Children with intellectual disability, cerebral palsy and other neurologic disorders are at much greater risk of complications from the flu, federal health officials said Wednesday.

In a study looking at the 2009 H1N1 flu outbreak, the U.S. Centers for Disease Control and Prevention found that a disproportionately high number of kids with neurologic disorders died as compared to other children. What’s more, of those conditions, the most frequently cited were intellectual disability, cerebral palsy and other neurodevelopmental disorders, researchers reported in the journal Pediatrics.

The 2009 flu season was significant because the number of children who perished during the pandemic that year was more than five times higher than the median for the previous five flu seasons.

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For the study, researchers reviewed data submitted to the CDC by state and local health agencies on influenza-related deaths in children. They found that 68 percent of the kids who died had an underlying medical condition. And of that group, the majority — 64 percent — had a neurologic disorder, researchers said.

“We’ve known for some time that certain neurologic conditions can put children at high risk for serious complications from influenza,” said Lyn Finelli, chief of the surveillance and outbreak response team in the CDC’s Influenza Division. “However, the high percentage of pediatric deaths associated with neurologic disorders that occurred during the 2009 H1N1 pandemic was a somber reminder of the harm that flu can cause to children with neurologic and neurodevelopmental disorders.”

In many cases, children with a neurologic disorder who died from the flu also had a coexisting condition like a pulmonary disorder, metabolic disorder, heart disease or a chromosomal abnormality, which exacerbated their risk, researchers said.

Pneumonia and acute respiratory distress syndrome were the most often reported complications among the children with disabilities who lost their lives.

Officials at the CDC say that kids with neurologic conditions have continued to be disproportionately impacted by the flu in the years since the H1N1 pandemic.

Data show that most of the children who died in 2009 were not vaccinated. The CDC is urging everyone over age 6 months to get an annual flu vaccine to mitigate risk for the illness.