Federal health officials say at least 16 more children died of the flu over the past week and more states are reporting high levels of illness. In a briefing Friday, the Centers for Disease Control and Prevention said the flu outbreak is responsible for at least 53 child deaths so far this season.

"Hospitalizations are now the highest we've seen," said CDC Acting Director Dr. Anne Schuchat, who called the flu one of the biggest health threats currently facing the U.S. She said the cumulative rate of hospitalizations for serious cases of flu is now even greater than in the previous high season of 2014-15. People age 65 and over have the highest rate of hospitalization for the flu.

One of every 14 visits to doctors and clinics were for symptoms of the flu. That's the highest level since the swine flu pandemic in 2009, the Associated Press noted.

High levels of flu-like illness were reported in 42 states, up from 39 states the previous week, and cases were geographically widespread across every state but Hawaii. 

In one sign of good news, Schuchat said the outbreak appears to be easing up in the West. But there are probably several weeks left of increasing flu activity this season, she warned.

"We aren't out of the woods yet, but there are steps everyone can take to fight the flu," Schuchat said.

She stressed that the CDC continues to recommend people get flu shots, even though the vaccine's effectiveness is lower than in some years. Canadian researchers reported Thursday that this year's flu vaccine is less than 20% effective against the most dominant strain of the virus. Schuchat said the vaccine still offers some protection and can reduce the severity of illness if you do get infected.

Schuchat, a 30-year veteran of the CDC, took over as acting director this week after Dr. Brenda Fitzgerald resigned amid controversy over financial conflicts of interest.

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