Brain damage reported in 13% of kids who have died of flu this season, CDC finds

Roughly 1 in 8 child flu deaths in the U.S. so far this year have been linked to brain damage, according to a report released by the Centers for Disease Control and Prevention (CDC).

The U.S. is experiencing its most severe flu season in more than a decade, Live Science previously reported. More than 19,000 people have died including 68 children, at least nine of whom had flu-associated brain complications, according to a CDC Morbidity and Mortality Weekly Report published on Feb. 27.

In January, the CDC received anecdotal reports of children becoming critically ill and dying with influenza-associated encephalopathy or encephalitis (IAE), a spectrum of neurological syndromes. Encephalopathy is a group of conditions that cause brain dysfunction while encephalitis causes brain swelling, according to the Cleveland Clinic. IAE symptoms include seizures, decreased level of consciousness, hallucinations and personality changes lasting more than 24 hours, according to the report.

The CDC doesn't normally track cases of IAE, so it's not clear whether the number of cases reported this season is higher than in previous years. However, they did warn doctors to be on the lookout for IAE.

"It is not known whether cases observed in the 2024–25 season vary from expected numbers," the CDC report authors wrote. "Clinicians should consider IAE in children with influenza and abnormal neurologic signs or symptoms."

Related: How do people die of the flu?

Flu is among the deadliest viruses in the world. While it kills around 1.8 people per 100,000 infections, flu infects enough people that thousands die from it every year in the U.S. Nervous system injury, including IAE, is one of the main causes of flu fatalities among children, according to a 2021 study published in the journal Medical Science Monitor.

To investigate anecdotal reports of IAE, the CDC contacted state health departments for data on influenza-associated deaths in children across flu seasons between 2010 and 2025. Flu can spread all year round, but there are more cases in the fall and winter (the flu season), with activity peaking between December and February, according to the CDC.

The CDC found that as of Feb. 8 in the 2024-2025 season, 68 children had died with flu, with IAE documented in nine (13%) of those cases. That compares to a rate of 9% across all years, but it varied season to season and peaked at 14% in the 2011-2012 season, according to the report.

While the CDC couldn't identify whether the current rate of IAE was abnormal, the report highlighted the importance of vaccination and recommended flu shots for all eligible people aged 6 months or older so long as influenza viruses are circulating.

"Influenza vaccination is an important tool for preventing influenza and its associated complications," the report authors wrote.

Flu vaccine uncertainty

Early data suggest that this year's flu shots have dramatically reduced seasonal flu hospitalizations. However, uncertainty hangs over the next vaccination round for the 2025-2026 season.

Flu mutates quickly. So every year, manufacturers use strains circulating in the Southern Hemisphere to predict the strains most likely to circulate in the coming season and create updated versions of the flu vaccine targeted to those strains. A U.S. Food and Drug Administration (FDA) advisory panel normally meets around this time of year to decide which strains should be included in the vaccines for the next season. That meeting was scheduled for Mar. 13 but was canceled without reason, Reuters reported on Feb. 28.

There is concern among experts that the cancellation could disrupt the production of flu vaccines, which could mean higher rates of serious illness and death, Live Science previously reported.

An FDA spokesperson told Reuters on Feb. 28 that it would make recommendations to manufacturers public in time for updated vaccines to be available for the 2025-2026 season.

This is the second time a vaccine advisory panel has been disrupted since Robert F. Kennedy Jr. took over as head of the U.S. Department of Health and Human Services, Reuters reported. Kennedy Jr. is a notable vaccine skeptic, though he's denied being anti-vaccine.