Low mortality and severe complications despite high influenza burden among Hong Kong children

Neurological involvement related to the influenza virus in children: A 5-year single-centre retrospective study

INTRODUCTION

Inflammation related to influenza virus infection can lead to multiple neurological presentations. Encephalitis is one of them, mostly accompanied by seizures, with different profiles depending on the epidemics and previous medical conditions.

MATERIALS AND METHODS

All children presenting neurological symptoms and positive for influenza virus RNA detection in a respiratory sample between November 2018 and April 2023, hospitalized in the Department of Paediatric Neurology of Toulouse Children's Hospital, were retrospectively analysed.

RESULTS

Among the 1,277 children diagnosed with influenza in our centre, 131 (10.3 %) were hospitalized for neurological features. The year 2020-2021 was marked by zero incidence of positive influenza tests, associated with the COVID-19 pandemic. Among the 131 patients included, 71.6 % were under 5 years old. Most of them (80.9 %) were infected by influenza A virus. The first neurological symptoms were mainly seizures in 73.3 % of patients. Possible or confirmed encephalitis was observed in 29 % of cases, including one acute necrotizing encephalopathy. Few children (6.1 %) presented with acute myositis. Twenty-seven patients (20.6 %) had a personal history of significant previous neurological disorders. Most patients (88.5 %) displayed a rapid favourable outcome, marked by the disappearance of their neurological symptoms within the first 2 days. Anti-epileptic drugs were introduced in 1.5 % of cases, and adapted in 16.8 %, mainly in patients with febrile status epilepticus and an abnormal EEG.

CONCLUSION

Neurological features were frequently associated with influenza infection in children; most were transient. Effects on long-term neurodevelopmental outcomes need to be clarified as our follow-up was limited, especially in children with pre-existing neurological conditions.

Clinical Spectrum and Burden of Influenza-Associated Neurological Complications in Hospitalised Paediatric Patients

BACKGROUND

Influenza is one of the most common causes of acute respiratory tract infections around the world. Influenza viruses can cause seasonal epidemics. There remains limited information on the impact of both seasonal influenza A and influenza B related hospitalisations from neurological complications in paediatric populations in Asia.

OBJECTIVES

To examine both the clinical spectrum and healthcare burden of influenza-associated neurological complications (IANCs) within the paediatric population of Hong Kong.

METHODS

We conducted a population-based retrospective study to identify all paediatric patients (<18 years) admitted to a public hospital in Hong Kong with a confirmed influenza A or B infection between 2014 and 2018 using the Clinical Data Analysis and Reporting System of the Hospital Authority. The clinical spectrum of the paediatric patients with IANCs was studied. The clinical burden of paediatric influenza patients with IANCs were compared to paediatric influenza patients without neurological complications.

RESULTS

A total of 28,016 children admitted to the paediatric wards diagnosed to have influenza A or B infection were identified, accounting for 5.7% (28,016/489,955) of total paediatric admissions. 67.3% had influenza A and 32.7% had influenza B, and 8.9% had IANCs. The mean annual incidence of IANCs in children was 57 per 100,000 population. The spectrum of IANCs in our paediatric patients included febrile seizures (80.6%), myositis (11.4%), seizures with fever (5.4%), influenza-associated encephalitis/encephalopathy (IAE) (2.6%) and rarely Guillain-Barré syndrome (0.04%). Most paediatric patients with IANCs (85.5%) presented at a young age of <6 years. Paediatric patients with IANCs had significant longer hospital stays (p < 0.001), higher percentages of mechanical ventilation use (p < 0.05) and PICU admissions (p < 0.001), and higher mortality rates (p < 0.001) compared to those without neurological complications. Amongst those with IANCs, IAE was the sole cause of all seven reported mortalities.

CONCLUSIONS

Seasonal influenza A & B is a common cause of hospitalisation for paediatric patients in Hong Kong. We found neurological complications from influenza A and B caused a significantly higher clinical burden compared to those without neurological complications. Children in younger age groups (<6 years old) are at highest risk and thus increasing vaccination coverage to this age group is recommended.

Mortality, length of stay, bloodstream and respiratory viral infections in a pediatric intensive care unit

OBJECTIVES

We investigated whether diagnostic categories and presence of infections were associated with increased mortality or length of stay (LOS) in patients admitted to a pediatric intensive care unit (PICU).

METHODS

A retrospective study of all PICU admissions between October 2002 and April 2016 was performed. Oncologic vs nononcologic, trauma/injuries vs nontraumatic, infectious (gram-positive, gram-negative, fungal bloodstream infections, common respiratory viruses) vs noninfectious diagnoses were evaluated for survival and LOS.

RESULTS

Pediatric intensive care unit admissions (n = 2211) were associated with a mortality of 5.3%. Backward binary logistic regression showed that nonsurvival was associated with leukemia (odds ratio [OR], 4.81; 95% confidence interval [CI], 2.2-10.10; P < .0005), lymphoma (OR, 21.34; 95% CI, 3.89-117.16; P < .0005), carditis/myocarditis (OR, 7.91; 95% CI, 1.98-31.54; P = .003), encephalitis (OR, 6.93; 95% CI, 3.27-14.67; P < .0005), bloodstream infections with gram-positive organisms (OR, 5.32; 95% CI, 2.67-10.60; P < .0005), gram-negative organisms (OR, 8.23; 95% CI, 4.10-16.53; P < .0005), fungi (OR, 3.93; 95% CI, 1.07-14.42; P = .039), and pneumococcal disease (OR, 3.26; 95% CI, 1.21-8.75; P = .019). Stepwise linear regression revealed that LOS of survivors was associated with bloodstream gram-positive infection (B = 98.2; 95% CI, 75.7-120.7; P < .0005).

CONCLUSIONS

Patients with diagnoses of leukemia, lymphoma, cardiomyopathy/myocarditits, encephalitis, and comorbidity of bloodstream infections and pneumococcal disease were significantly at risk of PICU mortality. Length of stay of survivors was associated with bloodstream gram-positive infection. The highest odds for death were among patients with leukemia/lymphoma and bloodstream coinfection. As early diagnosis of these childhood malignancies is desirable but not always possible, adequate and early antimicrobial coverage for gram-positive and gram-negative bacteria might be the only feasible option to reduce PICU mortality in these patients. In Hong Kong, a subtropical Asian city, none of the common respiratory viruses were associated with increased mortality or LOS in PICU.