The map of flu activity across the United States continues to darken, both figuratively and literally, as case numbers spike upward in most states, according to the Centers for Disease Control and Prevention (CDC).

The U.S. influenza rate is at or near its highest level in at least 15 years and is still on the rise, the U.S. Centers for Disease Control and Prevention said on Friday. There have been at least 24 million illnesses,

Outpatient health care visits for flu-like illnesses are at their highest levels in 15 years, according to data updated Friday by the CDC.

Flu activity is at its highest level since 2009, forcing school closures and overwhelming hospitals across the U.S.

With a halt on scientific data being shared publicly, the CDC is getting crafty to warn of increasing flu hospitalizations.

One indicator of flu activity is the percentage of doctor’s office visits driven by flu-like symptoms. Last week, that number was clearly higher than the peak of any winter flu season since 2009-2010.