Flu levels have surged to their highest levels since the 2009 swine flu pandemic, with influenza-related emergency department visits remaining very high across the U.S. The flu continues to drive the most respiratory illness activity and officials warn that flu-related emergency department visits are expected to remain high in the coming weeks.

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.