The outbreak has reached nearly every corner of the country, with every state except Hawaii and OR reporting widespread flu, Schuchat said. "Flu is incredibly hard to predict, and we don't know if we've hit a peak". How well it is working the USA won't be known until next week.
One of the worst flu outbreaks in the United States in almost a decade worsened last week and will likely linger for several weeks, causing more deaths, the Centers for Disease Control and Prevention said on Friday.
She urged sick people to stay home and said it is still not too late for people to get a flu vaccine, which offers some protection.
"The tragic death of a child due to the flu is a reminder of the devastating effects this illness can have on people of all ages", the New York City Health Department said in a statement to ABC News. A quarter of the hospital's emergency department visits are patients with flu, and the hospital has added nursing staff and placed beds in halls to accommodate the increase, he said.
"It just means we have to keep on keeping on".
So far, it has not been a remarkably bad year for flu deaths.
Another 10 children were reported to have died of the flu in the week ending February 3, bringing the total infant mortality so far this season to 63, Dr. Anne Schuchat, the CDC's acting director, told reporters. Flu and flu-related pneumonia deaths have lagged a little behind some recent bad seasons. They have gone as high as about 170 in a season.
The dominant flu strain this season, influenza A (H3N2), is especially potent, linked with severe disease and death, particularly among children and the elderly.
But reports of deaths - some in otherwise healthy children and young adults - have caused growing fear and concern, health officials acknowledge.
It was unclear whether the outbreak had reached its peak or if it would get worse, Schuchat said.
The CDC said the amount of suspected flu cases at doctor office and hospitals last week matched that seen in 2009, when a new swine flu epidemic swept the country and panicked many people. Swine flu, also called pandemic H1N1, was a new strain that hadn't been seen before.
This flu season, hospitalization rates have surpassed the nasty season of the winter of 2014-2015, when the vaccine was a poor match to the main bug.
Health officials have said this year's vaccine targets the flu viruses that are now making people sick, including the swine flu virus that has become a regular winter threat.
Doctors say they're a bit bewildered as to why this season is so intense. "It's not a hugely new strain. I don't think we know".