Reports of Encephalopathy Among Children with Influenza-Associated Mortality - United States, 2010-11 Through 2024-25...

Area of Science:

• Pediatric Neurology
• Infectious Diseases
• Public Health Surveillance

Background:

• Anecdotal reports of severe influenza-associated acute necrotizing encephalopathy (ANE) in children emerged in early 2025.
• Influenza-associated encephalopathy or encephalitis (IAE) is a serious complication of influenza infection in pediatric populations.
• Existing surveillance systems may not fully capture the incidence of IAE and ANE.

Purpose of the Study:

• To examine trends in influenza-associated encephalopathy or encephalitis (IAE) among pediatric deaths.
• To analyze the demographic and clinical characteristics of children with fatal IAE.
• To inform healthcare providers about the recognition and management of IAE/ANE.

Main Methods:

• Analysis of pediatric influenza-associated deaths from the 2010-11 through 2024-25 influenza seasons.
• Review of case data for the presence of influenza-associated encephalopathy or encephalitis (IAE).
• Contacting state health departments for specific case ascertainment, including ANE diagnoses.

Main Results:

• IAE was identified in 9% (166/1840) of pediatric influenza-associated deaths across seasons (2010-11 to 2024-25).
• Preliminary 2024-25 data show 13% (9/68) of pediatric influenza deaths had IAE.
• Patients with fatal IAE were median 6 years old, 54% had no underlying conditions, and 20% were vaccinated.

Conclusions:

• Influenza-associated encephalopathy or encephalitis (IAE) represents a significant proportion of pediatric influenza deaths.
• Healthcare providers should maintain a high index of suspicion for IAE in children with acute febrile illness and neurological symptoms.
• Prompt diagnosis, influenza testing, neuroimaging, antiviral therapy, and supportive care are critical. Annual influenza vaccination is recommended.