Almost 300 kids died during the last flu season - they need their shots this year
The reports, published yesterday in Morbidity and
Mortality Weekly Report (MMWR), include data on the 280 US children
who died during the 2024-25 flu season, along with information on 109 children
who died from a rare and severe neurologic complication of flu during the
season. The 280 pediatric flu deaths are the highest number reported in the
United States since the 2009-10 H1N1 pandemic and the highest for a
non-pandemic flu season since child deaths became nationally notifiable in
2004.
The reports add further information on what the CDC has
previously described as a high-severity flu season.
Highest mortality rate seen in infants
In first report, researchers with the
CDC's National Center for Immunization and Respiratory Diseases analyzed data
from the Influenza-Associated Pediatric Mortality Surveillance System, which
collects reports on pediatric flu deaths from state and local health departments.
The analysis includes information on flu virus types, underlying medical
conditions, vaccination status, and healthcare use during illness.
The 280 children who died with flu from September 29, 2024
to September 13, 2025, represent a national rate of 3.8 deaths per 1 million
children. The median age at time of death was 7 years, and 61% of deaths
occurred in children under the age of 9 years. The influenza-associated
mortality rate was highest overall in infants under 6 months of age (11.1 per 1
million), higher among girls (4.5) than boys (3.1). Among racial and ethnic
groups, Black children (5.8) had the highest mortality rate.
Influenza A viruses were associated with 240 deaths (86%) and influenza B viruses with 38 (14%). Of the 169 influenza A deaths with a known subtype, 95 (56%) were A(H1N1)pdm09 viruses, 73 (43%) were A(H3N2) viruses, and one (less than 1%) had both A(H1N1)pdm09 and A(H3N2) detected.
Among the 262 children with available medical histories, 148
(56%) had at least one reported underlying medical condition, with neurologic
conditions the most frequently reported (93; 63%). Among the 218 children with
available data on clinical complications before death, the most common
complication was sepsis (108; 50%), followed by pneumonia (82; 38%), acute
respiratory distress syndrome (60; 28%), seizures (53; 24%), and encephalopathy
or encephalitis (40; 18%).
Overall, 112 (40%) of children were treated with flu
antiviral medications, most commonly oseltamivir (104; 93%). Roughly half of
the children who died had not been admitted to the hospital at the time of
their death, with 61 (22%) deaths occurring outside of the hospital and 74
(27%) in the emergency department.
Of the 208 children with vaccine information available, 89%
had not been fully vaccinated against flu.
The authors of the report say that while it's unclear why
there were more pediatric deaths in the 2024-25 flu season than previous
seasons, the best way to protect children from flu, particularly those with
underlying conditions, is to get them vaccinated.
"All persons aged ≥6 months who do not have
contraindications should receive an annual influenza vaccination to prevent
influenza and its complications, including influenza-associated death,"
they wrote.
Influenza-associated encephalopathy
In the other MMWR report,
researchers with the CDC and state and local health departments analyzed case
reports on deaths among children from a severe and deadly form of
influenza-associated encephalopathy (IAE) called acute necrotizing
encephalopathy (ANE), which occurs when a virus (most commonly flu) triggers an
immune response that leads to brain swelling, bleeding, and tissue death.
Children who survive ANE can experience lasting effects,
including developmental delays, cognitive or behavioral challenges, and
difficulty with movement or coordination.
Although there's no surveillance system in the United States
for flu-related neurologic complications, the CDC requested the reports in
January, after it was alerted to several deaths of children with
influenza-associated ANE. Of the 192 reports that met CDC criteria, 109 were
categorized as IAE, 37 (34%) of which were subcategorized as ANE.
Among the 109 patients with IAE, the median patient age was
5 years, 97 (89%) had influenza A, and 58 (55%) of 106 children with medical
histories had no underlying medical conditions. Neurologic symptoms commenced a
median of 2 days after illness onset. Of all IAE patients, 80 (74%) were
admitted to the intensive care unit (ICU), 59 (54%) received mechanical
ventilation, and 21 (19%) died.
Among the 37 ANE patients, the median patient age was 4
years, 34 (92%) had influenza A, and 18 (51%) of 35 children with available
medical histories had no underlying conditions. All ANE patients were admitted
to the ICU, 33 (89%) received mechanical ventilation, and 15 (41%) died.
Only 15 (16%) IAE and 4 (13%) ANE patients had received one
or more doses of the 2024-25 flu vaccine more than 2 weeks before illness
onset, while 86 (84%) of IAE and 31 (94%) of ANE patients received a flu
antiviral.
The study authors say the findings are a reminder for
parents and healthcare providers that all children are at risk for severe
neurologic complications from flu.
"During influenza season, parents and caregivers of
children with neurologic signs and symptoms (e.g., seizures, hallucinations, or
altered level of consciousness) in conjunction with fever or respiratory
symptoms should seek care urgently," they wrote. "Health care
providers should consider IAE in children with recent or current febrile
illness with encephalopathy, monitor these children for clinical deterioration,
and initiate appropriate supportive care."
