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).

There have been at least 24 million illnesses, 310,000 hospitalizations and 13,000 deaths from flu so far this season, according to the CDC. The agency said in its weekly flu surveillance report that seasonal influenza activity continues to increase across the country.

The United States is seeing a second peak in flu cases this season. After doctor’s office visits for flu dipped early this year, they jumped past the previous season peak at the end of last month, with a 30% test positivity rate — and there are still months to go.

So far this season, the CDC estimates, there have been 13,000 flu deaths — including at least 57 children. The flu has forced schools to shut down in some states.

The Centers for Disease Control and Prevention lists Illinois in the high category for flu cases, and across the Chicago area, emergency department visits, hospital admissions, and ICU admissions for the flu are currently higher than the peak of last season.