenza.

METHODS

We included children <18 years hospitalized with laboratory-confirmed influenza in the US Influenza Hospitalization Surveillance Network. We collected data for 2 cohorts: 1 with underlying medical conditions not admitted to the ICU (n = 309, 2012-2013) and an ICU cohort (including children with and without underlying conditions; n = 299, 2010-2011 to 2012-2013). We used a Cox model with antiviral receipt as a time-dependent variable to estimate hazard of discharge and a Kaplan-Meier survival analysis to determine LOS.

RESULTS

Compared with those not receiving antiviral agents, LOS was shorter for those treated ≤2 days after illness onset in both the medical conditions (adjusted hazard ratio: 1.37, P = .02) and ICU (adjusted hazard ratio: 1.46, P = .007) cohorts, corresponding to 37% and 46% increases in daily discharge probability, respectively. Treatment ≥3 days after illness onset had no significant effect in either cohort. In the medical conditions cohort, median LOS was 3 days for those not treated versus 2 days for those treated ≤2 days after symptom onset (P = .005).

CONCLUSIONS

Early antiviral treatment was associated with significantly shorter hospitalizations in children with laboratory-confirmed influenza and high-risk medical conditions or children treated in the ICU. These results support Centers for Disease Control and Prevention recommendations for prompt empiric antiviral treatment in hospitalized patients with suspected or confirmed influenza.

Early Administration of Oseltamivir Within 48 Hours After Onset of Flulike Symptoms Can Reduce the Risk of Influenza B Virus-Associated Pneumonia in Hospitalized Pediatric Patients with Influenza B Virus Infection

We conducted a retrospective study to identify the risk factors for pneumonia in hospitalized pediatric patients with influenza B infection. Receiving oseltamivir within the first 48 hours of onset and frequent cough was respectively considered as a protective factor and a risk factor for the influenza B virus-associated pneumonia in hospitalized pediatric patients. Early administration of oseltamivir can reduce the risk of influenza B virus-associated pneumonia.

Risk factors for influenza B virus-associated pneumonia in adults

BACKGROUND

There is limited knowledge regarding the risk factors for influenza B virus-associated pneumonia in adults. This study aimed to determine the risk factors for influenza B virus-associated pneumonia in adults.

METHODS

We used viral surveillance data during the pandemic season between November 2017 and April 2018 from the University of Hong Kong-Shenzhen Hospital medical record database. The files of patients ages 18 years or older were reviewed for demographics, clinical characteristics, laboratory findings, and outcome. Multivariate logistic regression analysis was performed to identify risk factors associated with influenza B virus-associated pneumonia.

RESULTS

A total of 78 patients with influenza B, ages 20 to 87 years, were identified. Comparing cases with pneumonia vs cases without pneumonia, there were significant differences in the following: age in years (67.41 ± 16.63 vs 58.16 ± 17.65; P = .028), age group (74.1% vs 51.0%; P = .049), chronic respiratory diseases (70.4% vs 21.6%; P = .000), shortness of breath (40.7% vs13.7%; P = .007), abnormal breath sounds on auscultation (51.9% vs 21.6%; P = .006), and serum alanine transaminase level (30.07 ± 10.73 vs 38.64 ± 21.68; P = .022). Logistic regression models indicated that chronic respiratory diseases (odds ratio, 8.452; 95% confidence interval, 2.768-25.808; P = .000) and shortness of breath (odds ratio, 1.261; 95% confidence interval, 1.015-1.566; P = .036) were independent risk factors.

CONCLUSIONS

This study suggests that chronic respiratory diseases and shortness of breath are independent risk factors for influenza B virus-associated pneumonia in adult patients.

Oseltamivir for influenza infection in children: risks and benefits

Influenza is a common disease affecting many children each year. In a number of cases, particularly in children <2 years old and in those with severe chronic underlying disease, influenza can be complicated by lower respiratory tract infections, acute otitis media, rhinosinusitis, febrile seizures, dehydration or encephalopathy. Oseltamivir is the influenza virus drug that is most commonly studied in children for both the treatment and prevention of influenza. To avoid the risk that children with mild influenza or patients suffering from different viral infections receive oseltamivir, oseltamivir treatment should be recommended only in severe influenza cases, especially if confirmed by reliable laboratory tests. However, therapy must be initiated considering the risk of complications and the presence of severe clinical manifestations at age- and weight-appropriate doses. Because the vaccine remains the best option for preventing influenza and its complications, prophylaxis using oseltamivir should only be considered in select patients.

Influenza B virus-associated pneumonia in pediatric patients: clinical features, laboratory data, and chest X-ray findings

BACKGROUND

The clinical significance of influenza B is frequently overlooked, and reports on influenza B pneumonia in children are limited. Therefore, the clinical features of associated complications have rarely been reported. The aim of this study is to evaluate the clinical characteristics in pediatric patients with influenza B virus-associated pneumonia.

METHODS

From January 2009 to February 2012, 389 consecutive patients under 18 years old with influenza B virus infection were enrolled into the study. Thirty-four patients were defined as the pneumonia group by clinical symptoms and chest X-ray (CXR) findings, and 90 patients who had laboratory data and normal CXR findings were recruited to form the nonpneumonia group.

RESULTS

The age of the patients in the pneumonia group was significantly younger (median of 5.3 vs. 6.6 years). The white blood cell count (median of 7.5 vs. 5.7 × 10(9) cells/L) and C-reactive protein level (median of 21.1 vs. 5.7 mg/L) were higher, but the hemoglobin level was lower (median of 12.6 vs. 13.2 g/dL) in the pneumonia group. The CXR findings revealed that 29.4% of patients had alveolar consolidation, 32.4% had interstitial infiltration, and 38.2% had ground glass opacity. Two of four patients with pleural effusion had a positive bacteria culture, and both of them died.

CONCLUSION

Pneumonia should be considered in pediatric patients with influenza B virus infection presenting with younger age, higher white blood cell count, lower hemoglobin, and higher C-reactive protein level. The CXR findings were varied. Patients with pleural effusion and positive bacterial culture may have more severity of clinical outcome.

H1N1 pandemic: clinical and epidemiologic characteristics of the Canadian pediatric outbreak

Canada was one of the first countries affected by the 2009 influenza H1N1 pandemic with two waves - one from May to June and one from October to December. The 2009 influenza H1N1 pandemic had many unique features when compared with seasonal influenza, including the following: more than half of the affected people were children; asthma was the most significant risk factor for hospital admission; and Aboriginal and pregnant women had a higher risk of hospital admission and complications. Antiviral therapy was widely used but data did not show any effect on the pediatric population. Outbreak spread was possibly promoted from child-child and child-adult contact, and therefore the vaccination campaign targeted the pediatric population and achieved good coverage among young children (57%). Vaccination efficacy was difficult to test because of the vaccination delay. Improvement in models of prevention and treatment are urgently needed to prepare for the possible future pandemics.

Neuraminidase inhibitors for critically ill children with influenza

OBJECTIVE

Timely treatment with neuraminidase inhibitor (NAI) drugs appears to improve survival in adults hospitalized with influenza. We analyzed California surveillance data to determine whether NAI treatment improves survival in critically ill children with influenza.

METHODS

We analyzed data abstracted from medical records to characterize the outcomes of patients aged 0 to 17 years hospitalized in ICUs with laboratory-confirmed influenza from April 3, 2009, through September 30, 2012.

RESULTS

Seven hundred eighty-four influenza cases aged <18 years hospitalized in ICUs had information on treatment. Ninety percent (532 of 591) of cases during the 2009 H1N1 pandemic (April 3, 2009-August 31, 2010) received NAI treatment compared with 63% (121 of 193) of cases in the postpandemic period (September 1, 2010-September 30, 2012; P < .0001). Of 653 cases NAI-treated, 38 (6%) died compared with 11 (8%) of 131 untreated cases (odds ratio = 0.67, 95% confidence interval: 0.34-1.36). In a multivariate model that included receipt of mechanical ventilation and other factors associated with disease severity, the estimated risk of death was reduced in NAI-treated cases (odds ratio 0.36, 95% confidence interval: 0.16-0.83). Treatment within 48 hours of illness onset was significantly associated with survival (P = .04). Cases with NAI treatment initiated earlier in illness were less likely to die.

CONCLUSIONS

Prompt treatment with NAIs may improve survival of children critically ill with influenza. Recent decreased frequency of NAI treatment of influenza may be placing untreated critically ill children at an increased risk of death.

Influenza infection in infants aged <6 months during the H1N1-09 pandemic: a hospital-based case series

AIMS

To document risk factors, clinical features and outcomes in infants <6 months old admitted with laboratory-confirmed influenza to The Children's Hospital at Westmead during the H1N1-09 pandemic.

METHODS

Prospective, hospital-based case series of infants admitted June-September 2009, identified by the Paediatric Active Enhanced Disease Surveillance system and supplemented by telephone interview post-discharge.

RESULTS

Thirty-two infants <6 months old had influenza A: 18 H1N1-09, 11 H3N2 and three unknown subtypes. After discharge, 28 (88%) families were telephoned and provided additional information. Documented risk factors included close contact with young children (46%), living with a smoker (36%), intensive or special care at birth (25%), pre-existing illness (16%) and preterm birth (14%). The number of persons per household was double the state average. Only 14% of mothers were vaccinated against seasonal influenza. Infants commonly presented with cough (69%), coryza (69%), lethargy (38%), fever (31%), dyspnoea (31%) and vomiting (28%). Complications included pneumonia (22%), and bacterial (9%) and viral (6%) co-infection. Five infants (15%) required admission to intensive care, and one was mechanically ventilated. Sixteen (57%) had ongoing respiratory problems, and six (21%) presented to the Emergency Department within 6 months of discharge.

CONCLUSIONS

These novel data are clinically important. Rates of influenza in infants may be reduced by vaccinating close contacts and minimising exposure to infected contacts and cigarette smoke.

Guidance for clinical and public health laboratories testing for influenza virus antiviral drug susceptibility in Europe

Two classes of antiviral drugs are licensed in Europe for treatment and prophylaxis of influenza; the M2 ion-channel blockers amantadine and rimantadine acting against type A influenza viruses only and the neuraminidase enzyme inhibitors zanamivir and oseltamivir acting against type A and type B influenza viruses. This guidance document was developed for but not limited to the European Union (EU) and other European Economic Area (EEA) countries on how and when to test for influenza virus antiviral drug susceptibility. It is aimed at clinical and influenza surveillance laboratories carrying out antiviral drug susceptibility testing on influenza viruses from patients suspected of harbouring viruses with reduced susceptibility or for the monitoring of the emergence of such among circulating viruses, respectively. Therefore, the guidance should not be read as a directive or an algorithm for treatment. Monitoring for emergence of influenza viruses with reduced drug susceptibility in hospitalized cases is crucial for decision making on possible changes to antiviral treatment. Therefore, it is important to test for antiviral susceptibility in certain patient groups, such as patients treated with influenza antiviral drugs. It is also important to determine the frequency of viruses with natural (not related to drug use) reduced susceptibility among community and hospitalized cases, as this knowledge is essential for making empirical antiviral treatment decisions. Furthermore, testing of specimens from community influenza patients is needed to determine the frequency of viruses with reduced susceptibility and good viral fitness that are readily transmissible, as they may become dominant among circulating viruses. Phenotypic neuraminidase enzyme inhibition assays are recommended to determine the level of inhibition of the neuraminidase enzyme by antiviral drugs as a measure of drug susceptibility of the virus. Genotypic assays are recommended to identify amino acid substitutions in the neuraminidase and M2 ion-channel proteins that have been associated with reduced antiviral susceptibility previously. By 2012 all circulating seasonal influenza A(H1N1)pdm09 and A(H3N2) viruses were naturally resistant to the M2 ion-channel blockers, so priority should be given to testing for neuraminidase inhibitor susceptibility.

Estimating influenza incidence and rates of influenza-like illness in the outpatient setting

Please cite this paper as: Fowlkes et al. (2012) Estimating influenza incidence and rates of influenza‐like illness in the outpatient setting. Influenza and Other Respiratory Viruses DOI: 10.1111/irv.12014.

Background:  Estimating influenza incidence in outpatient settings is challenging. We used outpatient healthcare practice populations as a proxy to estimate community incidence of influenza‐like illness (ILI) and laboratory‐confirmed influenza‐associated ILI.

Methods:  From October 2009 to July 2010, 38 outpatient practices in seven jurisdictions conducted surveillance for ILI (fever with cough or sore throat for patients ≥2 years; fever with ≥1 respiratory symptom for patients <2 years). From a sample of patients with ILI, respiratory specimens were tested for influenza.

Results:  During the week of peak influenza activity (October 24, 2009), 13% of outpatient visits were for ILI and influenza was detected in 72% of specimens. For the 10‐month surveillance period, ILI and influenza‐associated ILI incidence were 20·0 (95% CI: 19·7, 20·4) and 8·7/1000 (95% CI: 8·2, 9·2) persons, respectively. Influenza‐associated ILI incidence was highest among children aged 2–17 years. Observed trends were highly correlated with national ILI and virologic surveillance.

Conclusions:  This is the first multistate surveillance system demonstrating the feasibility of using outpatient practices to estimate the incidence of medically attended influenza at the community level. Surveillance demonstrated the substantial burden of pandemic influenza in outpatient settings and especially in children aged 2–17 years. Observed trends were consistent with established syndromic and virologic systems.