A flu vaccine is readied at the L.A. Care and Blue Shield of California Promise Health Plans' Community Resource Center in Lynwood, Calif., on Friday, Oct. 28, 2022. On Friday, Nov. 17, 2023, the Centers for Disease Control and Prevention says the U.S. flu season is underway, with at least seven states reporting high levels of illnesses and cases rising in other parts of the country. (AP Photo/Mark J. Terrill, File)