CHICAGO - Beginning Thursday, March 4 at 8:30 a.m., Illinois seniors can schedule their first COVID-19 vaccine appointment at the United Center vaccine site, which will begin to administer a limited number of vaccines on March 9, with a full opening March 10. Following this exclusive appointment period for seniors, all Illinoisans eligible under the state's Phase 1B+ will be able to schedule appointments on Sunday, March 7 at 4 p.m.