WASHINGTON — This year’s harsh flu season – the most intense in 15 years – has federal health officials trying to understand if it sparked an increase in a rare but life-threatening brain complication in children.

The Centers for Disease Control and Prevention estimates 19,000 people have died from the flu so far this winter, including 86 children. Thursday, the CDC reported at least nine of those children experienced brain complications, and it has asked state health departments to help investigate if there are more such cases.

There is some good news: The CDC also reported that this year’s flu shots do a pretty good job preventing hospitalization from the flu — among the 45% of Americans who got vaccinated. But it comes a day after the Trump administration added to the uncertainty roiling government health agencies by canceling a meeting of experts who are supposed to help choose the recipe for next winter’s flu vaccine.

Still, it’s not too late to get vaccinated this year: “If you haven’t gotten your flu shot yet, get it because we’re still seeing high flu circulation in most of the country,” said Dr. Sean O’Leary of the American Academy of Pediatrics.

Flu shot effectiveness varies from year to year. While not great at blocking infections, the vaccine’s main role “is to keep you out of the hospital and to keep you alive,” said Vanderbilt University vaccine expert Dr. William Schaffner.

Preliminary CDC data released Thursday found children who got this year’s vaccine were between 64% and 78% less likely to be hospitalized than their unvaccinated counterparts, and adults were 41% to 55% less likely to be hospitalized.

What about those brain complications? Earlier this month, state health departments and hospitals warned doctors to watch for child flu patients with seizures, hallucinations or other signs of “influenza-associated encephalopathy or encephalitis” — and a more severe subtype called “acute necrotizing encephalopathy.” Encephalitis is brain inflammation.

Thursday, the CDC released an analysis of 1,840 child flu deaths since 2010, finding 166 with those neurologic complications. Most were unvaccinated. But the agency concluded it’s unclear if this year’s nine deaths with those complications — four of whom had the worse subtype — mark an uptick.

There’s no regular tracking of those neurologic complications, making it hard to find the answers. In California, Dr. Keith Van Haren of Stanford Medicine Children’s Health said earlier this month that he’d learned of about 15 flu-related cases of that severe subtype from doctors around the country and “we are aware or more cases that may also meet the criteria.” He did not say how many died.

O’Leary, with the pediatricians’ academy, said parents should remember this complication is rare — the advice remains to seek medical advice anytime a child with flu has unusual or concerning symptoms, such as labored breathing.

Doctors see more neurologic complications during severe flu seasons – they may be linked to particular influenza strains — and survivors can have ongoing seizures or other lingering problems, he said.

Meanwhile, vaccine makers already are gearing up for the months-long process of brewing next winter’s flu shots. A Food and Drug Administration advisory committee was supposed to meet on March 13 to help choose which flu strains to include but with that meeting’s cancellation, it’s unclear if the government will decide on its own.

“We have historically worked really hard to get transparency around all of these vaccine discussions,” said O’Leary, who said it’s important for the public to understand what goes into making decisions about the flu vaccine composition and other vaccine recommendations.