Antiviral Use in Canadian Children Hospitalized for Influenza

Recommendations for Prevention and Control of Influenza in Children, 2024-2025: Technical Report

This technical report accompanies the recommendations of the American Academy of Pediatrics for the routine use of influenza vaccine and antiviral medications in the prevention and treatment of influenza in children during the 2024 to 2025 season. The rationale for the American Academy of Pediatrics recommendation for annual influenza vaccination of all children without medical contraindications starting at 6 months of age is provided. Influenza vaccination is an important strategy for protecting children and the broader community against influenza. This technical report summarizes recent influenza seasons, morbidity and mortality in children, vaccine effectiveness, and vaccination coverage and provides detailed guidance on vaccine storage, administration, and implementation. The report also provides a brief background on inactivated (nonlive) and live attenuated influenza vaccines, available vaccines for the 2024-2025 influenza season, vaccination during pregnancy and breastfeeding, diagnostic testing for influenza, and antiviral medications for treatment and chemoprophylaxis. Strategies to promote vaccine uptake are emphasized.

Antibiotic use in children hospitalised for influenza, 2010-2021: the Canadian Immunization Monitoring Program Active (IMPACT)

PURPOSE

To determine characteristics associated with inappropriate antibiotic use amongst children hospitalised for influenza.

METHODS

We performed active surveillance for laboratory-confirmed influenza hospitalizations amongst children ≤ 16 years old at the 12 Canadian Immunization Monitoring Program Active hospitals, from September 2010 to August 2021. Antibiotic use was presumed appropriate if any of the following indications were met: age < 1 month, immunocompromised, hemoglobinopathy, laboratory-confirmed bacterial infection, radiographically confirmed pneumonia, admission to an intensive care unit and mechanical ventilation. Regression analyses were used to identify baseline and clinical characteristics associated with antibiotic use amongst patients without an appropriate indication.

RESULTS

Amongst 8971 children, 6424 (71.6%) received any antibiotics during their hospitalisation. Amongst the 4429 children without an appropriate indication, 2366 (53.2%) received antibiotics. Antibiotic use amongst children without appropriate indication differed between study centres, ranging from 33.2% to 66.1% (interquartile range [IQR] 50.6-56.3%); it did not change significantly over time (p-value for trend = 0.28). In multivariable analyses, older age (adjusted odds ratio [aOR] 0.97, 95% confidence interval [CI] 0.96-0.99), presence of any high-risk condition (aOR 0.80, 95% CI 0.70-0.92), influenza virus type B (aOR 0.8, 95% CI 0.70-0.91) and croup (aOR 0.64, 95% CI 0.49-0.83) were associated with less, whilst fever ≥ 38.5 °C (aOR 1.82, 95% CI 1.42-2.35) and hospitalisation duration (aOR 1.12, 95% CI 1.09-1.15) were associated with more inappropriate antibiotic use.

CONCLUSIONS

Over two-third of children hospitalised for influenza received antibiotics, including over half of those without an appropriate indication for antibiotic treatment. Differences amongst study centres suggest the importance of contextual determinants of antibiotic use.

Bloodstream Infections in Children Hospitalized for Influenza, the Canadian Immunization Monitoring Program Active

BACKGROUND

We aimed to estimate the proportion of children hospitalized for influenza whose illness was complicated by bloodstream infection, describe their clinical course, and identify the factors associated with bloodstream infection.

METHODS

We performed active surveillance for laboratory-confirmed influenza hospitalizations among children ≤16 years old at the 12 Canadian Immunization Monitoring Program Active hospitals, from the 2010-2011 to 2020-2021 influenza seasons. Factors associated with bloodstream infection were identified using multivariable logistic regression analyses.

RESULTS

Among 9179 laboratory-confirmed influenza hospital admissions, bloodstream infection occurred in 87 children (0.9%). Streptococcus pyogenes (22%), Staphylococcus aureus (18%) and Streptococcus pneumoniae (17%) were the most common bloodstream infection pathogens identified. Children with cancer [adjusted odds ratio (aOR): 2.78; 95% confidence interval (CI): 1.23-5.63], a laboratory-confirmed nonbloodstream bacterial infection (aOR: 14.1; 95% CI: 8.04-24.3) or radiographically-confirmed pneumonia (aOR: 1.87; 95% CI: 1.17-2.97) were more likely to experience a bloodstream infection, whereas children with chronic lung disorders were less likely (aOR: 0.41; 95% CI: 0.19-0.80). Disease severity markers such as intensive care unit admission (aOR: 2.11; 95% CI: 1.27-3.46), mechanical ventilation (aOR: 2.84; 95% CI: 1.63-4.80) and longer hospital length of stay (aOR: 1.02; 95% CI: 1.01-1.03) were associated with bloodstream infection. Bloodstream infection also increased the odds of death (aOR: 13.0; 95% CI: 4.84-29.1) after adjustment for age, influenza virus type and the presence of any at-risk chronic condition.

CONCLUSIONS

Bloodstream infections, although infrequent, are associated with intensive care unit admission, mechanical ventilation, increased hospital length of stay and in-hospital mortality, thus requiring increased levels of care among pediatric influenza hospitalizations.

Recommendations for Prevention and Control of Influenza in Children, 2023-2024

This technical report accompanies the recommendations of the American Academy of Pediatrics for the routine use of influenza vaccine and antiviral medications in the prevention and treatment of influenza in children during the 2023-2024 season. The rationale for the American Academy of Pediatrics recommendation for annual influenza vaccination of all children without medical contraindications starting at 6 months of age is provided. Influenza vaccination is an important strategy for protecting children and the broader community against influenza. This technical report summarizes recent influenza seasons, morbidity and mortality in children, vaccine effectiveness, and vaccination coverage, and provides detailed guidance on vaccine storage, administration, and implementation. The report also provides a brief background on inactivated and live-attenuated influenza vaccines, available vaccines this season, vaccination during pregnancy and breastfeeding, diagnostic testing for influenza, and antiviral medications for treatment and chemoprophylaxis. Strategies to promote vaccine uptake are emphasized.

Outcomes of immunocompromised children hospitalized for influenza, 2010-2021, the Canadian Immunization Monitoring program active (IMPACT)

OBJECTIVES

To evaluate immunocompromising conditions and subgroups of immunocompromise as risk factors for severe outcomes among children admitted for influenza.

METHODS

We performed active surveillance for laboratory-confirmed influenza hospitalizations among children ≤16 years old at the 12 Canadian Immunization Monitoring Program Active hospitals, during 2010-2021. Logistic regression analyses were used to compare outcomes between immunocompromised and non-immunocompromised children, and for different subgroups of immunocompromise. The primary outcome was intensive care unit (ICU) admission; secondary outcomes were mechanical ventilation and death.

RESULTS

Among 8982 children, 892 (9.9%) were immunocompromised; these patients were older (median 5.6 [IQR 3.1 - 10.0] vs 2.4 [1 -6] years, p<0.001) than non-immunocompromised children, had similar frequency of comorbidities excluding immunocompromise and/or malignancy (38% [340/892) vs 40% [3272/8090], p=0.2), but fewer respiratory symptoms, such as respiratory distress (20% [177/892] vs 42% [3424/8090], p<0.001). In multivariable analyses, immunocompromise (adjusted odds ratio [aOR] 0.19, 95% CI 0.14-0.25) and its subcategories immunodeficiency (aOR 0.16, 95% CI 0.10-0.23), immunosuppression (aOR 0.17, 95% CI 0.12-0.23), chemotherapy (aOR 0.07, 95% CI 0.03-0.13) and solid organ transplantation (aOR 0.17, 95% CI 0.06-0.37) were associated with decreased probability of ICU admission in children admitted for influenza. Immunocompromise was also associated with decreased probability for mechanical ventilation (aOR 0.26, 95% CI 0.16-0.38) or death (aOR 0.22, 95% CI 0.03-0.72).

CONCLUSIONS

Immunocompromised children are overrepresented among hospitalizations for influenza, but have decreased probability of ICU admission, mechanical ventilation, and mortality following admission. Admission bias precludes generalizability beyond the hospital setting.

Trends and Changes in Influenza-associated Hospitalizations in Children During 25 Years in Finland, 1993-2018

BACKGROUND

Limited long-term data are available on potential changes in the demographics and management of children hospitalized with influenza.

METHODS

We identified all children ≤15 years old hospitalized with virologically confirmed influenza at Turku University Hospital, Finland, during the 25-year period of July 1993-June 2018. Data on clinical variables, comorbidities and management were retrieved directly from the medical records. Population-based rates of hospitalization were calculated using official annual databases of children living in the hospital catchment area.

RESULTS

Between 1993-1998 and 2013-2018, the median age of children increased from 1.3 years to 3.3 years ( P < 0.0001). The proportion of children <2 years of age decreased from 65.2% to 36.8%, whereas the proportion of children 6-15-year-old increased from 13.0% to 36.2% ( P < 0.0001 for both). The population-based rates of hospitalization decreased by 49% in children 1 year of age (incidence rate ratio, 0.51; 95% confidence interval: 0.27-0.92; P = 0.018) and increased by 194% in children 6-15 years old (incidence rate ratio, 2.94; 95% confidence interval: 1.70-5.32; P < 0.0001). The median duration of hospitalization shortened from 2.0 days (interquartile range [IQR], 1.0-4.0) to 1.0 day (IQR, 1.0-2.0; P < 0.0001).

CONCLUSIONS

During the 25 years, the median age of hospitalized children increased by 2 years, while the duration of hospitalization shortened.

Recommendations for Prevention and Control of Influenza in Children, 2022-2023

This technical report accompanies the recommendations of the American Academy of Pediatrics for the routine use of influenza vaccine and antiviral medications in the prevention and treatment of influenza in children during the 2022 to 2023 season. The American Academy of Pediatrics recommends annual influenza vaccination of all children without medical contraindications starting at 6 months of age. Influenza vaccination is an important strategy for protecting children and the broader community as well as reducing the overall burden of respiratory illnesses when other viruses, including severe acute respiratory syndrome-coronavirus 2, are cocirculating. This technical report summarizes recent influenza seasons, morbidity and mortality in children, vaccine effectiveness, and vaccination coverage, and provides detailed guidance on storage, administration, and implementation. The report also provides a brief background on inactivated and live attenuated influenza vaccine recommendations, vaccination during pregnancy and breastfeeding, diagnostic testing, and antiviral medications for treatment and chemoprophylaxis. Updated information is provided about the 2021 to 2022 influenza season, influenza immunization rates, the effectiveness of influenza vaccination on hospitalization and mortality, available vaccines, guidance for patients with history of severe allergic reactions to prior influenza vaccinations, and strategies to promote vaccine uptake.

Assessment of Temporal Patterns and Patient Factors Associated With Oseltamivir Administration in Children Hospitalized With Influenza, 2007-2020

IMPORTANCE

Oseltamivir therapy is recommended for all pediatric inpatients with influenza, particularly those with high-risk conditions, although data regarding its uptake and benefits are limited.

OBJECTIVE

To describe temporal patterns and independent patient factors associated with the use of oseltamivir and explore patterns in resource use and patient outcomes among children hospitalized with influenza.

DESIGN, SETTING, AND PARTICIPANTS

This multicenter retrospective cross-sectional study was conducted at 36 tertiary pediatric hospitals participating in the Pediatric Health Information System in the US. A total of 70 473 children younger than 18 years who were hospitalized with influenza between October 1, 2007, and March 31, 2020, were included.

EXPOSURES

Hospitalization with a diagnosis of influenza.

MAIN OUTCOMES AND MEASURES

The primary outcome was the use of oseltamivir, which was described by influenza season and by hospital. Patient factors associated with oseltamivir use were assessed using multivariable mixed-effects logistic regression models. Secondary outcomes were resource use (including antibiotic medications, chest radiography, supplemental oxygen, positive pressure ventilation, central venous catheter, and intensive care unit [ICU]) and patient outcomes (length of stay, late ICU transfer, 7-day hospital readmission, use of extracorporeal membrane oxygenation, and in-hospital mortality), which were described as percentages per influenza season.

RESULTS

Among 70 473 children hospitalized with influenza, the median (IQR) age was 3.65 (1.05-8.26) years; 30 750 patients (43.6%) were female, and 39 715 (56.4%) were male. Overall, 16 559 patients (23.5%) were Black, 36 184 (51.3%) were White, 14 133 (20.1%) were of other races (including 694 American Indian or Alaska Native [1.0%], 2216 Asian [3.0%], 372 Native Hawaiian or Pacific Islander [0.5%], and 10 850 other races [15.4%]), and 3597 (5.1%) were of unknown race. A total of 47 071 patients (66.8%) received oseltamivir, increasing from a low of 20.2% in the 2007-2008 influenza season to a high of 77.9% in the 2017-2018 season. Use by hospital ranged from 43.2% to 79.7% over the entire study period and from 56.5% to 90.1% in final influenza season studied (2019-2020). Factors associated with increased oseltamivir use included the presence of a complex chronic condition (odds ratio [OR], 1.42; 95% CI, 1.36-1.47), a history of asthma (OR, 1.31; 95% CI, 1.23-1.38), and early severe illness (OR, 1.19; 95% CI, 1.13-1.25). Children younger than 2 years (OR, 0.81; 95% CI, 0.77-0.85) and children aged 2 to 5 years (OR, 0.83; 95% CI, 0.79-0.88) had lower odds of receiving oseltamivir. From the beginning (2007-2008) to the end (2019-2020) of the study period, the use of antibiotic medications (from 74.4% to 60.1%) and chest radiography (from 59.2% to 51.7%) decreased, whereas the use of oxygen (from 33.6% to 29.3%), positive pressure ventilation (from 10.8% to 7.9%), and central venous catheters (from 2.5% to 1.0%) did not meaningfully change. Patient outcomes, including length of stay (median [IQR], 3 [2-5] days for all seasons), readmissions within 7 days (from 4.0% to 3.4%), use of extracorporeal membrane oxygenation (from 0.5% to 0.5%), and in-hospital mortality (from 1.1% to 0.8%), were stable from the beginning to the end of the study period.

CONCLUSIONS AND RELEVANCE

In this cross-sectional study of children hospitalized with influenza, the use of oseltamivir increased over time, particularly among patients with high-risk conditions, but with wide institutional variation. Patient outcomes remained largely unchanged. Further work is needed to evaluate the impact of oseltamivir therapy in this population.