WASHINGTON (AP) — This year’s flu season has proven to be challenging, noted as the most severe in 15 years. Federal health authorities are now investigating whether this uptick has resulted in an increase of rare but serious brain complications in children.

According to the Centers for Disease Control and Prevention (CDC), approximately 19,000 flu-related deaths have occurred this winter, with 86 of those being children. On Thursday, the CDC revealed that at least nine of these children suffered from brain complications, prompting a request to state health departments for assistance in assessing additional cases.

However, there is some positive news: the CDC also indicated that this year’s flu vaccine effectively reduces the risk of hospitalization due to the flu for those who have received it — a group that makes up 45% of Americans. This report comes just a day after the Trump administration disrupted the proceedings of health agencies by canceling a pivotal meeting of experts tasked with recommending the composition of next winter’s flu vaccine.

It’s still not too late to get vaccinated this flu season. “If you haven’t had your flu shot yet, now is the time to do so, as flu activity remains high across the majority of the country,” advised Dr. Sean O’Leary from the American Academy of Pediatrics.

The efficacy of flu shots can vary each year. Although the vaccine may not be highly effective at preventing all infections, its primary purpose is to “prevent hospitalization and keep you safe,” explained Dr. William Schaffner, a vaccine expert from Vanderbilt University.

Initial CDC data released on Thursday found that children vaccinated this season were 64% to 78% less likely to be hospitalized compared to unvaccinated children, while adults were 41% to 55% less likely to face hospitalization.

Regarding the concerning brain complications, health authorities have alerted doctors to monitor flu-affected children for symptoms such as seizures and hallucinations, indicative of “influenza-associated encephalopathy or encephalitis,” with a more severe form known as “acute necrotizing encephalopathy.” Encephalitis refers to inflammation of the brain.

On Thursday, the CDC conducted an analysis of 1,840 flu-related child deaths since 2010, revealing that 166 were associated with neurological complications, the majority of which were among unvaccinated individuals. However, the agency remains uncertain if the nine fatalities reported this year, four of which involved the more severe subtype, represent an upward trend.

The lack of regular tracking for these neurological issues complicates efforts to find clear answers. Dr. Keith Van Haren of Stanford Medicine Children’s Health indicated earlier this month that he had heard of around 15 flu-related cases of the severe subtype from colleagues nationwide, noting that there may be additional cases fitting the criteria, though details on fatalities were not provided.

Dr. O’Leary reassured parents that such complications are rare, emphasizing the importance of seeking medical attention if a child exhibits unusual or troubling symptoms during a flu illness, such as difficulty breathing.

Neurological issues tend to occur more frequently during severe flu seasons, potentially linked to specific influenza strains, and survivors may experience ongoing complications, including seizures, according to Dr. O’Leary.

Meanwhile, vaccine manufacturers have already begun preparations for the lengthy process of developing next winter’s flu vaccines. A meeting of the Food and Drug Administration (FDA) advisory committee was originally scheduled for March 13 to discuss which strains to incorporate but was canceled, leaving uncertainty about the government’s next steps.

“We have always strived for transparency regarding vaccine discussions,” remarked O’Leary, stressing the necessity for the public to understand the considerations involved in determining flu vaccine formulations and broader vaccination guidelines.

According to Andrew Nixon, communications director for the Department of Health and Human Services, “The FDA will publicly release its recommendations for manufacturers in time for updated vaccines to be available for the 2025-2026 influenza season.”

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Contributions to this report were made by AP reporters JoNel Aleccia and Mike Stobbe.

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The Associated Press Health and Science Department is supported by the Howard Hughes Medical Institute’s Science and Educational Media Group. The AP is solely accountable for all content presented.