We all know that influenza is a common and serious viral infection, but it’s good to be reminded ahead of the upcoming flu season, which typically starts in October.
There were an estimated 47 million to 82 million flu illnesses in the United States between October 2024 and May 2025, resulting in between 610,000 and 1.3 million hospitalizations, according to preliminary estimated ranges from the US Centers for Disease Control and Prevention.
Most fatalities occur in older individuals, but children can also die from the flu. The CDC estimates that flu-related deaths in children have generally ranged from 37 to 199 deaths each flu season.
Now, a new study in JAMA has examined a rare but severe complication that can occur in children who contract the flu. This complication, called acute necrotizing encephalopathy, or ANE, carries a mortality rate of 27% despite intensive care and treatment, according to the new research.
I wanted to learn more about complications associated with the flu, specifically about ANE, what researchers learned about children with ANE, and how can ANE be prevented. And what should parents and families know ahead of the next flu season?
To help with these questions, I spoke with CNN wellness expert Dr. Leana Wen. Wen is an emergency physician and clinical associate professor at George Washington University. She previously was Baltimore’s health commissioner.
CNN: What are complications associated with the flu? Who is most at risk?
Dr. Leana Wen: Most people who have the flu will recover without complications. They may go through days or even weeks having fever, runny nose, headache and fatigue, but these symptoms generally resolve without long-term consequences.
Some people, though, experience complications that could result in severe illness or even death. These complications include pneumonia, sinus and ear infections, brain and neurological conditions, and the worsening of existing medical problems such as heart and kidney disease.
People at higher risk for flu complications include individuals 65 years and older, children younger than 2 and pregnant women. In addition, there are a variety of chronic medical conditions that increase risk, including chronic lung disease, diabetes, heart disease, liver disorders, kidney dysfunction and any condition that makes you immunocompromised.
CNN: What exactly is ANE, and how common is it?
Wen: ANE is a rare but very serious condition that occurs as a result of influenza infection. It causes inflammation and swelling in the brain, and it can lead to seizures, impaired consciousness, coma, long-term brain damage and death.
It’s not known precisely how common this condition is or whether the incidence has been changing in recent years. It can also occur after other viral illnesses, but it has been most closely associated with influenza, and most often in children.
CNN: What did researchers in this study find out about children with ANE?
Wen: They sought information from US pediatric hospitals and public health agencies regarding cases of pediatric ANE treated between October 2023 and May 2025. In total, they included 41 children with influenza-related ANE.
The median age of these children was 5, and about 3 out of 4 were previously healthy. Importantly, just 16% of those for whom vaccination history was available had received the flu vaccine that season.
All these patients became very ill, and all developed encephalopathy, or altered brain function. Sixty-eight percent had seizures. Most had abnormalities in their platelet count, liver enzymes and spinal fluid composition.
Most patients received a combination of therapies, including steroids and immunoglobulins. Out of 41 patients in the analysis, 11 died. The median period between symptom onset and death was just three days; most of the children who died had such severe brain swelling that the pressure forced the brain downward, crushing vital areas that control breathing and heart function. All but one of the children who died had not received the latest flu vaccine. Among the survivors included in the analysis, 63% had at least moderate disability.
The first takeaway for me is that ANE, while rare, is extremely serious, with high morbidity and mortality. It can be deadly within a short period of time, which means prompt diagnosis and treatment are essential. Second, most children with ANE were previously healthy. Third, while some vaccinated children also became ill, most of those with ANE and nearly all of those who died had not received the flu vaccine that season.
CNN: How can ANE be prevented?
Wen: It is not known why most people who contract flu never develop ANE, but some do. It’s also not known whether there is anything that be done once someone contracts the flu to prevent ANE.
What is known is that getting the flu vaccine reduces the chance of contracting the flu and of becoming severely ill as a result. This JAMA study also suggests that vaccination reduces the likelihood of developing ANE and of dying from it. The article and an accompanying editorial emphasize the importance of everyone being up-to-date with the flu vaccine.
CNN: What else should parents and families know ahead of the next flu season?
Wen: Influenza is a common illness that can have serious complications, including in previously healthy individuals. Getting the flu vaccine is helpful both for reducing the chance of contracting the flu and for lowering the likelihood of developing complications. The CDC recommends the flu vaccine for virtually everyone 6 months and older. Parents should be sure that their children receive the flu vaccine in the fall and that they and others in the family are vaccinated, too.
Of course, flu is not the only contagious respiratory illness that can spread in fall and winter months. It’s important for people who have fever and active respiratory symptoms to stay away from others, especially those most vulnerable to severe illness. Good hand hygiene can lower the risk of spreading contagious diseases, as can taking precautions like masking in indoor crowded settings.
