The CDC found brain damage in 13% of children who died from the flu. This image shows a healthy human brain under MRI. (Photo credit: Rajaaisya/Science Photo Library via Getty Images)
About one in eight childhood flu deaths in the United States this season was linked to brain damage, according to a report released by the Centers for Disease Control and Prevention (CDC).
As Live Science previously reported, the U.S. is experiencing its worst flu season in a decade. More than 19,000 people have died from the flu, including 68 children, at least nine of whom have had flu-related brain complications, according to the CDC's Morbidity and Mortality Weekly Report released on Feb. 27.
In January, the CDC received isolated reports of children who became seriously ill and died from influenza-associated encephalopathy or encephalitis (IAE), a group of neurological syndromes. Encephalopathy refers to conditions that cause brain dysfunction, while encephalitis results in swelling of the brain, according to the Cleveland Clinic. Symptoms of IAE include seizures, decreased level of consciousness, hallucinations, and personality changes that last more than 24 hours, the report said.
The CDC does not typically keep track of IAE cases, so it is unclear whether the number of reported cases this season is higher than in previous years. However, they cautioned doctors to be alert for IAE.
“It is unknown whether cases reported in the 2024–25 season differ from expected values,” the CDC report authors wrote. “Clinicians should consider IAE in children with influenza and abnormal neurologic signs or symptoms.”
Influenza is considered one of the deadliest viruses in the world. Although it kills about 1.8 people per 100,000 infections, the flu affects so many people that it kills thousands in the United States each year. Nervous system involvement, including IAE, is one of the leading causes of flu-related deaths in children, according to a 2021 study published in the journal Medical Science Monitor.
To examine individual IAE case reports, CDC asked state health departments for data on childhood influenza deaths during the 2010 through 2025 seasons. Influenza can occur throughout the year, but the greatest number of cases occurs in the fall and winter (flu season), with peak activity from December through February, according to the CDC.
The CDC found that as of Feb. 8, 68 children had died from influenza during the 2024-25 flu season, with nine (13%) of those deaths resulting from IAE. That compares with 9% in previous years, but has varied by season and reached 14% in the 2011-2012 season, according to the report.
While the CDC could not determine whether the current level of flu cases is abnormal, the report emphasizes the importance of vaccination and recommends that all eligible people 6 months of age and older receive flu shots while flu viruses are circulating.
“Influenza vaccination is an important means of preventing influenza and its complications,” the report's authors note.
Flu Vaccine Uncertainty
Early data show that flu vaccinations have significantly reduced hospitalizations due to seasonal flu this season. However, uncertainty remains about the next round of vaccinations for the 2025-2026 season.
Flu mutates quickly. So every year, manufacturers use strains circulating in the Southern Hemisphere to predict which strains are likely to emerge the following season and develop updated versions of the vaccine that target those strains. An advisory panel to the U.S. Food and Drug Administration (FDA) typically meets around this time of year to determine which strains should be included in vaccines for the next season. That meeting was scheduled for March 13 but was canceled.
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